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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
A comprehensive guide to a new technology for enabling high-performance spectroscopy and laser sources Resonance Enhancement in Laser-Produced Plasmas offers a guide to the most recent findings in the newly emerged field of resonance-enhanced high-order harmonic generation using the laser pulses propagating through the narrow and extended laser-produced plasma plumes. The author--a noted expert in the field--presents an introduction and the theory that underpin the roles of resonances in harmonic generation. The book also contains a review of the most advanced methods of plasma harmonics generation at the conditions of coincidence of some harmonics, autoionizing states, and some ionic transitions possessing strong oscillator strengths. Comprehensive in scope, this text clearly demonstrates the importance of resonance-enhanced nonlinear optical effects leading to formation of efficient sources of coherent extreme ultraviolet radiation that can be practically applied. This important resource: * Puts the focuses on novel applications of laser-plasma physics, such as the development of ultrashort-wavelength coherent light sources * Details both the theoretical and experimental aspects of higher-order harmonic generation in laser-produced plasmas * Contains information on early studies of resonance enhancement of harmonics in metal-ablated plasmas * Analyzes the drawbacks of different theories of resonant high order harmonic generation * Includes a discussion of the quasi-phase-matching and properties of semiconductor plasmas Written for researchers and students in the fields of physics, materials science, and electrical engineering who are interested in laser physics and optics, Resonance Enhancement in Laser-Produced Plasmas offers an introduction to the topic and covers recent experimental studies of various resonance processes in plasmas leading to enhancement of single harmonic.
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Seitenzahl: 693
Veröffentlichungsjahr: 2018
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Table of Contents
Cover
Dedication
Preface
References
Chapter 1: High‐Order Harmonic Studies of the Role of Resonances on the Temporal and Efficiency Characteristics of Converted Coherent Pulses: Different Approaches
1.1 Resonance Harmonic Generation in Gases: Theory and Experiment
1.2 Role of Resonances in Plasma Harmonic Experiments: Intensity and Temporal Characterization of Harmonics
References
Chapter 2: Different Theoretical Approaches in Plasma HHG Studies at Resonance Conditions
2.1 Comparative Analysis of the High‐Order Harmonic Generation in the Laser Ablation Plasmas Prepared on the Surfaces of Complex and Atomic Targets
2.2 Nonperturbative HHG in Indium Plasma: Theory of Resonant Recombination
2.3 Simulation of Resonant High‐Order Harmonic Generation in Three‐Dimensional Fullerenelike System by Means of Multiconfigurational Time‐Dependent Hartree–Fock Approach
2.4 Endohedral Fullerenes: A Way to Control Resonant HHG
References
Chapter 3: Comparison of Resonance Harmonics: Experiment and Theory
3.1 Experimental and Theoretical Studies of Two‐Color Pump Resonance‐Induced Enhancement of Odd and Even Harmonics from a Tin Plasma
3.2 Comparative Studies of Resonance Enhancement of Harmonic Radiation in Indium Plasma Using Multicycle and Few‐Cycle Pulses
3.3 Indium Plasma in the Single‐ and Two‐Color Near‐Infrared Fields: Enhancement of Tunable Harmonics
3.4 Resonance Enhancement of Harmonics in Laser‐Produced Zn II and Zn III Containing Plasmas Using Tunable Near‐Infrared Pulses
3.5 Application of Tunable NIR Radiation for Resonance Enhancement of Harmonics in Tin, Antimony, and Chromium Plasmas
3.6 Model of Resonant High Harmonic Generation in Multi‐Electron Systems
References
Chapter 4: Resonance Enhancement of Harmonics in Metal‐Ablated Plasmas: Early Studies
4.1 Indium Plasma: Ideal Source for Strong Single Enhanced Harmonic
4.2 Harmonic Generation from Different Metal Plasmas
4.3 Peculiarities of Resonant and Nonresonant Harmonics Generating in Laser‐Produced Plasmas
References
Chapter 5: Resonance Processes in Ablated Semiconductors
5.1 High‐Order Harmonic Generation During Propagation of Femtosecond Pulses Through the Laser‐Produced Plasmas of Semiconductors
5.2 27th Harmonic Enhancement by Controlling the Chirp of the Driving Laser Pulse During High‐Order Harmonic Generation in GaAs and Te Plasmas
5.3 Resonance Enhanced Twenty‐First Harmonic Generation in the Laser‐Ablation Antimony Plume at 37.67 nm
References
Chapter 6: Resonance Processes at Different Conditions of Harmonic Generation in Laser‐Produced Plasmas
6.1 Application of Picosecond Pulses for HHG
6.2 Size‐Related Resonance Processes Influencing Harmonic Generation in Plasmas
References
Chapter 7: Comparison of the Resonance‐, Nanoparticle‐, and Quasi‐Phase‐Matching‐Induced Processes Leading to the Growth of High‐Order Harmonic Yield
7.1 Introduction
7.2 Quasi‐Phase‐Matched High‐Order Harmonic Generation in Laser‐Produced Plasmas
7.3 Influence of a Few‐Atomic Silver Molecules on the High‐Order Harmonic Generation in the Laser‐Produced Plasmas
7.4 Controlling Single Harmonic Enhancement in Laser‐Produced Plasmas
7.5 Comparison of Micro‐ and Macroprocesses During the High‐Order Harmonic Generation in Laser‐Produced Plasma
References
Summary
Index
End User License Agreement
List of Tables
Chapter 3
Table 3.1 The autoionizing properties of some transitions of the tin ions.
Chapter 4
Table 4.1 Simulations of Mn and Au plasma characteristics at different heating pulse intensities using the HYADES code.
List of Illustrations
Chapter 1
Figure 1.1 Coupling scheme in argon atoms with relevant energy levels. The short designation (5p/5p′) indicates the manifold of closely spaced states 5p′ [3/2]
2
, 5p [1/2]
0
, 5p [3/2]
2
, and 5p [5/2]
2
. Full arrows depict the driving laser at 524 nm, dashed arrows indicate the 5th, 7th, and 9th harmonics, as investigated in the experiment.
Figure 1.2 The calculated harmonic spectrum in the vicinity of the resonance for different fundamental wavelengths, leading to different detunings from the resonance. The resonant transition is the 4d
10
5s
2
5p
2
P
3/2
↔ 4d
9
5s
2
5p
2
(
1
D)
2
D
5/2
transition in Sn
+
; the transition frequency is 26.27 eV, which is close to the 17th harmonic of a Ti:sapphire laser.
Figure 1.3 Harmonic spectra from chromium plasma including the resonance harmonic (H29).
Chapter 2
Figure 2.1 Harmonic intensities as functions of the harmonic order for the HHG from the Sb II (bottom panel), Cr II (middle panel), and Te II (top panel). The intensity of applied linearly polarized laser field is 4 × 10
14
W cm
−2
.
Figure 2.2 Harmonic intensities as functions of the harmonic order for the HHG by a linearly polarized laser field having the intensity 4 × 10
14
W cm
−2
. (a) Cr, Te, and double target Cr ± Te with constructive (+) and destructive (−) interferences of the resonant harmonic contributions. (b) Sb, Cr, and double target SbCr.
Figure 2.3 Intensity distribution of harmonics for singly charged indium ion and absorption spectrum of the singly charged indium ion.
Figure 2.4 Comparative plots of three possible harmonic generation models. 1 – Nonresonant HHG case (ordinary three‐step process); 2 – HHG from coherent superposition of states having different parity; 3 – HHG from resonant recombination.
Figure 2.5 The influence of resonance on the HHG spectrum generating in fullerene‐like medium in the cases of radiation of carrier wave frequencies 0.046 (open circles) and 0.057 au (filled squares). Inset: Absorption spectrum of the fullerene‐like system obtained by delta‐kick method.
Figure 2.6 The influence of approximations on the observation of resonant HHG. (a) Without the influence of exchange, (b) without the influence of interaction, (c) six expansion functions, (d) three expansion functions, and (e) one expansion function.
Figure 2.7 Results of simulation of the HHG for various deviations of carrier wave frequency from the resonant one for regimes favorable for coherent superposition or resonant recombination.
Figure 2.8 Absorption spectra of (a) original C
60
fullerene, (b) endohedral In@C
60
fullerene, and (c) endohedral Sb@C
60
fullerene. Energy is given in harmonics of fundamental radiation with frequency 0.057 au
Figure 2.9 HHG spectra from (a) original C
60
fullerene, (b) endohedral In@C
60
fullerene, and (c) endohedral Sb@C
60
fullerene. Intensities are normalized so that intensity of the 1st harmonic (i.e. fundamental intensity) is 10 000 (not shown).
Chapter 3
Figure 3.1 Experimental setup:
HPP
,
heating pump pulse
;
FPP
,
femtosecond probe pulse
; M, mirrors; VC,
vacuum chamber
; T, target;
FM
,
focusing mirror
;
FFG
,
flat field grating
;
MCP
,
microchannel plate
; and CCD, charge‐coupled device.
Figure 3.2 Harmonic spectra from the tin plasma in the case of (a) single‐color and (b) two‐color pump schemes.
Figure 3.3 Tuning of 15th and 17th harmonics by changing the distance between the gratings in the compressor stage. Positive and negative values of pulse duration correspond to positively and negatively chirped pulses.
Figure 3.4 The photoabsorption cross‐section spectra of Sn II 4d
10
5s
2
5p → 4d
9
5s
2
5p
2
(top), Sn III 4d
10
5s
2
→ 4d
9
5s
2
5p (middle), and Sn III excited state 4d
10
5s5p → 4d
9
5s5p
2
(bottom) convolved with a Gaussian instrumental function of width 30 meV. Dashed lines show 780 nm radiation harmonic frequencies.
Figure 3.5 (a) Harmonic spectrum calculated for Sn II. The laser intensity is 10
15
W cm
−2
. (b) The calculated resonant 17th harmonic enhancement as a function of the harmonic photon energy. The arrow shows the frequency of the transition in the absence of the laser field.
Figure 3.6 Harmonic spectra calculated for Sn II and Sn III* ions in the two‐color field (800 + 400 nm). The fundamental intensities are presented in the figures. In graphs (a) and (b) one can see the resonant enhancement of the 17th harmonic in Sn II and the 18th harmonic in Sn III*. The enhancement of the group of harmonics (graph (c)) can be attributed to the ionization broadening of the resonance.
Figure 3.7 Experimental arrangement of rotating target configuration.
Figure 3.8 (a) Raw image of the low‐order harmonic spectrum generated from an indium plasma in the case of 30 fs (FWHM) driving pulses. The thin line with high divergence above the 13th harmonic is a resonance transition at 19.92 eV. (b) Spectral distribution of indium harmonics, along the whole range of harmonic generation, using multicycle (30 fs) pulses. The highest order obtained is the 33rd harmonic.
Figure 3.9 Raw images and line‐outs of the spectra of the indium plasma emission upon excitation by 3.5 fs (FWHM) pulses using the heating pulse intensities of (a)
I
ps
= 5 × 10
9
W cm
−2
and (b)
I
ps
= 8 × 10
9
W cm
−2
. At low heating pulse intensity (a) one can see the highly divergent 19.92 eV resonance emission and its enhanced central part accompanied with some additional lines in (b). In the latter case the intensity of the 19.92 eV emission exceeds that of other emissions (at ∼21.9, 23.3, 24.1, and 25.2 eV), though not as strongly as in the case of emission of the harmonics shown in Figures 3.2b and 3.3a. (c) Raw image and line‐out of harmonic spectra from a carbon plasma obtained by excitation with 3.5 fs pulses. Broadband harmonics are observed in this case, which could be distinguished from the emission lines shown in (a) and (b). The 11th, 13th, and 15th harmonic energies are centered at ∼17.7, ∼20.9, and ∼24.15 eV, respectively.
Figure 3.10 Spectra of emission generated from the indium plasma using 3.5 fs pulses (a) without and (b) with double slits.
Figure 3.11 Variation of emission from the indium plasma excited by 3.5 fs pulses at different pressures of neon in hollow fiber. Upper panel shows the divergence of excited line at 3 bar of Ne.
Figure 3.12 Single particle response in the XUV range to the 3.9 fs laser pulse calculated via numerical TDSE solution for a model In II ion.
Figure 3.13 (a) Intensity of the XUV emission in the vicinity of the ion transition 4d
10
5s
2 1
S
0
→ 4d
9
5s
2
5p(
2
D)
1
P
1
from the ground state to an AIS as a function of time. (b) The CEP averaged energy of the resonant XUV emission (from 12
ω
to 14
ω
) as a function of the laser pulse duration
τ
FWHM
under constant laser pulse energy.
Figure 3.14 (a) Resonant XUV energy for the given laser intensity (empty circles) and averaged over the laser intensity up to 4 × 10
14
W cm
−2
(filled squares) as a function of CEP of the 3.9 fs pulse. (b) The resonant XUV energy as a function of the peak laser intensity for CEP
ϕ
= 0 (cos‐like pulse) and CEP
ϕ
= π/2 (sin‐like pulse).
Figure 3.15 Harmonic spectra generated from indium plasma in the case of a fixed CEP ((a)
ϕ
= 0 and (b)
ϕ
= π/2) of few‐cycle pulses and strong excitation of the indium target. Squares show frequencies and oscillator strengths (
gf
values) of the transitions in In II and In II* taken from Ref. [37] (only transitions with
gf
values exceeding 0.3 are shown). Arrows indicate the frequencies of the harmonics in carbon plasma shown in Figure 3.3c.
Figure 3.16 Conditions of phase matching between the waves of a broadband driving field and harmonics approaching the short‐wavelength side of the resonant transition of the plasma medium. Solid curve shows a dispersion of the refractive index of plasma. Dotted curve represents the spectral shape of a nearby broadband harmonic. The filled area near
λ
sh
shows a possible enhancement range of the part of harmonic spectrum where the phase mismatch became suppressed. Here
λ
r
denotes the wavelength of the ion resonance,
λ
d
,
λ
ch
, and
λ
sh
the wavelengths of the driving radiation, the center of the harmonic, and the short‐wavelength side of the harmonic respectively and
n
d
and
n
sh
the refractive indices of plasma at
λ
d
and
λ
sh
, respectively.
Figure 3.17 (a) Experimental setup. TiS, Ti:sapphire laser; TOPAS, optical parametric amplifier; PP, pump pulse for pumping the optical parametric amplifier; SP, amplified signal pulse from OPA; HP, heating picosecond pulse from Ti:sapphire laser;
SL
,
spherical lens
;
CL
,
cylindrical lens
; VC, vacuum chamber; T, target; EP, extended indium plasma;
NC
,
nonlinear crystal
(BBO); C, calcite; TP, thin glass plates;
HB
,
harmonic beam
; XUVS, extreme ultraviolet spectrometer. (b) Spectral tuning of mid‐infrared signal and idler pulses.
Figure 3.18 (a) Harmonic spectra using 1330 (upper panel) and 810 nm (bottom panel) pulses. Upper panel magnified with a factor of 7 for better comparison of the harmonic spectra generated using different pumps. (b) Spectra of tunable harmonics in the case of single‐color pump of indium plasma using idler (1728 − 2100 nm) pulses of OPA.
Figure 3.19 (a) Tuning of H21 along the In II resonance. Upper panel shows the indium plasma emission spectrum. Three bottom panels show resonantly enhanced harmonic using single‐color pump (1280, 1305, and 1340 nm, respectively). Dotted line shows the position of the resonance transition of In II. (b) Comparative harmonic spectra from indium plasma using single‐color (1290 nm; thick curve) and two‐color (1290 and 645 nm; thin curve) pumps. (c) Relative variations of H21 and H22 yields using different wavelengths of NIR and H2 pump radiation. Dotted lines show the tuning of H21 and H22. Dashed line shows the position of resonance transition.
Figure 3.20 (a) Harmonic spectra generated using the BBO crystal inserted inside (upper panel) and outside (middle panel) the vacuum chamber. Bottom panel shows generation of the odd harmonics of 655 nm radiation once the calcite plate was installed in front of BBO crystal, which led to variation of the polarization of NIR pulse from linear to circular. (b) Harmonic spectra for variable phase difference between NIR and H2 pulses. One can see a gradual change of the relative intensities of H13 and resonance‐enhanced H21 using different number of inserted 0.15 mm thick BK7 plates.
Figure 3.21 Simulated harmonic spectra from indium ion with single‐color (thin line) and two‐color (thick line) fields. The relative phase in the two‐color field is 0..
Figure 3.22 Simulated variations of high‐order harmonic yield using different wavelengths of NIR laser fields. Dashed lines show the tuning of the 21st and 22nd orders of harmonics..
Figure 3.23 Temporal profiles of resonant emission (from H20 to H22) in the case of single‐color (thick solid curve) and two‐color (thin solid curve) pumps. The relative phases in Figure 3.23a,b are 0 and 0.5π, respectively. The dashed line shows the electric field of 1300 nm pulse..
Figure 3.24 (a) Dependences of H19 and H21 yields on the relative phase between the 1300 nm and its second harmonic pulses. (b) Variation of the relative intensities of the 21st and 19th harmonic with relative phase. (c) Simulated harmonic spectra with different relative phases of 0 and 0.5π..
Figure 3.25 (a) Harmonic spectra from zinc plasma using 806 nm (thin curve) and 1320 nm (thick curve) pulses measured at similar conditions. (b) Comparative spectra from Zn plasma in the case of single‐color (thick curve) and two‐color (thin curve) pumps at similar conditions of experiment.
Figure 3.26 Tunable harmonic spectra in the cases of (a) weak, (b) moderate, and (c) strong excitation of Zn target (see text for further details). Dashed lines show the tuning of harmonics. Solid lines show the ionic transitions responsible for enhancement of harmonics.
Figure 3.27 Enhancement of the part of H20 at the conditions of coincidence of this harmonic with the 67.8 nm transition of Zn III.
Figure 3.28 Spectral regions of lines corresponding to the transitions to excited states (in particular, to AIS) in Zn I, Zn II, Zn III according to the published data (from top to bottom [68, 69, 72, 73], and [70] correspondingly).
Figure 3.29 The harmonic spectra calculated via TDSE numerical solution in the linear (a) and logarithmic (b) scales. The fundamental wavelengths are presented in the graphs. The dashed lines show the tuning of harmonics, the solid line shows the ionic transition.
Figure 3.30 (a) Harmonic spectra using 806 nm driving pulses in Sn, Sb, and Cr plasmas showing the resonance enhancement of the single harmonics (H17, H21, and H29, respectively). (b) Raw images of the tunable harmonic spectra using the pump of chromium plasma by NIR + H2 pulses. NIR pulses were tuned in the range of 1280–1460 nm. Dashed lines in this and other figures show the tuning of specific harmonics. One can see the notable enhancement of harmonics in the vicinity of 27 nm and significant decrease of harmonic yield in the range of 29.5–31 nm. (c) Comparative spectra of the harmonics generated in Cr plasma using the 1300 + 650 nm and 806 nm pumps. The NIR‐induced curve was shifted along the
y
‐axis for better visibility and comparison with the 806 nm induced harmonic spectrum.
Figure 3.31 (a) Tuning of resonance‐enhanced harmonics generated in the 47 nm region using the two‐color pulses propagated through the tin plasma. (b) Harmonic spectra from Sb plasma at different NIR + H2 pumps. (c) Tuning of harmonics in the region of strong ionic transition of antimony (37.5 nm).
Figure 3.32 (a) Harmonic intensities as functions of the harmonic order for HHG from Sn II. The laser field intensity is 2 × 10
14
W cm
−2
and
φ
= 0
for single‐color field, and
I
1
= 1.5 × 10
14
W cm
−2
and
I
2
= 0.5 × 10
14
W cm
−2
with
r
= 1,
s
= 2,
φ
r
=
φ
s
= 0
for two‐color field. The fundamental wavelengths are indicated in the upper right corner of both panels as well as corresponding resonant harmonics. Numerical results for single‐color laser field are presented by solid line with filled circles while the numerical results for two‐color laser field are presented by solid line with filled squares. (b) Same as in (a), but for Sb II. The resonant harmonic for 806 nm is H21, while the resonant harmonic for single‐color (two‐color) field with 1350 nm is H35 (H36). (c) Same as in (a), but for Cr II. The resonant harmonic for 806 nm is H29, while the resonant harmonic for single‐color (two‐color) field with 1280 nm is H47 (H46).
Figure 3.33 Harmonic intensities as functions of the harmonic order for HHG from Sn II by two‐color field whose components have the same intensities and wavelengths as in the lower panel of Figure 3.32a, for
φ
s
= 0
and for three different phases
φ
r
= 0, π/6, and π/3
as denoted. The inset in the upper right corner shows the corresponding electric field vectors.
Figure 3.34 Harmonic intensities as functions of the harmonic order for HHG from Sb II for different fundamental wavelengths starting from 1290 nm (bottom panel) to 1410 nm (top panel). The other laser parameters are as in the lower panel of Figure 3.32b.
Figure 3.35 Level splitting in two‐channel approximation in the presence of resonance near channel‐closing.
Figure 3.36 Absorption spectrum of singly charged indium ion (dashed line, shifted by 2 units of relative intensity for better visibility) and resonant HHG spectrum (solid line) of the full system.
Figure 3.37 Time dependence of the electron return energy (black filled area) and the excited state population (upper line) for 35 fs pulses with Gaussian envelope; peak intensity: 5 × 10
14
W cm
−2
. The maximum excited state population reached 17.5% (upper line, which shifted upward by 30 units for better visibility).
Figure 3.38 Plasma and harmonic emission spectra generating in the indium plasma. Upper panel: plasma emission at overexcitation of ablating target. Second panel: single‐color pump (806 nm) of optimally formed indium LPP. Third panel: two‐color pump (1431 + 715.5 nm) of optimally formed indium LPP. Fourth panel: two‐color pump (1521 + 760.5 nm) of optimally formed indium LPP. Two bottom panels were magnified with the factor of 6× compared with the second panel due to notably smaller conversion efficiency in the case of longer wavelength pumps. Solid line corresponds to the In II transition responsible for the enhancement of harmonics. Dotted lines show the emission lines of In plasma observed in all these cases.
Chapter 4
Figure 4.1 High‐order harmonic spectra from (1) indium and (2) silver plumes.
Figure 4.2 The 13th harmonic intensity as a function of the angle of rotation of quarter‐wavelength plate.
Figure 4.3 Harmonic spectra from indium plasma using (a) 796, (b) 782, and (c) 775 nm main pulse. (d) Spectrum of In plasma generated at high intensity of heating pulse radiation.
Figure 4.4 Schematic of the experimental setup on high‐order harmonic generation from indium‐containing plasmas. VC, vacuum chamber; T, target; S, slit; G, grating; L, lenses; MCP, microchannel plate; CCD, charge‐coupled device; FP, femtosecond pulse; PP, picosecond heating pulse.
Figure 4.5 Spectral measurements of the In, InSb, InGaP, and InP plasmas produced at the tight and weak focusing conditions of the heating pulse radiation.
Figure 4.6 SEM images of indium film deposited on the silicon wafer at (a) weak and (b) tight focusing of the heating pulse radiation.
Figure 4.7 Harmonic distribution images in the case of indium plasma at the conditions of (a) chirp‐free 48 fs pulses, (b) negatively chirped 95 fs pulses, and (c) negatively chirped 250 fs pulses.
Figure 4.8 The 13th harmonic intensity from indium plume as a function of the time delay between the heating and the driving pulses.
Figure 4.9 Dependence of the 19th harmonic yield on the driving pulse energy in the case of indium plasma. Inset: Variation of the 21st harmonic intensity as a function of the distance between the target surface and the axis of the driving radiation.
Figure 4.10 Variation of the harmonic spectrum from indium plume with the pulse chirp and pulse width. (a) chirp‐free 48 fs pulses, (b) negatively chirped 95 fs pulses, and (c) negatively chirped 250 fs pulses. Each curve is shifted vertically to avoid overlap for visual clarity.
Figure 4.11 Harmonic spectra from InP, In, InGaP, and InSb plumes.
Figure 4.12 Variation of the 21st harmonic yield with chirp of the driving pulse: (a) positively chirped 80 fs pulses, (b) chirp‐free 48 fs pulses, (c) negatively chirped 90 fs pulses, (d) negatively chirped 160 fs pulses. Each curve is shifted vertically to avoid overlap for visual clarity.
Figure 4.13 (a) The 19th harmonic intensity as a function of the delay between heating and main pulses, and (b) emission spectrum of chromium plasma in the visible range at optimal conditions of frequency conversion.
I
hp
= 4 × 10
10
W cm
−2
.
Figure 4.14 Harmonic (a) and emission (b) spectra from chromium plasma in XUV range. (c) High‐order harmonic intensity distribution in the plateau region.
Figure 4.15 Comparison of harmonic spectra from (a) chromium and (b) boron plumes.
Figure 4.16 Harmonic spectra from manganese plasma in the case of 400 nm driving radiation.
Figure 4.17 Harmonic spectra from Cr plasma in the case of 800 nm, 35 fs chirp‐free main pulses.
Figure 4.18 Variation of 29th harmonic intensity at different chirps of 800 nm radiation. Chromium plasma.
Figure 4.19 Harmonic spectrum from Cr plasma in the case of 400 nm driving pulses.
Figure 4.20 Variations of 21st harmonic yield from Sb plasma at different chirps of driving 800 nm radiation.
Figure 4.21 Harmonic distribution in the case of Sn plume.
λ
= 800 nm.
Figure 4.22 Tuning of 17th harmonic at different chirps of driving radiation. Tin plasma.
Figure 4.23 Harmonic spectra from Ag plasma in the cases of (a) apertureless and (b) apertured single color pump (780 nm). (c) Tuning of 17th and 19th harmonics by changing the distance between the gratings in the compressor stage. Positive and negative values of pulse duration correspond to positively and negatively chirped pulses. Dotted lines show the tuning of 17th and 19th harmonics with different chirps. Black lines show the wavelengths of these harmonics at chirp‐free conditions. Thick black lines on the left side of bottom graph show the tuning range of 17th harmonic (2.8 nm).
Figure 4.24 (a) Harmonic spectra from Ag plasma using the two‐color pump configuration. (b) Optimization of even harmonics with regard to the odd ones in the cutoff region. (c) Harmonic spectra using 200 mm focal length focusing mirror. (d) Harmonics spectra using the 500 mm focal length lens.
Figure 4.25 (a) Harmonic spectra from chromium plasma at different chirps of laser radiation. Positive and negative values of pulse duration correspond to positively and negatively chirped pulses. (b) Harmonic spectrum at overexcited conditions of Cr plasma formation, with ionic lines appearing close to the enhanced 27th and 29th harmonics. The arrow shows one of these lines close to the 27th harmonic.
Figure 4.26 (a) Two‐color pump‐induced spectra of harmonics from Cr plasma and (b) the spectra obtained at analogous experimental conditions by removing the second harmonic crystal from the path of 780 nm radiation.
Figure 4.27 Variations of harmonic spectra at (a) weak excitation of V target (
I
ps
= 6 × 10
9
W cm
−2
), (b) stronger excitation of target (
I
ps
= 1 × 10
10
W cm
−2
), and (c) application of two‐color pump.
Figure 4.28 Experimental setup for measuring the spatial coherence of high harmonics generated in ablation plasma plumes and gas targets. A chirped pulse amplification system with a hollow fiber pulse compressor was used to produce the few‐cycle pulses to drive HHG. A beam‐splitter (BS) was used to pick off part of the stretched laser pulse for ablation. A rotating target set‐up allows operation at 1 kHz pulse repetition rate. The harmonics were analyzed using a spatially resolving XUV spectrometer with microchannel plate (MCP) detector. Double slits could be introduced into the harmonic beam to produce an interference pattern on the detector, from which the coherence of the radiation could be determined.
Figure 4.29 Nonresonant high harmonics generated in a carbon plasma plume. (a) Spatially resolved HHG spectrum showing interference fringes from the double slits. (b) Spectral line out. (c) Spatial line out of the interference pattern for the 13th harmonic. The average visibility of fringes near the center of the pattern is
V
= 0.63.
Figure 4.30 Resonantly enhanced high harmonics generated in a zinc plasma plume. (a) Spatially resolved HHG spectrum showing interference fringes from the double slits. (b) Spectral line out showing enhancement of the 11th harmonic due to its overlap with a plasma transition line in Zn
+
at 18.3 eV marked by solid line in (a). (c) Spatial line out of the resonant harmonic. The average visibility of fringes near the center of the pattern is
V
= 0.74.
Figure 4.31 Resonantly enhanced high harmonics generated in an indium plasma plume. (a) Spatially resolved HHG spectrum showing interference fringes from the double slits. (b) Spectral line out showing enhancement of the 13th harmonic due to its overlap with a plasma transition line in In
+
at 19.9 eV marked by solid line in (a). (c) Spatial line out of the resonant harmonic. The average visibility of fringes near the center of the pattern is
V
= 0.66.
Figure 4.32Figure 4.32 High harmonics generated in argon gas. (a) Spatially resolved HHG spectrum showing interference fringes from the double slits. (b) Spectral line out. (c) Spatial line of the 15th harmonic. The average visibility of fringes near the center of the pattern is
V
= 0.44.
Figure 4.33 Maximum harmonic order observed as a function of the ionization potential of singly charged and doubly charged ions from various targets. The averaged line shows an empirical relation
H
(harmonic cutoff) ≈ 4
I
i
eV − 32. Filled squares are the results obtained in discussed work, open circles are the results obtained from Refs. [70, 86], and open triangles are the results of Ref. [90].
Figure 4.34 Harmonic spectrum from manganese ablation obtained at
I
fp
= 5 × 10
14
W cm
−2
and
I
pp
= 1 × 10
10
W cm
−2
.
Figure 4.35 A lineout of high‐order harmonic spectrum obtained at
I
fp
= 3×10
15
W cm
−2
and
I
pp
= 3 × 10
10
W cm
−2
. Inset: A region of resolved harmonic distribution from the 67th to 101st orders.
Figure 4.36 Harmonic cutoff as a function of main pulse intensity.
Figure 4.37 Time‐resolved UV spectra of the “optimal” plasma produced on the surface of manganese target.
I
pp
≈ 3×10
10
W cm
−2
.
Figure 4.38 Harmonic spectra from the silver plasma (a) and manganese plasma (b).
Figure 4.39 Raw images of harmonic spectra from manganese plasma in the case of (a) 40 fs and (b) 3.5 fs probe pulses obtained at the same intensity. (c) Raw images of harmonic spectra from Mn plasma at different pressures of neon in the hollow fiber obtained at the same energy of probe laser pulses.
Figure 4.40 (a) Potential used for the numerical simulations. Calculated HHG spectra using (b) a long (40 fs) pulse and (c) few‐cycle pulses at different values of the CEP (
ϕ
= 0, π/4, and π/2).
Figure 4.41 Experimental harmonic spectra generated from manganese plasma in the case of the absence of gas in the hollow fiber compressor (
t
= 25 fs) and random CEP (a), and at 3 bar pressure (
t
= 3.5 fs) at fixed CEP (
ϕ
= 0 (b);
ϕ
= π/2 (c)).
Figure 4.42 Calculated results for HHG driven by (a) a long (40 fs) pulse with CEP
ϕ
= π/4 and few‐cycle pulses with CEPs of (b)
ϕ
= 0, (c)
ϕ
= π/4, and (d)
ϕ
= π/2. The top panels show the HHG temporal intensity profile obtained as the square of the time‐dependent dipole acceleration after high‐pass filtering above 32.7 eV. The middle panels show the time‐frequency diagrams. The solid curves in the bottom panels show the time dependence of the electric field of the driving laser pulse.
Chapter 5
Figure 5.1 Experimental scheme for harmonic generation in the extended plasma plumes.
FDP
,
femtosecond driving pulse
;
PHP
,
picosecond heating pulse
; SL, spherical lens; CL, cylindrical lens; VC, vacuum chamber; W, windows of vacuum chamber; C, BBO crystal; T, target; EPP, extended plasma plume; S, slit; XUVS, extreme ultraviolet spectrometer; CM, cylindrical mirror; FFG, flat field grating; MCP, microchannel plate registrar; CCD, charge‐coupled device camera.
Figure 5.2 Harmonic spectra obtained from the (a) Ge, (b) Te, and (c) Sb plasmas. These plasmas were produced using the 4 mJ, 370 ps pulses. The intensity of driving pulses was 8 × 10
14
W cm
−2
.
Figure 5.3 Harmonic spectrum obtained from the Se plasma. This plasma was produced using the 4 mJ, 370 ps pulses. The intensity of driving pulses was 8 × 10
14
W cm
−2
.
Figure 5.4 Two‐color‐pump‐induced odd and even harmonic spectra obtained from the Te plasma. This plasma was produced using the 4 mJ, 370 ps pulses. The intensity of driving pulses was 8 × 10
14
W cm
−2
. The ratio of 401 and 802 nm pulse energies was 5 : 95. The polarizations of two pump waves were orthogonal to each other.
Figure 5.5 Harmonic spectra obtained from the ablation of As using different shapes of plasma formation. Thick curve: extended 5 mm long plasma. Thin curve: eight 0.3 mm long plasma jets. The plasma was produced using the 4 mJ, 370 ps pulses. The intensity of driving pulses was 8 × 10
14
W cm
−2
.
Figure 5.6 Schematic of the experimental setup on high‐order harmonic generation from GaAs plasma. VC, vacuum chamber; T, target; S, slit; G, grating; L, lenses; MCP, microchannel plate; CCD, charge‐coupled device; FP, femtosecond pulse; PP, picosecond pulse.
Figure 5.7 Spectral measurements of the GaAs plasma produced at the tight and weak focusing conditions of heating pulse radiation.
Figure 5.8 Dependence of 21st harmonic intensity on the focal position of driving laser radiation.
Figure 5.9 Harmonic spectra from GaAs plume as a function of pulse chirp and width. Each curve is shifted vertically to avoid overlap for visual clarity.
Figure 5.10 Comparison between (a) plasma spectrum and (b) harmonic spectrum of GaAs. It is seen from (c) that the harmonics fully disappear when the femtosecond beam is made circularly polarized. Each curve is shifted vertically to avoid overlap for visual clarity.
Figure 5.11 (a) Plasma spectrum of ablated arsenic plume, (b) harmonic spectrum from As plasma, and (c) harmonic spectrum from GaP plasma. Each curve is shifted vertically to avoid overlap for visual clarity.
Figure 5.12 HHG spectra from the tellurium and silver laser‐ablation plumes were obtained at the wavelength of (a) 13–35 and (b) 13–20 nm. A strong 27th harmonic at the wavelength of 29.44 nm was obtained. The spectra (a) and (b) were accumulated using 10 and 100 shots, respectively. Highest harmonic order obtained in these studies from the Te plume was the 51st one (
λ
= 15.59 nm).
Figure 5.13 HHG spectra from tellurium laser‐ablation plume for pump laser with central wavelength of 795 and 788 nm. The black and gray curves are the pumping laser wavelength of 795 and 788 nm, respectively. The enhancement of 27th harmonic radiation decreased compared to the neighboring harmonics as the central wavelength of laser radiation became shorter.
Figure 5.14 The enhancement factor of the harmonic as a function of the wavelength difference between the harmonic and the strong oscillator strength transition. The black solid circles is tellurium, the gray solid squares is tin, and the black triangles and squares are antimony and indium, respectively.
Figure 5.15 HHG spectra from the laser‐ablation antimony and silver plumes irradiated by femtosecond laser pulse. The black and gray lines are the harmonics from the antimony and silver plumes, respectively. The spectrum of the HHG from antimony at the wavelength range of 10–30 nm was accumulated using 100 shots. The HHG from the silver plume was accumulated using 10 shots. The curves are shifted vertically to avoid overlap for visual clarity.
Figure 5.16 HHG spectrum at the wavelength range of 33–65 nm from the laser‐ablation antimony plume. This spectrum was accumulated during 10 shots. The intensity of 21st harmonic was measured to be 20 times higher than those of the 23rd and 19th harmonics.
Figure 5.17 Intensities of the 21st (solid circles), 23rd (open squares), and 19th (open triangles) harmonics as the functions of the pump laser wavelength.
Chapter 6
Figure 6.1 Experimental setup for the HHG in laser plasma using the picoseconds pulses.
FP
,
fundamental probe
picosecond pulse;
PP
, heating picosecond pulse; M, mirror;
FL
,
focusing lenses
;
VC
,
vacuum chamber
; T, target;
VMR‐2
,
vacuum monochromator
; G, grating;
SS
,
sodium salicylate
; PMT, photomultiplier tube.
Figure 6.2 Plasma emission spectra from the (a) graphite, (b) pencil lead, and (c) glassy carbon at weak (solid lines,
I
= 7 × 10
10
W cm
−2
) and strong (dotted lines,
I
= 1.5 × 10
11
W cm
−2
) excitation of target surfaces.
Figure 6.3 Harmonic spectra from the (a) graphite, (b) pencil lead, (c) glassy carbon, and (d) manganese plasmas.
Figure 6.4 Distributions of the 5th, 7th, and 9th harmonic intensities in the cases of different carbon‐containing plasmas. (a) graphite, (b) glassy carbon, (c) pyrographite, (d) pencil lead, (e) silicon carbide, and (f) boron carbide.
Figure 6.5 (a) Polarization dependence of 5th (circles) and 7th (squares) harmonic intensities and different angles of rotation of the half‐wave plate. (b) The dependence of 7th harmonic intensity on the delay between the heating and probe pulses. Inset: Harmonic intensity as a function of the distance between the target surface and probe beam axis for the 7th harmonic.
Figure 6.6 Dependences of harmonic intensity on the heating pulse energy for the 7th (upper curve), 9th (middle curve), and 11th (bottom curve) harmonics generating in pyrographite plasma.
Figure 6.7 Harmonic spectra from the Sn, Pb, and Sn:Pb (5 : 3) alloy plasmas.
Figure 6.8 (a) The dependence of the 11th harmonic intensity on the delay between the pump and probe pulses. (b) Harmonic intensity as a function of the distance between Pb target surface and probe beam axis for the 7th (squares) and 11th (circles) harmonics.
Figure 6.9 (a) The dependence of the harmonic intensity on the pump pulse energy for the 11th harmonic generating in a lead plasma. (b) Comparison of experimental (squares, dashed curve) and calculated (solid curve) dependences of the 11th harmonic yield on the probe pulse intensity.
Figure 6.10 Variations of plasma harmonic spectra at different pressures of gases. (a) Pb plasma, He gas, (b) Pb plasma, Xe gas, and (c) carbon plasma, Xe gas.
Figure 6.11 Experimental setup for plasma harmonic generation.
DP
,
driving pulse
;
HP
,
heating pulse
;
SL
,
spherical lens
;
CL
,
cylindrical lens
; VC, vacuum chamber; T, target;
EP
,
extended plasma
;
NC
,
nonlinear crystal
(BBO);
HB
,
harmonic beam
;
XUVS
,
extreme ultraviolet spectrometer
.
Figure 6.12 TEM images of the (1) In
2
O
3
, (2) Mn
2
O
3
, and (3) Sn nanoparticles (a) before their ablation and (b) after deposition during ablation. White lines on the top panels correspond to 100 nm. Black lines on the bottom panels correspond to 200 nm.
Figure 6.13 Harmonic spectra in the cases of (a) ablation of bulk indium (see text), (b) ablation of indium oxide nanoparticles using the fluencies 0.7 J cm
−2
(thin curve) and 1.3 J cm
−2
(thick curve) on the target surface, (c) application of two‐color pump of the indium oxide nanoparticle‐containing plasma (13th harmonic was collected at saturation level to demonstrate the odd and even harmonic distribution), and (d) shortest wavelength harmonics generated during single‐ and two‐color pumps of the plasma produced on the indium bulk target. The harmonic orders are shown on the graphs.
Figure 6.14 Panel 1: lower order harmonic spectrum obtained from the plasma produced on the bulk manganese target (
F
= 0.8 J cm
−2
). Panel 2: harmonic spectrum obtained from the plasma produced on the target contained Mn
2
O
3
nanoparticles at optimal conditions of ablation (
F
= 0.8 J cm
−2
). Panel 3: plasma spectrum obtained at overexcitation of the Mn
2
O
3
nanoparticle‐containing target (
F
= 1.3 J cm
−2
). Panel 4: harmonic spectrum obtained using the two‐color pump of the plasma produced on the target contained Mn
2
O
3
nanoparticles (
F
= 0.7 J cm
−2
).
Figure 6.15 Harmonic spectra from the plasmas produced (a) on the Sn bulk target (
F
= 0.8 J cm
−2
) and (b) on the target contained Sn nanoparticles (
F
= 0.6 J cm
−2
). (c) Emission spectrum of emission from the pure glue ablation. No harmonics were observed in this plasma at various conditions of ablation.
Figure 6.16 Harmonic spectra obtained in the plasma plumes produced from (bottom panel) bulk carbon target, (middle panel) C
60
powder‐rich epoxy, and (upper panel) C
60
film. The dashed curve in the top panel corresponds to the photoionization cross‐sections near plasmon resonance. Inset shows the experimental set‐up of HHG in fullerenes.
MP
:
main pulse
; PP: picosecond pulse;
DL
:
delay line
; C: grating compressor; FL: focusing lenses; T: target; XUVS: extreme ultraviolet spectrometer; G: gold‐coated grating; MCP: micro‐channel plate; CCD: charge‐coupled device.
Figure 6.17 Variation of harmonic spectra observed at the consecutive shots on the same spot of fullerene film.
Chapter 7
Figure 7.1 (a) Experimental scheme for the harmonic generation in the multijet plasmas.
FDP
,
femtosecond driving pulse
;
PHP
,
picosecond heating pulse
;
SL
,
spherical lens
;
CL
,
cylindrical lens
; MSM, multislit mask;
VC
,
vacuum chamber
; T, target;
MJP
,
multijet plasma
; S, slit; XUVS, extreme ultraviolet spectrometer;
CM
,
cylindrical mirror
;
FFG
,
flat field grating
;
MCP
,
microchannel plate
detector; CCD, charge‐coupled device camera. (b) Images of the extended imperforated (upper panel) and eight‐jet (bottom panel) plasma formations produced on the surface of the silver target. The number of jets was increased and the sizes of jets were decreased by tilting the MSM.
Figure 7.2 Harmonic spectra generated in different multijet silver plasmas produced by tilting the MSM. Upper panel shows the harmonic spectrum generated in the 5 mm Ag plasma.
Figure 7.3 Variation of the spectral and spatial shapes of the harmonics generated in the extended and multijet silver plasmas using the (a) 1.85 mJ and (b) 5 mJ driving pulses. Insets in (a) and (b) show the far‐field images of the 37th harmonic in the cases of (1) multijet and (2) extended imperforated plasmas. One can see the equal divergences of the harmonics generated in the extended and perforated plasmas in the case of the 1.85 mJ driving pulse, while in the case of the 5 mJ pulse, the harmonic beam from the extended plasma became more divergent and strongly modulated compared with the one generated from the eight‐jet plasma.
Figure 7.4 Variations of maximally enhanced harmonic order at different energies of heating (filled squares) and driving (empty circles) pulses. One can see that the threefold growth of driving pulse energy (from 1.85 to 5 mJ) did not significantly change the
q
qpm
. In the meantime, the
q
qpm
was strongly dependent on the variation of the heating pulse energy. Solid and dotted lines are inserted for better viewing of the influence of heating and driving pulse energies on the QPM conditions.
Figure 7.5 Time evolution of pulse envelope and fractional populations for a medium initially composed of Ag
+
ions. In this case harmonics are produced mainly by Ag
+
in the leading part of the driving pulse.
Figure 7.6 Spatial (
r
,
z
) maps of harmonic orders H25 (plateau) and H45 (cutoff). Parameters:
I
dp
= 5 × 10
14
W cm
−2
,
p
= 1 Torr (3.3 × 10
16
cm
−3
), Ag
+
. (a) No ablated electrons are present and (b) all ablated electrons are included.
Figure 7.7 Spatial (
r
,
z
) maps of harmonic orders H25 (plateau) and H45 (cutoff). Parameters:
I
dp
= 5 × 10
14
W cm
−2
,
p
= 2 Torr (6.6 × 10
16
cm
−3
), Ag
+
. (a) No ablated electrons are present and (b) all ablated electrons are included.
Figure 7.8 Spatial (
r
,
z
) maps of harmonic H35. Parameters:
I
dp
= 3 × 10
14
W cm
−2
(two upper panels) and 5 × 10
14
W cm
−2
(two bottom panels),
p
= 2 Torr (6.6 × 10
16
cm
−3
), Ag
+
. (a) No ablated electrons are present and (b) all ablated electrons are included.
Figure 7.9 Experimental setup for nanopowder and bulk targets ablation for efficient harmonic generation.
HP
,
heating pulse
;
DP
,
driving pulse
; H2, second harmonic pulse; XUV; T, target; LPP.
Figure 7.10 (a) Raw images of harmonic spectra using two‐color pump (806 + 403 nm) and plasma emission from ablated Ag bulk target at optimal (upper panel) and overexcited (middle panel) ablation. Bottom panel shows the plasma emission without propagation of the driving pulses through the plasma. (b) Raw images of the low‐order harmonic spectra from ablated bulk Ag (upper panel) and Ag NPs at optimal ablation (second panel, 0.5 J cm
−
2
), stronger ablation (third panel, 0.8 J cm
−
2
), and overexcitation (bottom panel, 1.2 J cm
−
2
, no harmonic emission) of NP target.
Figure 7.11 (a) Harmonic spectra at optimal ablation of bulk Ag using single‐color pump (1310 nm, thick curve) and two‐color pump (1310 + 655 nm, thin curve) of extended plasma. (b) Raw images of harmonic spectra in the case of the three‐color pump of bulk Ag plasma (upper panel) and Ag NP plasma (bottom panel, see text).
Figure 7.12 TEM images of deposited material during ablation of (a) bulk silver and (b) silver NPs at different fluencies of heating pulses (0.4 and 0.7 J cm
−
2
in the case of top and bottom panels, respectively). The lengths of black markers correspond to (a, top) 20 nm, (b, top) 100 nm, (a, bottom) 20 nm, and (b, bottom) 200 nm.
Figure 7.13 Mass spectra of ablated (a) bulk silver and (b) silver NPs at different fluencies of heating pulses (see text).
Figure 7.14 Plasma and nonresonant harmonic spectra. (a) Raw images of plasma (upper panels) and harmonic (bottom panels) spectra obtained during ablation of Ag and Au targets and 810 nm femtosecond pulse propagation. Harmonic orders and wavelengths in this and most of the other figures are shown on the upper and bottom axes, respectively. (b) Raw images of harmonic (upper panel) and plasma (bottom panel) spectra obtained during ablation of Mg target and 1340 nm femtosecond pulse propagation. (c) Raw images of plasma (upper panel), plasma + harmonic (middle panel), and harmonic (bottom panel) spectra obtained during ablation of graphite target and 1340 + 670 nm femtosecond pulse propagation.
Figure 7.15 Samples of resonance‐induced enhancement of single harmonics in various plasmas. Upper, middle, and bottom panels correspond to the harmonic spectra generated in selenium, chromium, and tin plasmas using 810 nm, 1300 + 650 nm, and 1420 + 710 nm pumps, respectively. One can see the enhanced H35 in the case of selenium plasma and 806 nm pump. In the case of chromium plasma, harmonics surrounded H47 were notably stronger compared with those in the range of H41–H45 in the case of 1300 + 650 nm pump. Similarly, tin plasma allowed observation of the enhanced harmonics in the vicinity of H29 of 1420 + 710 nm pump.
Figure 7.16 (a) Raw images of plasma (upper panel) and harmonic (three other panels) spectra obtained during ablation of zinc. Harmonic spectra were tuned by changing the wavelength of driving NIR radiation and its second harmonic from 1320 + 660 nm (second panel from the top) to 1360 + 680 nm (third panel) and 1380 + 690 nm (fourth panel). Dashed lines show the positions of strong plasma emission lines in all four spectra. Dotted lines show the tuning of H14 and H20 at different pumps of plasma. The intensity of H20 remained approximately the same during tuning through the strong resonance transition (∼67.8 nm), while H17 was stronger in the case of 1320 + 660 nm pump. (b) Raw images of plasma (upper panel) and harmonic (five other panels) spectra obtained during ablation of antimony. Harmonic spectra were tuned by changing the wavelength of driving NIR radiation and its second harmonic from 1310 + 665 nm (second panel from the top) to 1390 + 695 nm (sixth panel) with a step of 20 nm. Solid lines show the tuning of H36 and H19 at different pumps of plasma. The harmonic orders shown on the top of images correspond to those generated using the 1310 + 655 nm pump. Most of the harmonics remain the same during variation of pump wavelength, excluding those in the region of 37.5 nm.
Figure 7.17 (a) Raw images of plasma (upper panel) and harmonic (two bottom panels) spectra obtained during ablation of cadmium. Harmonic spectra were tuned by changing the wavelength of driving NIR radiation from 1320 nm (third panel from the top) to 1360 nm (second panel). The harmonic orders shown on the top of images correspond to those generated using the 1360 nm pump. (b) Raw images of harmonic (two upper panels) and plasma (bottom panel) spectra obtained during ablation of indium. One can see the strong H13 in the case of 810 nm pump (upper panel). The harmonics from 1300 + 650 nm pump were also maximally enhanced in the same spectral region (61.5 nm, middle panel). The harmonic orders shown on the top of upper and middle images correspond to those generated using the 810 nm and 1300 + 650 nm pumps, respectively.
Figure 7.18 Raw images of plasma (upper panel) and harmonic (bottom panel) spectra obtained during ablation of manganese. The intensity of H33 of the 810 nm pump was notably stronger than lower order harmonics.
Figure 7.19 (a) Application of imperforated (thick curve) and multijet (thin curve) indium plasmas in the case of two‐color (1300 + 650 nm) pump. Inset shows two raw images of harmonic spectra obtained in the cases of the two‐color pump of expended imperforated indium plasma (upper panel) and silver plasma (bottom panel). (b) Comparative spectra from In multijet plasma in the case of single‐color (1310 nm, thick curve) and two‐color (1310 + 655 nm, thin curve) pumps.
Figure 7.20 Dependences of the QPM‐enhanced harmonics generated in the multijet indium plasma on the tuning of the driving NIR pulses. Upper panel shows the harmonic spectrum from imperforated indium plasma. Each panel contains the wavelengths of pumps and the pulse energies.
Figure 7.21 (a) Harmonic spectra generated from the low‐ionized chromium plasma using two‐color pump. Upper panel was obtained in the case of imperforated 5 mm long plasma, while bottom panel was obtained in the case of eight‐jet plasma. No QPM effect was observed in that case due to small density of free electrons appeared during laser ablation and tunnel ionization. (b) Harmonic spectra generated in the imperforated (thick curve) and multijet (thin curve) tin plasmas.
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Resonance Enhancement in Laser-Produced Plasmas
Concepts and Applications
Rashid A. Ganeev
Changchun Institute of Optics, Fine Mechanics and Physics, Changchun, China
Copyright
This edition first published 2018
© 2018 John Wiley & Sons Inc.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
The right of Rashid A. Ganeev to be identified as the author of this work has been asserted in accordance with law.
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Library of Congress Cataloging-in-Publication Data
Names: Ganeev, Rashid A., author.
Title: Resonance enhancement in laser-produced plasmas : concepts and applications / by Rashid A. Ganeev.
Description: First edition. | Hoboken, NJ : John Wiley & Sons, 2018. | Includes index. |
Identifiers: LCCN 2018013083 (print) | LCCN 2018029388 (ebook) | ISBN 9781119472353 (pdf) | ISBN 9781119472261 (epub) | ISBN 9781119472247 (cloth)
Subjects: LCSH: Laser plasmas. | Harmonics (Electric waves)
Classification: LCC QC718.5.L3 (ebook) | LCC QC718.5.L3 G375 2018 (print) | DDC 530.4/43-dc23
LC record available at https://lccn.loc.gov/2018013083
Cover design: Wiley
Cover image: © sakkmesterke/iStockphoto
Dedication
To my parents, wife, son, and daughter
Preface
The motivation in writing this book is to show the most recent findings of newly emerged field of resonance‐enhanced high‐order harmonic generation (HHG) using the laser pulses propagating through the narrow and extended laser‐produced plasma plumes. It becomes obvious that the developments in this field are aimed for improvement of harmonic yield through precise study of resonance effects during fine‐tuning of driving pulses to the resonances. The purpose of writing this book is to acquaint the readers with the most advanced, recently developed methods of plasma harmonics generation at the conditions of coincidence of some harmonics, autoionizing states, and some ionic transitions possessing strong oscillator strengths. This book demonstrates how one can improve the plasma harmonic technique using this approach.
There is a classical book relevant with the resonance processes in gaseous media [1]. Another book [2] is related with the spectroscopic details of nonlinear optical studies. Separate chapters of the nonlinear optical properties of matter [3] were related with the resonance processes. Some details of plasma properties relevant to those at which the resonance processes play an important role are discussed in Ref. [4]. Meanwhile, though some separate details of plasma harmonic studies were published in different edited books as the chapters, there is no collection of the various aspects of resonance‐enhanced harmonic generation processes in a single book.
The dissemination of information presented in this book will help to understand the peculiarities of laser–plasma interaction, which can be used for the amendment of harmonic yield in the extreme ultraviolet (XUV) region. The book also demonstrates the limitations of this method of harmonic generation, especially in the case of gas HHG. The development of plasma harmonic spectroscopy using this approach would be useful for material science. It may help in the next steps of the development of this interaction, which lead to generation of attosecond pulses. The basics of resonance plasma harmonic studies will help the reader to acquaint with novel methods of XUV coherent sources formation.
Among most attractive key features, which the reader may find in this book, are the demonstration of novel approaches in the resonance‐based amendments of harmonic generation in the laser‐produced plasmas using fixed and tunable long‐wavelength pulses, methods of the application of tunable laser sources of parametric waves for resonance enhancement of single harmonic, the application of proposed method for the nonlinear optical spectroscopic studies of various organic materials, and the implementation of theoretical and experimental consideration of the usefulness of mid‐infrared driving pulses and two‐color technique for the potential shortening of harmonic pulses toward the attosecond region.
The novelty in laser–plasma resonance interaction shown in this book may attract the interest in various groups of researchers, particularly those involved in the applications of lasers and development of short‐wavelength coherent sources. Most relevant audience include the researchers, specialists, and engineers in the fields of optics and laser physics. This book will also be useful for the students of high education in the physical departments of universities and institutes. It may serve as a tutorial for the optical and nonlinear optical interactions of ultrashort pulses and low‐dense plasmas produced on the surfaces of various solids.
This book would be interesting to the academic community. The researchers in laser physics and optics are the main audience, who can find interesting information regarding state‐of‐art developments in the field of frequency conversion of laser sources toward the short wavelength spectral range. Those involved in optics, nonlinear optics, atomic physics, resonance processes, HHG, and plasma physics are the specific potential readers of this book. Graduate students can also find plenty of novelties in this rapidly developing field of nonlinear optics and atomic physics. Any professionals interested in material science could be also interested in updating their knowledge of the new methods of material studies using nonlinear spectroscopy, developed using the resonance‐induced high‐order harmonic enhancement in the vicinity of autoionizing states and ionic transitions possessing strong oscillator strengths.
