Intrinsic picosecond stimulated emission and emission-excited picosecond
optoelectronic nonlinear effects in GaAs
The above title is the
subject of long-term studies carried out in Kotelnikov IRE RAS. Some of them are
made in collaboration with V.I.
Perel and other scientists from the A.F. Ioffe FTI RAS, SCLI VSU, and K.I.
Satpayev KNRTU. The experiments were performed at room
temperature. We studied the processes occurring in a thin (~ 1 µm) GaAs layer, pumped by a powerful picosecond light
pulse. The discovered physical phenomena are listed
in Sections I-IV. In Section V, a laser picosecond spectro-photo-chronometric complex
is described, with which the studies were carried out. In Section VI a list of major publications is given. In the end, contact
data of IRE employees who performed the study is presented.
intrinsic picosecond stimulated emission of GaAs (hereinafter referred to
change of bleaching (increasing transparency) spectrum of GaAs and therefore of
the density of electron-hole plasma (EHP) - a sign of appearance of the picosecond
stimulated emission during picosecond pumping [1,2][*]
threshold emission of GaAs; its spectrum; the energy of its spectral components
as a function of energy monopulse pumping and the delay between the two pump
Area of light
amplification in the spectrum of fundamental light absorption in photo-pumped
GaAs [4*,▲,●,5]. The threshold of
anisotropy of the s-emission [6°].
"flare-up" [4*,▲,●,7] and exponential
relaxation of s-emission, determined by EHP cooling [7,8]. Sub-gigawatt intensity
of s-emission [9°].
slowing of picosecond stimulated radiative recombination of charge carriers at
increasing of the diameter of photo pumped region .
Characteristic for the
stimulated emission dependence of the spectrum of s-emission on the active
region diameter and on the pump picosecond pulse energy .
dependence of the longwave boundary of the s-emission spectrum on the energy
density of s-emission due to renormalization of the band gap caused by Coulomb
interaction of charge carriers (RBGC) .
scattering (SRS) of s-emission and picosecond pumping, which occurs with the
participation of optical plasmons [11,12]. This proves the activity of s-emission in
relation to the SRS.
Nonlinear dynamics of
long-wavelength edge of s-emission spectrum .
dependence of the moment of the beginning of s-emission flare-up on the energy
of its photon .
self-modulation of s-emission spectrum – a new modification of the effect of
competition and switching of spectral modes (CSSM) .
matched self-modulation of characteristics of s-emission emerging from the end
of the sample [15°].
plasma (EHP) threshold state, supported by s-emission.
residual bleaching of GaAs and threshold state of the EDP at the end of s-emission
Overthreshold state of
the EHP during s-emission [4*,▲,●,5].
The relationship between
the density of the EHP and its temperature at overthreshold and threshold states
Reversible picosecond change of the density
and temperature of EHP [2*,▲,●] and of GaAs bleaching [1*,▲,●].
An abnormal dependence of reversible
threshold bleaching of GaAs on the pump photon energy. Influence of GaAs
prebleaching on reversible change in its transparency [17▲,●].
A single parameter, i.e., the EHP density,
determines: (a) distribution of electrons between the valleys, (b) narrowing of
the band gap width due to Coulomb interaction of charge carriers in Γ-valley,
and (c) energy of the optical plasmon .
S-emission-created picosecond depletion of the
populations of energy levels of non-equilibrium electrons.
oscillations in the spectrum of fundamental light absorption in GaAs, displaying
the translation in the conduction band of the population depletion created by
s-emission at the bottom of the zone [18°].
correlation" between the spectrum of s-emission and self-modulation of the
light absorption spectrum in GaAs [6°].
Similarity of self-modulation
spectra of s-emission and light absorption .
of energy transport of electrons with emission of LO-phonons, leading to modulation
of the dependence of bleaching (consequently, EHP density) on the pumping photon
. For the formation of such a modulation is essential that EHP is in overthreshold
The influence of the energy transport of
electrons with radiation of LO-phonons on the amplitude, width and long-wavelength
edge of the s-emission spectrum, including appearance of modulation of the specified
spectrum parameters’ dependence on the energy ħωĺő [19,20]. Herewith the modulation of the long-wavelength
edge of the s-emission spectrum shows the modulation of the band gap width due
to interaction of electrons with LO-phonons, whose density oscillates with
The limit value of the s-emission spectrum width
in high-quality crystal as a function of the pump photon energy .
oscillations of population depletion of nonequilibrium electron energy levels,
arising in s-emission field and creating s-emission modulation. Self-synchronization
of the oscillations. (More detailed information is given
immediately below, as well as a list of received confirmations of this representation.)
distribution of electrons in the lower part of the conduction band in a highly pumped
thin GaAs layer is not like the Fermi one but is oscillatory. The depletions of
inverse populations of energy levels, which are “burned” by spectral modes of s-emission,
oscillate. The frequency of oscillations is determined, according to
perturbation theory, by the s-emission intensity. Oscillations are synchronized
in such a way as to ensure that their amplitude–phase–frequency characteristic
provided detailed equilibrium of the transitions of electrons between their
states. These transitions are an integral part of the stimulated Raman
scattering (SRS) of spectral modes of s-emission. Since SRS processes are bound
to be correlated for the above-mentioned detailed equilibrium, all these
processes can be included in the class of multiwave mixing in nonlinear optics.
The above-described oscillations of the populations naturally lead to the
modulation of s-emission. The same oscillations of populations are transferred
upward in the conduction band for detailed equilibrium upon electron–LO-phonon
interaction, which leads to self-modulation of the fundamental absorption of
light in GaAs. The height to which oscillations are translated depends on the
degree of screening of the electron–LO-phonon interaction by charge carriers,
i.e., on the density of the latter.
Mutually-matched self-modulation of the s-emission
characteristics, specified in section I, paragraph 11.
of the absorption spectrum of the probing picosecond light pulse [21°], periodic
in the spectrum [22°],
in time [23°],
and pump energy variation .
Experimental amplitude-phase-frequency response
of absorption self-modulation [25°].
Adapted analytical expression of the
perturbation theory, satisfactorily describing the experimental dependence of the frequency of population depletion self-oscillations
on s-emission intensity [9°].
Oscillations of the absorption of the probing
(p) picosecond light pulse with a fixed photon energy caused by interaction between
p-pulse and s-emission .
Self-synchronization of those modulations
of electron energy level populations, that are generated by: (a) a picosecond
probing light pulse and a spectral component of s-emission, (b) different
spectral components of s-emission .
Transitions of carriers between energy
levels that occur during SRS of s-emission spectral components [9°,14].
Signs of the formation of domain structure at
synchronization of population modulation .
equipment for experiments
Experiments are carried
out on the laser picosecond-range spectral-photo-chronometrical complex with
automatic system of measuring and processing physical parameters. In its
original form, the complex was manufactured in SCLI VSU. After the last essential upgrade (April 2012), the complex is
composed of the following components.
Driving YAG-laser PL
PDP1-300 ("SynchroTech", Russia), which generates single pulses of
= 1.064 µm, with controlled repetition
rate and duration varied in the range T = 22 - 32 ps. Pulse energy
instability 2%, duration T < 2 ps.
of pulses generated by the driving laser, total energy gain ~102.
frequency doublers for amplified pulses.
Two optical parametric
oscillators (OPO) on LiNbO3 with temperature wavelength
adjustment. For certain experiments, a third OPO with angular wavelength
adjustment is additionally installed. The first two OPO are pumped with pulses
of double frequency (wavelength
= 0.532 µm),
the third OPO – with pulses of = 1.064 µm. Pulses generated by each OPO are passed through
separate channels and focused on a single pot of sample. These pulses are used
for various pumping, for probing in “pump-probe” experiments, for EHP heating
by means of intraband light absorption, etc.
During experiments, time delay of sample irradiation by pulse, pulse wavelength
in the range 0.35 - 2.0 µm and its energy are adjusted independently for each
channel. Pulse duration (FWHM) 10 ps.
SpectraPro-2500i, able to operate in dispersion
adding mode by spectral measurements and in dispersion subtraction mode by
envelope (chronogram) measurements of separate spectrum components of
picosecond light pulse. The latter mode ensures that the duration of emission
component at spectrograph output is the same as at the input.
CCD-camera “PIXIS”, mounted at the second output slit of the first stage of
double spectrograph. Allows instantaneous measurements of integrated-over-time
spectrum of ultrashort optical emission. Measurement resolution from 0.3 nm (in
160 nm-wide range) to 0.05 nm (in the range of 30 nm width). For measurements
in dispersion adding mode, photomultiplier is mounted at the output slit of the
second stage of spectrograph.
Streak-camera PS-1/S1, that works together with CCD-camera “CoolSNAP”, is connected to the second output slit of double
spectrograph and allows to measure chronograms of picosecond light pulse
components, selected by spectrograph, with resolution no worse than 2 ps.
Dynamic range of such measurements is 10 to 30, depending on light wavelength
and pulse duration. Jitter (sweep start instability) is
ps, and it is automatically compensated online by data acquisition.
Streak-camera PS-1/S1 is designed and manufactured by Prokhorov General Physics
Institute of RAS.
automatic registration and control, where: (a) physical quantities are measured
and processed online, measurement accuracy estimated, and the results are
delivered to imaging facilities; (b) light pulse delay lines, shutters of pulse
propagation channels, spectrograph SpectraPro-2500i, two CCD-cameras ("PIXIS" and
"CoolSNAP"), and photomultiplier are
controlled. All these functions are realized with a special interface and a
powerful computer program.
The complex gives the following
possibilities. 1) Various kinds of sample pumping, including combined,
synchronous or with adjustable time delay (no worse than 0.3 ps precision), by
three pulses with specially adjusted photon energies and with various light
intensity and various dimensions of focus spot on the sample. 2) Instantaneous
measurement of time-integrated spectrum of ultrashort emission. The latter is
particularly necessary when investigated feature preserves its spectral
position on duration of emission pulse, and herewith experiment conditions
require multiple spectrum measurements. 3) Measurements of variations of
optical absorption, transparency and reflection during and after sample
pumping. Measurements are carried out by pump-probe method in two variants.
In the first variant, variations of probing pulse energy and its
time-integrated spectrum, caused by sample pumping, are measured. In the second
variant, chronogram of the whole probing pulse or of some of its spectral
components is measured. 4) Measurements of chronograms of separate spectral
components of intrinsic emission of sample. These chronograms also allow us to
reconstruct time evolution of spectrum of ultra-short intrinsic emission.
Eventually, the complex provides a rare combination of unique
technical possibilities for: ultrafast creation of powerful stimulated emission
in GaAs with various parameters, simultaneous excitation of ultrafast processes
of interaction of the emission with semiconductor, diversified optical
investigation of these processes. And all that practically without heating the
Note that before designing the streak-camera PS-1/S1 in Prokhorov GPI RAS, together with the scientists of this institute we had to
lead joint study of accuracy of picosecond light pulse measurements by
streak-cameras. Non-trivial methods and results of this study are published in
VI. The list of cited articles employees
I.L. Bronevoi, R.A. Gadonas,
V.V. Krasauskas, T.M. Lifshits, A.S. Piskarskas, M.A. Sinitsyn, B.S. Yavich. JETP
Lett., 42, ą8, 395 (1985).
I.L. Bronevoi, S.E.
Kumekov, V.I. Perel. JETP Lett., 43, ą8, 473 (1986).
N.N. Ageeva, I.L. Bronevoi, E.G. Dyadyushkin, B.S. Yavich. JETP
Lett., 48, ą5, 276 (1988).
N.N. Ageeva, I.L. Bronevoi, E.G. Dyadyushkin, V.A. Mironov, S.E. Kumekov, V.I. Perel’. Sol.
St. Commun., 72, 625 (1989).
I.L. Bronevoi, A.N.
Krivonosov, T.A. Nalet. Sol. St. Commun. 98, 903 (1996).
N.N. Ageeva, I.L. Bronevoi,
A.N. Krivonosov, S.E. Kumekov, S.V. Stegantsov. Semiconductors, 36, 136
N.N. Ageeva, I.L.
Bronevoi, D.N. Zabegaev, A.N. Krivonosov. JETP, 2013, Vol. 116, No. 4, pp.
I.L. Bronevoi, A.N.
Krivonosov. Semiconductors, 32, 484 (1998).
In the article on page 543, right
column, line 4 from top, in the expression (1) erroneously printed
μe = µh
≈ Eg, while should be μe – µh ≈ Eg.
N.N. Ageeva, I.L.
Bronevoi, D.N. Zabegaev, A.N. Krivonosov. Semiconductors, 44, 1121
10. I.L. Bronevoi, A.N. Krivonosov.
Semiconductors, 32, 479 (1998).
11. N.N. Ageeva, I.L. Bronevoi, A.N.
Krivonosov. Semiconductors, 35, 67 (2001).
12. I.L. Bronevoi, A.N. Krivonosov, V.I.
Perel’. Sol. St. Commun., 94, 363 (1995).
13. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. Semiconductors - in print.
14. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. JETP, 117, No. 2, 191
15. N.N. Ageeva, I.L. Bronevoi, A.N. Krivonosov,
S.E. Kumekov, T.A. Nalet, S.V. Stegantsov. Semiconductors, 39, 650
16. N.N. Ageeva, V.B. Borisov, I.L. Bronevoi, V.A.
Mironov, S.E. Kumekov, V.I. Perel, B.S. Yavich, R. Gadonas. Sol. St. Com., 75,
17. N.N. Ageeva, I.L. Bronevoi, V.A. Mironov, S.E.
Kumekov, V.I. Perel’. Sol. St. Com., 81, 969 (1992).
18. I.L. Bronevoi, A.N. Krivonosov, V.I.
Perel’. Sol. St. Commun., 94, 805 (1995).
19. I.L. Bronevoi, A.N. Krivonosov.
Semiconductors, 33, 10 (1999).
20. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. Semiconductors, 46, 921 (2012).
21. N.N. Ageeva, I.L. Bronevoi, A.N.
Krivonosov, S.V. Stegantsov. Semiconductors, 40, 785 (2006).
22. N.N. Ageeva, I.L. Bronevoi, A.N.
Krivonosov, T.A. Nalet, S.V. Stegantsov. Semiconductors, 41, 1398
23. N.N. Ageeva, I.L. Bronevoi, A.N. Krivonosov,
T.A. Nalet. Semiconductors, 42, 1037 (2008).
24. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. Semiconductors, 44, 1285 (2010).
25. N.N. Ageeva, I.L. Bronevoi, A.N.
Krivonosov. Semiconductors, 42, 1395 (2008).
26. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. JETP, 120, 664 (2015).
27. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov. Semiconductors, 50,
28. N.N. Ageeva, I.L. Bronevoi, D.N. Zabegaev,
A.N. Krivonosov, N.S. Vorob’ev, P.B. Gornostaev, V.I. Lozovoi, M.Ya. Schelev. Instrum.
Exp. Tech., 54 (4), 548 (2011).
29. N.N. Ageeva,
I.L. Bronevoi, R. Gadonas, S.E. Kumekov, V.A. Mironov, V.I. Perel, B.S. Yavich. Lasers
and ultrafast Processes, 4,
30. N.N. Ageeva, I.L. Bronevoi, S.E. Kumekov, V.A.
Mironov, V.I. Perel' in: Mode-Locked Lasers and Ultrafast Phenomena, G.B.Altshuler,
Editor, Proc. SPIE. 1842, 70 (1992) (Review).
31. N.N. Ageeva, I.L. Bronevoi, A.N. Krivonosov,
S.E. Kumekov, V.I. Perel.
Bulletin of the
Russian Academy of Sciences: Physics, 58, ą7, 89 (1994).
32. N.N. Ageeva, I.L. Bronevoi, A.N. Krivonosov,
D.N. Zabegaev. Physica Status Solidi C. V.8 (4), 1211 (2011).
Senior researcher, Ph.D. N.N. Ageeva -
Senior researcher, Ph.D. A.N. Krivonosov -
Junior researcher, D.N. Zabegaev –
Principal researcher, Dr.Sci. I.L. Bronevoi -
Tel.: +7 (495) 629 34 04
[*], ▲, ●, ° The results marked with the above
icons are presented respectively in a brief interim reviews: , , ,