Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Femtosecond nonlinear coherence spectroscopy of the blue band of GaN

Lap Van Dao, My Thi Tra Do, P. Eckle, Peter Hannaford

Published Jan 1, 2005• 0 citations
OpenAlex

Abstract

The nonlinear optical properties of an undoped GaN epitaxial layer have been investigated in the spectral region 400 - 450 nm using two-colour multiple-pulse photon echo measurements. Variation of the laser wavelengths and pulse sequence and the use of spectrally resolved measurements allows us to study the dephasing of the donors and acceptors and the energy relaxation properties for the blue band of GaN

Related papers

Femtosecond Nonlinear Coherence Spectroscopy of the Blue Band of GaN

Lap Van Dao, My Thi Tra Do, P. Eckle +1 more

The nonlinear optical properties of an undoped GaN epitaxial layer have been investigated in the spectral region 400 - 450 nm using two-colour multiple-pulse photon echo measurements. Variation of the laser wavelengths and pulse sequence and the use of spectrally resolved measurements allows us to study the dephasing of the donors and acceptors and the energy relaxation properties for the blue band of GaN

Conference on Optoelectronic and Microelectronic Materials and Devices (COMMAD)•Jan 25, 2006•0 citations

Femtosecond nonlinear spectroscopy investigation of the yellow band of GaN

Lap Van Dao, Martin Lowe, Peter Hannaford

The nonlinear properties of an undoped GaN epitaxial layer in the spectral region of the yellow band have been investigated using two- and three-pulse two-colour photon echo measurements. The optical nonlinearity induced by three sequential femtosecond pulses is studied on a short timescale (<500 fs) where free induction decay and photon echoes are the main contributions to the observed signal and on a long timescale (up to 20 ps) in the case of a population grating. Variation of the wavelength of the femtosecond pulses and the use of spectrally resolved measurements allows us to study the origin of the yellow band and the phase and energy relaxation properties of this band. The results suggest that the emission of light in the yellow band arises from recombination between shallow donors and deep acceptors and that the trapping time of carriers into defect levels is very short (<1 ps).

Journal of Physics B Atomic Molecular and Optical Physics•Apr 8, 2003•5 citations

Femtosecond three-pulse photon echo and transient grating studies of the yellow band of GaN

Lap Van Dao, Martin Lowe, Peter Hannaford

Using femtosecond three-pulse two-colour photon echo measurements we study the optical nonlinearity induced by pump and probe in the short time scale (< 500 fs) where the free induction decay and photon echo are the main contribution to observed signal and in a long time scale (up to 20 ps) in the trace of the population grating. The variation of the pump and probe wavelength and use of spectrally resolved measurements allows us to study the origin of the yellow band and the phase and energy relaxation properties of this band. The results suggest that the light emission in the yellow band is the recombination between shallow donors and deep acceptors and the carriers trapping time is very short.

Conference on Optoelectronic and Microelectronic Materials and Devices (COMMAD)•Aug 25, 2005•0 citations

Nonlinear spectral hole-burning of the intraband transition at 1.55 μm in GaN/AlN quantum dots

D. T. Nguyen, Maria Tchernycheva, François Henri Julien +3 more

GaN/AlN quantum dots are semiconductor nanostructures where the huge conduction band offset of 1.75 eV leads to intraband transitions at exceptionnaly short wavelengths compared to III-As semiconductor materials. For specific quantum dot dimensions, it was shown that the absorption spectrum covers the optical communication spectral range. The ultrafast relaxation dynamics observed for these materials motivates the development of opto-electronic devices, and especially ultrafast switches. However, a detailed insight into the microscopic processes governing the relaxation dynamics is still missing although of fundamental importance for the understanding and the optimization of the devices operation. In particular, there is no study of the homogeneous broadening which drives the saturation properties of GaN/AlN quantum dots-devices. In this paper, we present homogeneous linewidth measurements by means of the nonlinear optical technique of spectral hole-burning. Spectrally-resolved pump-probe experiments with cw-lasers allow us to characterize the coherence relaxation dynamics down to 5K by resolving the homogeneous linewidth in an ensemble of GaN/AlN quantum dots. The differential transmission measured at 5K for a TM-polarized pump shows a pronounced bleaching with an amplitude of 2x10-4 on a background signal of 5x10-5. According to the selection rules of the s-pz intraband transition in GaN/AlN QDs, we attribute the photoinduced increase of the probe transmission to the partial saturation of the quantum dots by the pump laser, and we deduce a homogeneous linewidth of 15 meV at 5K. We find that the differential transmission signal scales like the square-root of the incident pump power, thus revealing the importance of electron-electron scattering in the population relaxation dynamics. As a matter of fact, we find that the population relaxation from the pz excited state is predominantly governed by Auger-type processes whereas optical phonon emission only plays a minor role, even if it may contribute to secondary processes during the carrier cascade to the fundamental s state via intermediate confined states.

•Oct 15, 2012•0 citations

Time-resolved photon echoes from donor-bound excitons in ZnO epitaxial layers

S. V. Poltavtsev, Alexander N. Kosarev, Ilya A. Akimov +8 more

The coherent optical response from 140 nm and 65 nm thick ZnO epitaxial layers is studied using four-wave-mixing spectroscopy with picosecond temporal resolution. Resonant excitation of neutral donor-bound excitons results in two-pulse and three-pulse photon echoes. For the donor-bound A exciton (${\mathrm{D}}^{0}{\mathrm{X}}_{\text{A}}$) at temperature of 1.8 K we evaluate optical coherence times ${T}_{2}=33--50$ ps corresponding to homogeneous line widths of $13--19\phantom{\rule{0.222222em}{0ex}}\ensuremath{\mu}\mathrm{eV}$, about two orders of magnitude smaller as compared with the inhomogeneous broadening of the optical transitions. The coherent dynamics is determined mainly by the population decay with time ${T}_{1}=30--40$ ps, while pure dephasing is negligible. Temperature increase leads to a significant shortening of ${T}_{2}$ due to interaction with acoustic phonons. In contrast, the loss of coherence of the donor-bound B exciton (${\mathrm{D}}^{0}{\mathrm{X}}_{\text{B}}$) is significantly faster (${T}_{2}=3.6\phantom{\rule{0.16em}{0ex}}\mathrm{ps}$) and governed by pure dephasing processes.

arXiv:1702.05057•Physical review. B./Physical review. B•Jul 21, 2017•10 citations

Femtosecond dephasing of coherent excitation and ultrafast switching of resonant optical nonlinearity of molecular aggregates

Anatolii A. Ivanov, Mikhail V. Alfimov, Aleksei M. Zheltikov

One-and two-photon-resonant nonlinear-optical interactions of ultrashort laser pulses are employed to measure the dephasing time of coherent excitation and to investigate the ultrafast population dynamics of molecular aggregates. Dephasing of coherent excitation of molecular aggregates with a characteristic phase relaxation time of about 120 fs is visualized. Ultrafast switching of optical nonlinearity in molecular aggregates with a typical switching time of about 450 fs is demonstrated.

Journal of Experimental and Theoretical Physics Letters•Jul 1, 2006•0 citations
The nonlinear optical properties of an undoped GaN epitaxial layer have been investigated in the spectral region 400 - 450 nm using two-colour multiple-pulse photon echo measurements. Variation of the laser wavelengths and pulse sequence and the use of spectrally resolved measurements allows us to study the dephasing of the donors and acceptors and the energy relaxation properties for the blue band of GaN
The nonlinear properties of an undoped GaN epitaxial layer in the spectral region of the yellow band have been investigated using two- and three-pulse two-colour photon echo measurements. The optical nonlinearity induced by three sequential femtosecond pulses is studied on a short timescale (<500 fs) where free induction decay and photon echoes are the main contributions to the observed signal and on a long timescale (up to 20 ps) in the case of a population grating. Variation of the wavelength of the femtosecond pulses and the use of spectrally resolved measurements allows us to study the origin of the yellow band and the phase and energy relaxation properties of this band. The results suggest that the emission of light in the yellow band arises from recombination between shallow donors and deep acceptors and that the trapping time of carriers into defect levels is very short (<1 ps).
Using femtosecond three-pulse two-colour photon echo measurements we study the optical nonlinearity induced by pump and probe in the short time scale (< 500 fs) where the free induction decay and photon echo are the main contribution to observed signal and in a long time scale (up to 20 ps) in the trace of the population grating. The variation of the pump and probe wavelength and use of spectrally resolved measurements allows us to study the origin of the yellow band and the phase and energy relaxation properties of this band. The results suggest that the light emission in the yellow band is the recombination between shallow donors and deep acceptors and the carriers trapping time is very short.
GaN/AlN quantum dots are semiconductor nanostructures where the huge conduction band offset of 1.75 eV leads to intraband transitions at exceptionnaly short wavelengths compared to III-As semiconductor materials. For specific quantum dot dimensions, it was shown that the absorption spectrum covers the optical communication spectral range. The ultrafast relaxation dynamics observed for these materials motivates the development of opto-electronic devices, and especially ultrafast switches. However, a detailed insight into the microscopic processes governing the relaxation dynamics is still missing although of fundamental importance for the understanding and the optimization of the devices operation. In particular, there is no study of the homogeneous broadening which drives the saturation properties of GaN/AlN quantum dots-devices. In this paper, we present homogeneous linewidth measurements by means of the nonlinear optical technique of spectral hole-burning. Spectrally-resolved pump-probe experiments with cw-lasers allow us to characterize the coherence relaxation dynamics down to 5K by resolving the homogeneous linewidth in an ensemble of GaN/AlN quantum dots. The differential transmission measured at 5K for a TM-polarized pump shows a pronounced bleaching with an amplitude of 2x10-4 on a background signal of 5x10-5. According to the selection rules of the s-pz intraband transition in GaN/AlN QDs, we attribute the photoinduced increase of the probe transmission to the partial saturation of the quantum dots by the pump laser, and we deduce a homogeneous linewidth of 15 meV at 5K. We find that the differential transmission signal scales like the square-root of the incident pump power, thus revealing the importance of electron-electron scattering in the population relaxation dynamics. As a matter of fact, we find that the population relaxation from the pz excited state is predominantly governed by Auger-type processes whereas optical phonon emission only plays a minor role, even if it may contribute to secondary processes during the carrier cascade to the fundamental s state via intermediate confined states.
The coherent optical response from 140 nm and 65 nm thick ZnO epitaxial layers is studied using four-wave-mixing spectroscopy with picosecond temporal resolution. Resonant excitation of neutral donor-bound excitons results in two-pulse and three-pulse photon echoes. For the donor-bound A exciton (D0XA{\mathrm{D}}^{0}{\mathrm{X}}_{\text{A}}D0XA​) at temperature of 1.8 K we evaluate optical coherence times T2=33−−50{T}_{2}=33--50T2​=33−−50 ps corresponding to homogeneous line widths of $13--19\phantom{\rule{0.222222em}{0ex}}\ensuremath{\mu}\mathrm{eV}$, about two orders of magnitude smaller as compared with the inhomogeneous broadening of the optical transitions. The coherent dynamics is determined mainly by the population decay with time T1=30−−40{T}_{1}=30--40T1​=30−−40 ps, while pure dephasing is negligible. Temperature increase leads to a significant shortening of T2{T}_{2}T2​ due to interaction with acoustic phonons. In contrast, the loss of coherence of the donor-bound B exciton (D0XB{\mathrm{D}}^{0}{\mathrm{X}}_{\text{B}}D0XB​) is significantly faster (T2=3.6ps{T}_{2}=3.6\phantom{\rule{0.16em}{0ex}}\mathrm{ps}T2​=3.6ps) and governed by pure dephasing processes.