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

Optics Letters

Enhanced optical precursors by Doppler effect via active Raman gain process

Yandong Peng, Yueping Niu, Lida Zhang, Aihong Yang, Lin Cheng Jiang, Shangqing Gong

Published Aug 3, 2012• 18 citations
Publisher

Abstract

A scheme for enhancing precursor pulse by Doppler effect is proposed in a room-temperature active-Raman-gain medium. Due to abnormal dispersion between two gain peaks, main fields are advanced and constructively interfere with optical precursors, which leads to enhancement of the transient pulse at the rise edge of the input. Moreover, after Doppler averaging, the abnormal dispersion intensifies and the constructive interference between precursors and main fields is much strengthened, which boosts the transient spike. Simulation results demonstrate that the peak intensity of precursors could be enhanced nearly 20 times larger than that of the input.

DOI
10.1364/ol.37.003333

Related papers

Extremely narrowed and amplified gain spectrum induced by the Doppler effect

Lida Zhang, Yun Jiang, Ren-Gang Wan +6 more

The effect of Doppler broadening on the gain spectrum is theoretically investigated in a hot N -type active Raman gain atomic system. It is found that the gain peak in the spectrum can be extremely narrowed and amplified by two orders at room temperature as compared with that in the cold atomic system. This remarkable result originates from the shift of the dressed levels and the modification to the transition probability between dressed states when the Doppler effect is considered in the hot atomic system. The enhanced subluminal and superluminal pulse propagation for the probe field in the hot atomic system has also been obtained by numerical simulation; the probe pulse undergoes no absorption and little pulse distortion.

Journal of Physics B Atomic Molecular and Optical Physics•Jun 21, 2011•17 citations

Enhanced gain and narrow linewidth of an optical cavity by the Doppler effect in a four-level atomic system

Yandong Peng, Aihong Yang, Huiyun Zhang +3 more

A scheme for high gain and narrow linewidth of an optical cavity with a four-level atomic system is proposed by the Doppler effect via active Raman gain (ARG) process. Atomic motion leads to Doppler frequency shift which induces constructive interference for the linear susceptibility. The enhanced normal dispersion greatly narrows the cavity linewidth, and the amplified gain gives rise to a high cavity transmission. Simulation results show that the cavity linewidth based on ARG is about one order of magnitude narrower than that based on electromagnetically-induced transparency under the same conditions, and the cavity transmission intensity could be enhanced by nearly 30 times.

Journal of Modern Optics•Jul 1, 2013•0 citations

Superluminal propagation of an optical pulse in a Doppler-broadened three-state single-channel active Raman gain medium

Kaijun Jiang, L. Deng, M. G. Payne

Using a single-channel active Raman gain medium, we show a $220\ifmmode\pm\else\textpm\fi{}20\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ advance time for an optical pulse of ${\ensuremath{\tau}}_{\mathit{FWHM}}=15.4\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{s}$ propagating through a $10\phantom{\rule{0.3em}{0ex}}\mathrm{cm}$ medium, a lead time that is comparable to what was reported previously using a two-mode pump field. In addition, we have verified experimentally all the features associated with this single-channel Raman gain system.

arXiv:quant-ph/0701164•Physical Review A•Sep 18, 2007•26 citations

Noticeable positive Doppler effect on optical bistability in an N-type active Raman gain atomic system

Zengguang Chang, Yueping Niu, Jingtao Zhang +1 more

We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.

Chinese Physics B•Nov 1, 2012•4 citations

An absorption-free and Doppler-improved optical waveguide for diffractionless light propagation

Ni Cui, Ziyang Gan, Lida Zhang

We propose a novel scheme to realize an optical waveguide induced by an active Raman gain (ARG) process in a four-level N-type atomic system. Because of the nature of the ARG, there are two distinct features related to the waveguide: i) It is not absorptive, on the contrary, weak gain is presented; ii) It can be improved by the Doppler effect in the sense that the dispersion is enhanced while the gain is further reduced. This is in sharp contrast to the previously considered schemes where usually the optical induced waveguide is passive and is severely attenuated by the Doppler effect. We then study the paraxial light propagation in the waveguide which shows that the propagation dynamics is lossless and diffractionless.

Scientific Reports•Oct 23, 2017•4 citations

Phase-controlled gain, phase shift, and group velocity using a room-temperature active-Raman-gain medium

Chao Hang, Guoxiang Huang

A four-level tripod active-Raman-gain scheme is analyzed for obtaining phase-controlled gain, phase shift, and group velocity at room temperature.The scheme can be used to eliminate significant probe field attenuation or distortion which is unavoidable in the scheme based on electromagnetically induced transparency.It is shown that the intensity gain, phase shift, and group velocity of a probe field can be simultaneously manipulated by changing the relative phase of two pump fields.The scheme is also different from that proposed recently by Deng et al.where a probe-field gain always exists.New features of the scheme presented here raise the possibility of designing rapidly responding optical switches and gates for optical information processing.

Chinese Optics Letters•Jan 1, 2009•0 citations
A scheme for enhancing precursor pulse by Doppler effect is proposed in a room-temperature active-Raman-gain medium. Due to abnormal dispersion between two gain peaks, main fields are advanced and constructively interfere with optical precursors, which leads to enhancement of the transient pulse at the rise edge of the input. Moreover, after Doppler averaging, the abnormal dispersion intensifies and the constructive interference between precursors and main fields is much strengthened, which boosts the transient spike. Simulation results demonstrate that the peak intensity of precursors could be enhanced nearly 20 times larger than that of the input.
The effect of Doppler broadening on the gain spectrum is theoretically investigated in a hot N -type active Raman gain atomic system. It is found that the gain peak in the spectrum can be extremely narrowed and amplified by two orders at room temperature as compared with that in the cold atomic system. This remarkable result originates from the shift of the dressed levels and the modification to the transition probability between dressed states when the Doppler effect is considered in the hot atomic system. The enhanced subluminal and superluminal pulse propagation for the probe field in the hot atomic system has also been obtained by numerical simulation; the probe pulse undergoes no absorption and little pulse distortion.
A scheme for high gain and narrow linewidth of an optical cavity with a four-level atomic system is proposed by the Doppler effect via active Raman gain (ARG) process. Atomic motion leads to Doppler frequency shift which induces constructive interference for the linear susceptibility. The enhanced normal dispersion greatly narrows the cavity linewidth, and the amplified gain gives rise to a high cavity transmission. Simulation results show that the cavity linewidth based on ARG is about one order of magnitude narrower than that based on electromagnetically-induced transparency under the same conditions, and the cavity transmission intensity could be enhanced by nearly 30 times.
Using a single-channel active Raman gain medium, we show a $220\ifmmode\pm\else\textpm\fi{}20\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ advance time for an optical pulse of ${\ensuremath{\tau}}_{\mathit{FWHM}}=15.4\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{s}$ propagating through a 10cm10\phantom{\rule{0.3em}{0ex}}\mathrm{cm}10cm medium, a lead time that is comparable to what was reported previously using a two-mode pump field. In addition, we have verified experimentally all the features associated with this single-channel Raman gain system.
We theoretically investigate the Doppler effect on optical bistability in an N-type active Raman gain atomic system inside an optical ring cavity. It is shown that the Doppler effect can greatly enhance the dispersion and thus create the bistable behaviour or greatly increase the bistable region, which has been known as the positive Doppler effect on optical bistability. In addition, we find that a positive Doppler effect can change optical bistability from the hybrid dispersion-gain type to a dispersive type.
We propose a novel scheme to realize an optical waveguide induced by an active Raman gain (ARG) process in a four-level N-type atomic system. Because of the nature of the ARG, there are two distinct features related to the waveguide: i) It is not absorptive, on the contrary, weak gain is presented; ii) It can be improved by the Doppler effect in the sense that the dispersion is enhanced while the gain is further reduced. This is in sharp contrast to the previously considered schemes where usually the optical induced waveguide is passive and is severely attenuated by the Doppler effect. We then study the paraxial light propagation in the waveguide which shows that the propagation dynamics is lossless and diffractionless.
A four-level tripod active-Raman-gain scheme is analyzed for obtaining phase-controlled gain, phase shift, and group velocity at room temperature.The scheme can be used to eliminate significant probe field attenuation or distortion which is unavoidable in the scheme based on electromagnetically induced transparency.It is shown that the intensity gain, phase shift, and group velocity of a probe field can be simultaneously manipulated by changing the relative phase of two pump fields.The scheme is also different from that proposed recently by Deng et al.where a probe-field gain always exists.New features of the scheme presented here raise the possibility of designing rapidly responding optical switches and gates for optical information processing.