Propagation of optical pulses in a resonantly absorbing medium: Observation of negative velocity in Rb vapor

Tanaka, Hirokazu; Niwa, H.; Hayami, Kana; Furue, S.; Nakayama, Kazunori; Kohmoto, T.; Kunitomo, M.; Fukuda, Yukio

doi:10.1103/physreva.68.053801

Cited by 62 publications

(46 citation statements)

References 20 publications

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“…We show that this is possible by changing a single experimental parameter. seen, as observed in previous work [7,8,9]. A far off-resonant pulse is shown in 2(b)-(d).…”

Section: Propagation Of Optical Pulsessupporting

confidence: 71%

“…However, this requires intensities above saturation and the near-resonant character of the process leads to higher order terms in the dispersion resulting in considerable pulse distortion. Slow light has also been studied in off-resonant optical systems, utilising Doppler-broadened absorption resonances [7,8,9]. In such systems, group indices of ∼ 10 3 are achievable, with GHz pulse bandwidths.…”

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confidence: 99%

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A gigahertz-bandwidth atomic probe based on the slow-light Faraday effect

et al. 2009

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The ability to control the speed and polarisation of light pulses will allow for faster data flow in optical networks of the future. Optical delay and switching have been achieved using slow-light techniques in various media, including atomic vapour. Most of these vapour schemes utilise resonant narrowband techniques for optical switching, but suffer the drawback of having a limited frequency range or high loss. In contrast, the Faraday effect in a Doppler-broadened slow-light medium allows polarisation switching over tens of GHz with high transmission. This large frequency range opens up the possibility of switching telecommunication bandwidth pulses and probing of dynamics on a nanosecond timescale. Here we demonstrate the slow-light Faraday effect for light detuned far from resonance. We show that the polarisation dependent group index can split a linearly polarised nanosecond pulse into left and right circularly polarised components. The group index also enhances the spectral sensitivity of the polarisation rotation, and large rotations of up to 15π rad are observed for continuous-wave light. Finally, we demonstrate dynamic broadband pulse switching, by rotating a linearly polarised nanosecond pulse from vertical to horizontal with no distortion and transmission close to unity.

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“…We show that this is possible by changing a single experimental parameter. seen, as observed in previous work [7,8,9]. A far off-resonant pulse is shown in 2(b)-(d).…”

Section: Propagation Of Optical Pulsessupporting

confidence: 71%

mentioning

confidence: 99%

A gigahertz-bandwidth atomic probe based on the slow-light Faraday effect

et al. 2009

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“…Many researchers have considered using gain doublets in the context of pulse advancement [19,20,21,22,23], and Macke and Segard [22] have discussed pulse advancements for absorptive doublets. Grischkowsky [24] measured the delay of a pulse between two Zeemanshifted absorbing resonances, and Tanaka et al [25] performed initial measurements of the delay of a pulse between two atomic hyperfine resonances. This work considers both delay and broadening with an emphasis on the suitability of the delay and broadening characteristics for practical applications.…”

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confidence: 99%

Low-distortion slow light using two absorption resonances

2006

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We consider group delay and broadening using two strongly absorbing and widely spaced resonances. We derive relations which show that very large pulse bandwidths coupled with large group delays and small broadening can be achieved. Unlike single resonance systems the dispersive broadening dominates the absorptive broadening which leads to a dramatic increase in the possible group delay. We show that the double resonance systems are excellent candidates for realizing all-optical delay lines. We report on an experiment which achieved up to 50 pulse delays with 40% broadening.A variety of applications in telecommunications and quantum information have been driving recent interest in slow group velocities of light pulses. Among these applications are continuously tunable delay lines, all-optical buffers [1], optical pattern correlation, ultra-strong crossphase modulation [2], low light level nonlinear optics [3,4,5], and numerous others. The means for obtaining ultra-slow group velocities have usually involved a Lorentzian transparency or gain resonance: electromagnetically induced transparency (EIT) [6,7,8,9,10], coherent population oscillations (CPO) [11,12,13], stimulated Brillouin scattering (SBS) [14,15,16], stimulated Raman scattering (SRS) [17,18] etc..In this paper we discuss delaying pulses whose center frequency lies between two strongly absorbing resonances. Many researchers have considered using gain doublets in the context of pulse advancement [19,20,21,22,23], and Macke and Segard [22] have discussed pulse advancements for absorptive doublets. Grischkowsky [24] measured the delay of a pulse between two Zeemanshifted absorbing resonances, and Tanaka et al. [25] performed initial measurements of the delay of a pulse between two atomic hyperfine resonances. This work considers both delay and broadening with an emphasis on the suitability of the delay and broadening characteristics for practical applications.In the context of optical delay lines, several criteria must be satisfied for slow light to be useful. First, the slowed light pulses must meet system bandwidth specifications. Second, the delay-bandwidth product must be much larger than unity. Third, the delay re-configuration rate should be faster than the inverse pulse propagation time through the medium. Fourth, pulse absorption must be kept to a minimum. Fifth, the pulse broadening should also be minimal. The exact requirements for practical optical buffers are application dependant. A typical system operating at 10 Gb/sec with return-tozero coding and a 50 % duty cycle might require 7.5 GHz signal bandwidth, a delay bandwidth product of 1000, a re-configuration rate in excess of 7.5 MHz with less than 90% absorption and pulse broadening of less than 2.Despite widespread interest in large pulse delays, simultaneously satisfying all five criteria for most applications has proven difficult. In this paper we show that double Lorentzian systems manages four of these criteria well: large bandwidth, large delay bandwidth product, minimal absorption and ...

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“…Considerable interest was also excited towards multiple experiments on the so called superluminal propagation in a medium (see, for example [5][6][7][8][9][10]) where an advance, as compared with vacuum, of the pulse peak value has been observed. Authors of these works interpret the obtained results as propagation of pulses at the velocity exceeding speed of light in vacuum and even at negative group velocity.…”

Section: Introductionmentioning

confidence: 99%

Short pulse propagation in an inverted two-level medium

Grigoryan

Chaltykyan

Paturyan

2011

Opt. Mem. Neural Networks

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Abstract-We consider propagation of a pulse carrying optical information in a resonant medium of two level atoms and revisit the concept of the group velocity. We obtain conditions when this concept may be used and show that in a population inverted medium the possible superluminal propagation may result in advance times much shorter than the pulse duration because of lethargic amplification following from the complete exact solution of the problem.

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Propagation of optical pulses in a resonantly absorbing medium: Observation of negative velocity in Rb vapor

Cited by 62 publications

References 20 publications

A gigahertz-bandwidth atomic probe based on the slow-light Faraday effect

A gigahertz-bandwidth atomic probe based on the slow-light Faraday effect

Low-distortion slow light using two absorption resonances

Short pulse propagation in an inverted two-level medium

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