Non-reciprocal Brillouin scattering induced transparency

Abstract

Electromagnetically induced transparency (EIT) [1,2] provides a powerful mechanism for controlling light propagation in a dielectric medium, and for producing slow and fast light. EIT traditionally arises from destructive interference induced by a nonradiative coherence in an atomic system. Stimulated Brillouin scattering (SBS) of light from propagating hypersonic acoustic waves [3] has also been used successfully for the generation of slow and fast light [4][5][6][7]. However, EIT-type processes based on SBS were considered infeasible because of the short coherence lifetime of hypersonic phonons. Here, we report a new Brillouin scattering induced transparency (BSIT) phenomenon generated by acousto-optic interaction of light with long-lived propagating phonons [8,9]. We demonstrate that BSIT is uniquely non-reciprocal due to the propagating acoustic phonon wave and accompanying momentum conservation requirement. Using a silica microresonator having naturally occurring forward-SBS phasematched modal configuration [8,9], we show that BSIT enables compact and ultralow-power slow-light generation with delay-bandwidth product comparable to state-of-the-art SBS systems. [3,10,11] is a fundamental materiallevel nonlinearity occurring in all states of matter [12] in which two optical fields are coupled to a traveling acoustic wave through photoelastic scattering and electrostriction. The light fields scatter from the periodic photoelastic perturbation generated by the traveling acoustic wave, while simultaneously writing a spatiotemporally beating electrostriction force whose momentum and frequency matches the acoustic wave. Phase matching for SBS is thus defined by both 1 arXiv:1408.1739v2 [physics.optics] 11 Aug 2014 energy and momentum conservation, and is satisfied in back-scattering only by multi-GHz phonon modes in most solids. SBS is frequently used for optical gain [3,13], laser linewidth narrowing [14], optical phase conjugation [15], dynamic gratings [16], and even material characterization and microscopy [17][18][19][20][21][22]. The applications of SBS in superluminal and slow light experiments have been recognized as well [4][5][6][7]. However, unlike the case of electromagnetically induced transparency (EIT) [1,2], the generation of transparency with SBS has never been demonstrated. This is because in typical Brillouin scattering pump-probe systems the lifetimes of phonons at multi-GHz frequencies are much shorter than the photon lifetimes [3,23,24], effectively disabling the coherent interference of probe Stokes scattering and pump anti-Stokes scattering pathways. In a forward-scattering SBS system however, this lifetime relationship can be reversed by coupling the light fields through a low-frequency long-lived phonon mode as shown recently in the experimental demonstration of forward-SBS lasing [8] and Brillouin cooling [9]. Stimulated Brillouin scattering (SBS)Nonlinear optical processes such as EIT need to satisfy the energy-momentum conservation, leading to the phase-matching requirement. For...

On-Chip Strong Coupling and Efficient Frequency Conversion between Telecom and Visible Optical Modes

“…We further realize a saturated frequency conversion from telecom band to visible band with almost unit internal (0.14 external) conversion efficiency. Notably, the transparency window demonstrated here is close to GHz, which is orders of magnitudes larger than the bandwidth of previously demonstrated transparency [17][18][19][20] and wavelength conversion [24,25] induced by opto-mechanical interaction. This large bandwidth, together with a flexible working environment (ambient air -no need for cryogenic cooling or vacuum system), may be beneficial for applications including optical switches, isolators and frequency converters.…”

“…The nonlinear optic induced transparency (NOIT), as an analogue to electromagnetically induced transparency resulting from coherent photon-atom [5] or photon-phonon interactions [17][18][19][20], is reported. Due to the inherent phase matching condition, the χ (2) nonlinearity based coherent interaction and the accompanying NOIT phenomenon are non-reciprocal [19,20], which permits future applications such as non-magnetic, ultrafast optical isolators [21][22][23]. We further realize a saturated frequency conversion from telecom band to visible band with almost unit internal (0.14 external) conversion efficiency.…”

Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures

“…SBS is also a powerful tool for integrated photonics signal processing [21][22][23], and it has been applied to realize a chip-based optical gyroscope [24]. Moreover, at radio-frequency rates, the SBS damping rate is low enough in certain systems to enable cavity optomechanical effects [25] including optomechanical cooling [26] and optomechanical-induced transparency [27].…”

“…SBS is also a powerful tool for integrated photonics signal processing [21][22][23], and it has been applied to realize a chip-based optical gyroscope [24]. Moreover, at radio-frequency rates, the SBS damping rate is low enough in certain systems to enable cavity optomechanical effects [25] including optomechanical cooling [26] and optomechanical-induced transparency [27].This work studies a recent prediction concerning the fundamental linewidth (i.e., nontechnical noise contribution to linewidth) of the stimulated Brillouin laser (SBL). The analysis of fundamental fluctuations in Brillouin devices falls into a more general category of optomechanical oscillators in which phonons participate in the oscillation process [28,29].…”

Opto-acoustic phenomena in whispering gallery mode resonators

“…Stimulated Raman, Brillouin scattering, third harmonic generation and four-wave mixing have been successfully demonstrated in WGM resonators made of fused silica in the past decade [18][19][20][21][22] . Potential applications of silica WGM resonator based SBS ranging from Brillouin cooling, [23] microwave synthesizer, [24] low-noise laser, [25] light storage, [26] slow and fast light [27] have been recently demonstrated. Crystalline WGM resonators with ultrahigh Q factors have been fabricated using precision mechanical polishing methods [28] .…”