Photonic-chip-based tunable slow and fast light via stimulated Brillouin scattering.
ABSTRACT We report the first (to our knowledge) demonstration of photonic chip based tunable slow and fast light via stimulated Brillouin scattering. Slow, fast, and negative group velocities were observed in a 7 cm long chalcogenide (As(2)S(3)) rib waveguide with a group index change ranging from ~-44 to +130, which results in a maximum delay of ~23 ns at a relatively low gain of ~23 dB. Demonstration of large tunable delays in a chip scale device opens up applications such as frequency sensing and true-time delay for a phased array antenna, where integration and delays ~10 ns are highly desirable.
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ABSTRACT: Electromagnetically induced transparency (EIT) [1, 2] provides a powerful mechanism for controlling light propagation in a dielectric medium, and for producing both 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  has also been used successfully for the generation of slow and fast light [4-7]. However, EIT-type processes based on SBS were considered infeasible because of the short coherence lifetime of hypersonic phonons. Here, we demonstrate a new Brillouin scattering induced transparency (BSIT) phenomenon generated by acousto-optic interaction of light with long-lived propagating phonons [8, 9]. This transparency is intrinsically non-reciprocal due to the stringent phase-matching requirements. We demonstrate BSIT in a silica microresonator having a specific, naturally occurring, forward-SBS phase-matched modal configuration [8, 9]. BSIT is shown to enable extremely compact and ultralow power slow/fast light generation with delay-bandwidth product comparable to state-of-the-art SBS systems.08/2014;
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ABSTRACT: It is demonstrated that a heterodyne method can improve the measurement accuracy of the stimulated Brillouin scattering (SBS) gain spectrum. A method of adjusting signal light into the SBS gain region is also presented to take the SBS effect into account in comparatively low-standard equipment. The resolution to measure the optical spectrum is increased from about 1 GHz to 10 kHz. The 300 MHz width of light carrier of Gaussian function also results in a spectrum of modulated light of Gaussian function. If the heterodyne monitor is used to adjust signal light into the SBS gain region in our system, a maximum 32 ns delay is achieved in commercial-standard equipment with a Brillouin broadband of 600 MHz.Journal of Modern Optics 02/2013; 60(4):288-291. · 1.17 Impact Factor
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ABSTRACT: We theoretically and experimentally investigate the conditions of obtaining a narrowband flat-top Brillouin gain spectrum (BGS) based on single-frequency and multi-frequency phase modulations. Using the unequal-amplitude spectral lines, the flat-top BGS can be realized by controlling the intensity ratio and the frequency separation between them. In experiment, we obtain the flat-top gain spectra with the bandwidths of 40 MHz and 125 MHz, and with the top fluctuation of less than 0.21 dB. Based on this, we also achieve low distortion Brillouin amplification of a probe signal pulse and spectrum.Laser and Particle Beams 09/2013; 31(03). · 2.02 Impact Factor