Photonic chip based tunable slow and fast light via stimulated Brillouin scattering

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 (As2S3) 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.