Narrow linewidth Brillouin laser based on chalcogenide photonic chip

Abstract

We present, to the best of our knowledge, the first demonstration of a narrow linewidth, waveguide-based Brillouin laser that is enabled by large Brillouin gain of a chalcogenide chip. The waveguides are equipped with vertical tapers for low-loss coupling. Due to optical feedback for the Stokes wave, the lasing threshold is reduced to 360 mW, which is five times lower than the calculated single-pass Brillouin threshold for the same waveguide. The slope efficiency of the laser is found to be 30%, and the linewidth of 100 kHz is measured using a self-heterodyne method.

Inducing and harnessing stimulated Brillouin scattering in photonic integrated circuits

“…The SBS gain profile for the photonic chip has a full-width-at-half-maximum bandwidth of ∼34 MHz [51], while the FSR of the ring resonator is ∼8.4 MHz, which implies that there are nearly four resonator modes in the gain profile [153]. The cavity mode for which the gain equals the loss will start lasing first.…”

Low-power, chip-based stimulated Brillouin scattering microwave photonic filter with ultrahigh selectivity

“…Although SBS has been widely studied in optical fibers, recently there has been a growing interest in harnessing SBS in nanophotonic waveguides [22][23][24][25][26][27]. The ability to control the coherent interaction of photons and acoustic phonons in chip-sized devices (as opposed to in optical fibers many kilometres long) promises not only fascinating new physical insights, but also opens the path to realising key technologies on-chip including slow light [28,29]; narrow linewidth lasers [30]; optical frequency combs [31,32]; RF signal processing [33][34][35] and filtering [36][37][38][39][40]. In particular, SBS filters can exhibit linewidths of the order of 10-100 MHz.…”

On-chip stimulated Brillouin scattering and its applications

“…5(a)), pump propagates through the chip only once before it is removed by a circulator whereas the Stokes signal recirculates in a ring comprising a 7cm long photonic chip and 10 m long silica fibre with chip acting as a gain medium. The laser demonstrated a threshold of 360 mW [10], which is nearly five times smaller than that for the single-pass geometry, and a slope efficiency of 30% (see Fig. 5(b)).…”

“…Here we review our recent work on exciting SBS in a chalcogenide photonic-chip [2][3][4] and its application to a number of signal processing tasks such as slow-and fast-light induced tunable delay [5], Brillouin dynamic gratings [6], microwave photonic filters [7][8][9] and Brillouin laser [10]. The key to these demonstrations was the large Brillouin scattering cross-section (g B ~ 0.74 x 10 -9 m/W) and small mode area (A eff ~ 2.3 µm 2 ) of the photonic chip [4], which resulted in large gain at low powers.…”