Narrow-linewidth thermally tuned multi-channel interference widely tunable semiconductor laser with thermal tuning power below 50 mW

A thermally tuned multi-channel interference widely tunable semiconductor laser is designed and demonstrated,for the first time to our knowledge, that realizes a tuning range of more than 45 nm, side-mode suppression ratios up to 56 d B, and Lorentzian linewidth below 160 k Hz. Al Ga In As multiple quantum wells (MQWs) were used to reduce linewidth, which have a lower linewidth enhancement factor compared with In Ga As P MQWs. To decrease the power consumption of micro-heaters, air gaps were fabricated below the arm phase sections. For a 75μm long suspended thermal tuning waveguide, about 6.3 m W micro-heater tuning power is needed for a 2πround-trip phase change. Total micro-heater tuning power required is less than 50 m W across the whole tuning range, which is lower than that of the reported thermally tuned tunable semiconductor lasers.