Monolithic InP Ring Resonator based Laser with 40 kHz Linewidth and 40 nm Tuning Range

In this work, a narrow linewidth tunable laser based on ring resonators is presented. The ring resonators and a Sagnac loop total reflector are formed by low loss passive waveguides implemented in a monolithic InP photonic integrated circuit. The laser can be tuned to different wavelengths over a wavelength range from 1559 nm to 1602 nm and has a SMSR of above 36 dB. The output power coupled into a butt-coupled fiber reaches 6 mW for a current of 220 mA. The laser shows an intrinsic linewidth of 40.5 kHz.