High-performance tunable semiconductor laser based on silicon nitride external cavity

The invention provides a high-performance tunable semiconductor laser based on a silicon nitride external cavity. The structure comprises a laser gain chip, a spot size converter, a micro-ring resonator, a phase converter, a micro-ring phase modulator, an MZI coupler, an MZI transmission arm and a tunable loop reflector. An optical signal generated by the laser gain chip is transmitted into the micro-ring resonator through the spot size converter and the phase converter, the micro-ring resonator outputs light meeting specific interference conditions from the micro-ring waveguide, optical phase adjustment and mode selection are carried out on the micro-ring through the micro-ring phase modulator, and the light is converged through the MZI coupler and the MZI transmission arm. According to the tunable semiconductor laser, a three-micro-ring structure is adopted, the problems that a traditional laser is limited in tuning range, low in integration level, large in waveguide loss and the like are solved, meanwhile,