TUNABLE LASER COMPRISING A MULTIPLE RING RESONATOR AND HIGHER ORDER MODE BLOCKING FILTER

摘要

A tunable laser has a multiple ring resonator comprising a plurality ofring resonators having respective ring-shaped waveguides and respectivedifferent optical path lengths, an input/output side optical waveguide coupledto the multiple ring resonator, an optical input/output device such as a laserdiode coupled to the input/output side optical waveguide, a reflection sideoptical waveguide coupled to the multiple ring resonator, an optical reflectorcoupled to the reflection side optical waveguide, a wavelength varyingmechanism for changing the resonant wavelength of the multiple ringresonator, and a filter for preventing light in high-order modes from beingintroduced into the multiple ring resonator and for propagating light in afundamental mode in the multiple ring resonator.