An integrated external cavity laser composed of a UV written grating in a silica waveguide and a spot-size converted laser diode on Si

A single-mode, wavelength stabilized light source is a key device for a wavelength division multiplexing (WDM) system. The external cavity laser % with a UV written grating in silica fiber[l] or planar waveguide[2] is an attractive candidate since the oscillation wavelength, which is determined by the Bragg wavelength, is less dependent on temperature than that of single-mode semiconductor laser diodes. The introduction of such lasers into practical systems requires the integration of the laser diode and the UV written grating to ensure that they are stably coupled as this provides stable oscillation and makes mass production possible.