Widely tunable multichannel grating cavity laser

A widely tunable grating cavity laser based on the Rowland circle construction for a concave grating is proposed and demonstrated. The device is implemented by employing multichannel array structure in a Littman configuration and fabricated by integrating all elements in an InP substrate. Only one channel is turned on at a time, with coarse tuning realized by selecting the appropriate element in the channel array and fine tuning by controlling the beam deflection provided by dispersive element. An overall tuning range of 50 nm with a sidemode suppression ratio of more than 30 dB has been achieved for the six-channel device.