Compact Digitally Tunable Laser

We present a new design for a digitally tunable laser using two waveguide grating routers wirh different free spectral range. For an N-channel device both the number of required amplifiers and the number of required grating arms scale as the square root of N, resulting in a more compact device that previously demonstrated and extreme scaleability. Contrary to previously demonstrated devices with reduced number of amplifiers, all wavelength channels are multiplexed together in one common channel, allowing for a higher output power. Experimental results are presented.