Frequency stability in high speed frequency switching of digitally tunable laser using ladder filter

A monolithically integrated digitally tunable ring laser has been developed that employs a ladder filter and a ring resonator. The ladder filter selects one channel from the periodic channels of the ring resonator and the stable device performance is achieved by adopting a chirped ladder filter with one dominant passband. The device is capable of 34-channel (100-GHz spacing) digitally tunable laser operation and the sidemode suppression ratio is more than 40 dB. The switching time for any wavelength is less than 10 nsec and the frequency drift caused by the thermal transient is less than 500 MHz