Semiconductor lasers in optical communication band with very broadband tunability

Because the optical fiber has the low-loss window covering from below 1300 nm to above 1600 nm, devices used for optical communication are required to have the broadband characteristics. Several types of non-identical multiple quantum wells had been experimented. One has five 6 nm In$_{0.67}$Ga$_{0.33}$As$_{0.72}$P$_{0.28}$ quantum wells and two 15 nm In$_{0.53}$Ga$_{0.47}$As quantum wells, bounded by 15 nm In$_{0.86}$Ga$_{0.14}$As$_{0.3}$P$_{0.7}$ quantum barrier. One type of the non-identical multiple quantum wells has been used to fabricate the semiconductor optical amplifiers for semiconductor lasers with broadband tunability. Inserting the semiconductor optical amplifier in an external-cavity configuration with a grating as the feedback, the external-cavity semiconductor laser is tunable from 1295 nm to 1570 nm, which covers almost the entire low-loss window of the optical fiber. Also, using reflected-type grating telescope configuration, we are able to simultaneously generate two wavelengths. The two lasing wavelengths are tunable from a few nm separation to 170 nm separation. Simultaneous generation of two wavelengths at 1344 nm and 1514 nm in optical communication band is demonstrated.