6 THz range tunable 2.5 Gb/s frequency conversion by a multiquantum well Y laser

Improved monolithic interferometric semiconductor lasers in Y configuration are reported. When they are operated as electrically tunable light sources, single-longitudinal-mode emission with a very large CW tuning range up to 51 nm is obtained. By using all-quaternary compressively strained multi-quantum-well (MQW) active layers, low DC threshold currents down to <10 mA per segment are also obtained (i.e., <40 mA for the total 1500-μm-long and branched device being pumped uniformly). Asymmetrical Y laser configurations which exhibit simplified current control schemes allowing for improved wavelength tuning response are studied. Single-current-step tuning spans a range up to 8 nm. In the all-optical wavelength converter operation mode the wide tunability of Y lasers across the whole spectrum of the semiconductor gain profile can be fully exploited