6 THZ RANGE TUNABLE 2.5 GB S FREQUENCY-CONVERSION BY A MULTIQUANTUM-WELL Y-LASER/

We report on improved monolithic interferometric semiconductor lasers in Y configuration. When operated as an electronically tunable light s ource, single longitudinal mode emission with a very large CW tuning r ange up to 51 nm is accessed. By using all-quaternary compressively st rained MQW active layers also low dc threshold currents down to < 10 m A per segment are obtained (i.e., < 40 mA for the total 1500 mum long and branched device being pumped uniformly). New asymmetrical Y laser configurations are studied which exhibit simplified current control sc hemes allowing for improved wavelength tuning response. Single current step tuning spans up to 8 nm range. In the all-optical wavelength con verter operation mode the wide tunability of Y lasers across the whole spectrum of the semiconductor gain profile can be fully exploited. Ul trawide range tunable frequency conversion up to 6 THz within the 1550 nm wavelength window including blue and red shift is demonstrated. Hi gh-speed 2.5 Gb/s data streams are converted with 10(-9) BER.