Abstract

Simple and compact optoelectronic devices having the all-optical signal reshaping and regenerating (2R) functions are attractive to spread those functionalities over the future fiber-optic networks cost-effectively. One promising candidate from the ultimate performance point of view is the interferometric configuration of semiconductor optical amplifiers (SOA) at present. Indeed, an improvement in the optical signal to noise ratio by more than 20 dB was demonstrated for a 40 Gb/s RZ data signal of 2⁷ – 1 pseudo-random bit sequence (PRBS).¹ Although its excellences in the regenerating and reshaping performance as well as the operation speed are claimed, one needs several SOAs and a light source there and, therefore, the scheme seems rather complicated and costly. Another promising method has been offered by the optical signal injection scheme into a mode-locked monolithic laser diode (MLLD), which has realized an optical clock recovery action for the 3R regeneration of 20 Gb/s pulse trains.² However, this scheme relies on the mode locking operation, whose fixed repetition rate could lead to a potential drawback regarding the modulation format transparency. In this paper, we report on more flexible “digital” characteristics found out in a much simpler configuration with a single device of dual-mode laser diode (DMLD) utilized. Its static input/output (I/O) curve exhibits highly abrupt switching features in the µW-regime, whose characteristic shape is attractively similar to those of electrical inverters in logic circuits. This kind of I/O characteristics would potentially lead to the optical 2R inverter operation that is applicable not only to RZ but also to NRZ data streams. Its Gb/s-class inverter operations were achieved for two kinds of DMLD devices.

© 2002 Optical Society of America