Abstract

Monolithic mode-locked semiconductor lasers are compact and reliable pulse sources for optical communication systems employing short pulses such as optical time division multiplexed systems and long distance soliton transmission [1]. These sources offer the advantage and flexibility for integration with filters, amplifiers, modulators, saturable absorbers, or other photonic components which can enhance the versatility and reliability of the transmission source [2,3]. However, the repetition rate at which the mode-locked laser operates is inversely proportional to the cavity length. Therefore, very long cavity lengths are required for operation at frequencies which are of practical interest for systems deployed today, such as those designed for the Sonet standard rate, OC-48 (2.488 Gbit/s). Maturing growth and processing techniques of III-V materials have enabled fabrication of very long 1.55 μm laser devices, that are suitable for mode-locking at repetition rates below 10 GHz [4]. Recent results indicate a trend toward lower, more practical operating frequencies and increased integration. Here, we report a semiconductor laser with a length twice that of any previously reported monolithic mode-locked laser. The resultant fundamental repetition rate is 2.2 GHz. Active mode-locking at the fundamental frequency, and at higher harmonics, yields optical pulses with widths ranging from 9.0-12.0 ps.

© 1993 Optical Society of America