Development of an automatic control and acquisition circuit for an optical phase-locked loop module used as a signal source in phased-array communications antennas

A fully automatic semiconductor-laser based Optical Phase Locked Loop (OPLL) subsystem has been developed using a packaged OPLL module and custom electronic circuits. The OPLL module contains a DFB laser and a multi-section tuneable laser operating at 1500 nm. The custom circuits perform the operations required to control the bias currents and temperatures of the lasers. When the subsystem is activated, the emission frequency of one of the lasers is slowly tuned to match the other laser emission frequency, thus beginning the locking process. A fibre coupler taps off a small part of the OPLL module output and detects the laser beat signal in an optical receiver. When this frequency matches that of the input LO signal to the OPLL module, the circuit detects the locked state and ensures that it is maintained. This paper details the design and implementation of the OPLL control and acquisition circuits, together with the performance of the OPLL subsystem.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.