A 134 MHz bandwidth homodyne optical phase-locked-loop of semiconductor laser diodes

Experiments on homodyne phase-locking of 7.5-MHz spectral linewidth semiconductor laser diodes are reported. Using negative electrical feedback lasers (NEFLs) as master and slave lasers, of which the spectral linewidths were narrowed from 7.5 MHz to 150 kHz, phase-locking was successfully achieved. The bandwidths of optical phase-locking were between 500 kHz and 10 MHz. The estimated phase error variances were between 0.8 rad/sup 2/ and 0.5 rad/sup 2/, respectively. This is the first report of an optical phase-locked loop (OPLL) using NEFLs. A free-running laser diode was phase-locked to a highly coherent master laser with a very fast OPLL. This is the first experimental result to demonstrate an extremely wideband OPLL with a 134-MHz bandwidth. The estimated phase error variance was 0.15 rad/sup 2/. The total phase-locked power of the slave laser was 86% of output.<
>