The paper describes a technique for minimising the retro-reflections from pulsed-reflectometric optical fibre sensors which may return into a single mode semiconductor laser source. The reported system is pulsed using a Bragg cell, whose drive signal is adjusted to ensure that it does not diffract when light returns from the sensor thereby preventing re-entry into the laser. Using this technique, together with feedback control of the laser drive current, spectral purity and low phase noise of the source can be maintained.
J. P. Dakin,
P. B. Withers,
"Progress Towards A Low Phase Noise Source For Fibre Optic Sensors", Proc. SPIE 0630, Fibre Optics '86, (6 October 1986); doi: 10.1117/12.963609; https://doi.org/10.1117/12.963609