S. Donati et M. Sorel, A PHASE-MODULATED FEEDBACK METHOD FOR TESTING OPTICAL ISOLATORS ASSEMBLED INTO THE LASER-DIODE PACKAGE, IEEE photonics technology letters, 8(3), 1996, pp. 405-407
We present an easy-to-implement method for measuring the isolation fac
tor of an optical isolator mounted in front of its laser diode chip. T
he method is based on phase-modulated feedback that is induced by a mo
veable mirror reflecting the emitted power back into the laser, and it
consists of measuring the intensity modulation of power that is found
to be well correlated to the round-trip attenuation. Measurement sens
itivities up to -80 dB in terms of isolation have been obtained. The m
ethod has been tested successfully for several kinds of laser diodes,
either FP or DFB with emission in first and third windows.