An interferometric technique for measuring the frequency response of optical detector-amplifier combinations

The frequency response of optical detector-amplifier combinations has been measured by transducing a low-frequency wavelength modulation of the source to a higher frequency intensity modulation using an interferometer with unbalanced optical paths. Measurements for several detector circuits are presented for the frequency range DC to about 30 MHz using both a bulk optic Michelson interferometer and a low-finesse Fabry-Perot interferometer constructed from high-birefringence optical fibre. Experimental results are compared with direct intensity modulation of the source and also with a circuit simulation using PSpice.