Th. Barnes et al., 'Best-case' noise performance of feedback interferometers, potential for micromachine applications, OPT LASER E, 32(5), 1999, pp. 485-495
We present a theoretical analysis of the noise performance of phase measuri
ng feedback interferometers. We first analyse the operation of this kind of
instrument and note that under certain circumstances bistability can occur
. The bistable region should be avoided if possible when using feedback int
erferometry for high-accuracy measurement with low-input powers, as it can
give rise to very high-noise levels. We then go on to investigate the effec
ts of shot noise (on the interferometer output signal) and thermal noise (i
n the feedback loop), and relate these to the phase measurement accuracy of
the interferometer, A 'best-case' calculation indicates that phase noise o
f about 0.005 lambda is possible at input powers in the nanowatt region. In
practice, we expect that noise levels will be higher than predicted (parti
cularly at high-input powers) due to the effects of vibration and air turbu
lence. (C) 2000 Elsevier Science Ltd. All rights reserved.