We investigate novel approach, which improves the sensitivity of
gravitational wave (GW) interferometer due to stochastic resonance (SR)
phenomenon, performing in additional nonlinear cavity (NC). The NC is installed
in the output of interferometer before photodetector, so that optical signal
emerging interferometer incidents on the NC and passes through it. Under
appropriate circumstances a specific transformation of noisy signal inside the
NC takes place, which results in the increase of output signal-to-noise ratio
(SNR). As a result optical noisy signal of interferometer becomes less noisy
after passing through the NC. The improvement of SNR is especially effective in
bistable NC for wideband (several hundreds Hz) detection, when chirp GW signal
is detected. Then SNR gain reaches amount ~ 10. When detection bandwidth is
narrowed, the influence of SR mechanism gradually disappears, and SNR gain
tends to 1. SNR gain also tends to 1 when the NC is gradually transformed to
linear cavity. Proposed enhancement of SNR due to the SR is not dependent of
noise type, which is prevalent in interferometer. Particularly proposed
approach is capable to increase signal-to-displacement noise ratio.Comment: 24 pages, 10 figure