Phase-induced intensity noise in an incoherent Fabry-Perot interferometer and other recirculating devices

Laser phase-induced intensity noise limits the dynamic range of all kinds of recirculating structures under short coherence illumination. The shape of the power spectrum of this noise, while it is always periodic, depends on the device type. Recirculating delay lines and the reflecting Fabry-Perot interferometer (F-P) exhibit minimum noise at integer multiples of 1/(round-trip time), whereas the transmitting F-P shows maximum noise at exactly these frequencies. This phenomenon is theoretically analyzed, and expressions are given for the standard deviation, the autocovariance, and the power spectrum of that noise for a general recirculating structure. The important problem of laser phase-induced intensity noise for the F-P structure is studied in detail, theoretically and experimentally, in both reflecting and transmitting modes.