NOVEL HYBRID INTERFEROMETER STABILIZATION SCHEME USED IN WAVELENGTH SHIFT MEASUREMENT FOR BRAGG GRATING SENSORS

A novel hybrid interferometer stabilization scheme used for wavelength shift measurement, such as for in-fiber Bragg grating-based sensors, is described. This scheme combines the advantages of the long term opt ical imbalance stability offered by the locking system used and a comp arative insensitivity to vibration-induced noise at frequencies up to 200 Hz, achieved with the use of a so-called ''detection-and-compensat ion'' scheme. By including an additional reference beam and the hybrid interferometer stabilization scheme, the vibration-induced fluctuatio n in the signal can be reduced by about 20 dB, and the value of the ph ase variation can be reduced by a factor of 20. (C) 1998 American Inst itute of Physics.