A technique for monitoring interferometric sensors by correlation of the optical signal from the sensor with the signal from a phase-modulated reference interferometer is described. The technique is applied to temperature measurement with a fiber Fabry–Perot sensing head. We extend the 7 °C unambiguous measurement range obtained with a 1.3-μm laser diode as the light source to 43 °C by adding a second laser diode emitting at 1.55μm . Experimentally, a rms phase-measurement error of ±0.28rad , corresponding to a temperature error of ±0.32°C , was achieved with a low-quality multimode Fabry–Perot laser. The phase error was improved to ±0.14rad , corresponding to a temperature error of ±0.16°C , by use of a distributed-feedback laser diode.
© 1999 Optical Society of America
(060.2310) Fiber optics and optical communications : Fiber optics
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(120.2230) Instrumentation, measurement, and metrology : Fabry-Perot
J. X. Fang and H. F. Taylor, "Accurate monitoring of an interferometric fiber-optic sensor with a multimode semiconductor laser," Opt. Lett. 24, 522-524 (1999)