We experimentally investigate optically amplified time-division-multiplexed polarization-insensitive fiber-optic Michelson interferometric (PIFOMI) sensor systems, using an erbium-doped fiber amplifier (EDFA) and a phase-generated carrier (PGC) demodulation technique. The influence of the EDFA on the extinction ratio (ER) of the light pulse and on the minimum phase-detection sensitivity (MPDS) is examined. We find that the EDFA acting as a preamplifier has limited usefulness because the highly amplified spontaneous emission (ASE) noise generated by the EDFA degrades the ER and the MPDS. However, both postamplifiers and in-line EDFA’s can work successfully. The MPDS of the unamplified time-division-multiplexed PIFOMI system with an ER of 33 dB was 2.4 × 10−5 rad/(Hz)1/2 at ∼1 kHz. For maintaining a MPDS of better than 3.4 × 10−5 rad/(Hz)1/2 at ~1 kHz, the worst ER’s for the postamplified and in-line amplified systems were 20 and 17.8 dB, respectively. The corresponding input signal peak power should be larger than −20 and −25 dBm for the postamplifiers and in-line amplifiers, respectively. When two postamplifiers and two in-line amplifiers are used, an allowable sensor system loss of 47 dB and a link length of the input–output lead fiber of 108 km can be realized for this system with a 32-sensor array. Implementation of optically amplified time-division-multiplexed and wavelength-division multiplexed–time-division multiplexed PIFOMI subarray sensor systems are also addressed.
© 1998 Optical Society of America
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(060.4230) Fiber optics and optical communications : Multiplexing
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(130.6010) Integrated optics : Sensors
Yung-Kuang Chen, Pi-Cheng Law, and Shih-Chu Huang, "Experimental Investigation of an Optically Amplified Time-Division-Multiplexed Polarization-Insensitive Fiber-Optic Michelson Interferometric Sensor System," Appl. Opt. 37, 6615-6622 (1998)