All- fiber polarimetric sensor

A compensated and stabilized all-fiber polarimetric sensor has been constructed from about 50 m of bowtie fiber. The interferometer exhibits a minimum detectable phase delay of 0.3 microrad/sq rt Hz and a minimum detectable strain of 5.2 x 10 to the -13th/sq rt Hz at 20 kHz. An SNR analysis is presented to weigh the relative merits of the all-fiber polarimetric and Mach-Zehnder interferometers. Although the polarimeter exhibits a reduced strain sensitivity, its simplicity of design, improved environmental immunity, and high SNR make it a worthy candidate for many fiber sensor applications. (C.D.)