Mode couplings due to external forces distributed along a polarization-maintaining fiber: an evaluation

Abstract

A new interferometric scheme for measuring mode conversion distributed locally along a polarizationmaintaining fiber is presented. Using this technique the power coupling coefficient, varying with magnitude and angle of external pressure transversely applied to a fiber, was evaluated both theoretically and experimentally. The coupling point location is determined with +/- 1.5-cm accuracy and resolution of better than 10 cm for a 220-m long fiber having modal birefringence of 4.4 x 10 (- 4). The coupling coefficient was proportional to the external force in the range from 5 x 10 (- 3) to 0.1 kg/mm. The relationships determined experimentally reflected those predicted by theory.

<title>Improvement of resolution and elimination of crosstalk for white-light distributed sensing system</title>

“…The fiber amplitude noise h1 is at the level of 1O n? [3 The spurious signal S represents the crosstalk among coupling units at 4…”

<title>Distribution sensing by synthesis of the optical coherence function</title>

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<title>Practical birefringent fiber Sagnac ring force sensor</title>

“…1 , can be chosen as strain sensing guage. From equation (2), it can be seen that the original phase of the beat signal is øb °o (5) whenever the term (i%cürI2T), which is much smaller than (w°'r), is neglected. Considering equation (1), the frequency and original phase of the beat signal can be written as (i)0(n -n ) 0b…”