Temperature sensing with single-mode optical fibres

Interferometric measurement of fiber strain hysteresis and nonlinearity for sensitivity optimization

A simple and reliable fringe-counting method is used to determine the fiber static elastic response in fiber-optic sensors and modulators. Large strain hysteresis and nonlinearity have been observed in the commonly employed configuration of bonding a bare fiber onto a strain element. Jacketed fibers show reduced hysteresis and nonlinearity in their elastic response. Reductions in hysteresis from 23% to 1% of the maximum strain and in the nonlinearity by a factor of 3 have been measured.

All-fiber-optic remote sensing of temperature employing interferometric techniques

An all-fiber interferometric temperature sensor capable of remote operation is described in which the fiber's sensing element is configured as a Fabry-Perot cavity of typically less than 5 mm situated at the end of a lead fiber of arbitrary length (typically 2 m). The sensing element is addressed through a fiber coupler, permitting both remote detection and multiplexing of a number of sensing elements for multiple-point measurements.

Optical fiber calorimeter for measuring CO(2) laser power

A new method of measuring CO(2) laser power by an optical fiber interferometer (calorimeter) is described. The linearity of the phase change vs the irradiated power of the CO(2) laser was observed. The sensitivity was found experimentally to be 0.33 pirad/mW. The response time was almost independent of the CO(2) laser power.