A transflective nano-wire grid polarizer is fabricated on a single mode fiber tip by focused ion beam machining. In contrast to conventional absorptive in-line polarizers, the wire grids reflect TE-mode, while transmitting TM-mode light so that no light power is discarded. A reflection contrast of 13.7 dB and a transmission contrast of 4.9 dB are achieved in the 1,550 nm telecom band using a 20...

A novel fiber-optic sensor assembly for continuous monitoring of moisture over extended subsurface environments, such as road embankments, wall backfills, and landfills is presented. This sensor meets the requirements of subsurface monitoring by distributed measurements over linear positioning of a single fiber. The sensor assembly is composed of a communication optical fiber and a hydrophilic ...

We present a fiber-optic Fizeau interferometric strain sensor consisting of an in-fiber spherical microcavity of 39um in diameter. The spherical microcavity was formed by splicing a normal single-mode fiber with a hollow-core photonic crystal fiber. We demonstrate that strain sensing can be realized by using the interference between the light signals reflected by the front and rear surfaces of ...

A novel intrinsic fiber optic pressure sensor realized with a polarization-maintaining photonic crystal fiber (PM-PCF) based Sagnac interferometer is proposed and demonstrated experimentally. A large wavelength-pressure coefficient of 3.42 nm/MPa was measured using a 58.4 cm long PM-PCF as the sensing element. Owing to the inherently low bending loss and thermal dependence of the PM-PCF, the pr...

In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the tran...

In the present study, a surface plasmon resonance (SPR) based fiber optic sensor is proposed. The extreme sensitivity of SPR modes on the surrounding refractive index has been exploited to make the sensor. The optical fiber is coated with gold film which supports the propagation of surface plasmons. The SPR dip in the transmission spectrum is observed and its shift with varying refractive indic...

This research established the design guidelines for center embossed diaphragms for micro-diaphragm fiber type sensors. Following the guidelines, a center embossed diaphragm fiber optic sensor (CE-DFOS) based on Fabry–Perot interference was designed and fabricated with micro-electro-mechanical system (MEMS) technology. The CE-DFOS was experimentally verified to have the designed intrinsic freque...

Photonic sensors, signal processors and communication technologies have emerged as viable alternatives to electronics. Fiber optic sensors which can readily be integrated with smart materials and structures offer an immense potential in the realization of intelligent systems. This paper presents an overview of different types of fiber optic sensors and their application to smart structures.

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