A novel technique of using a 1 x N star fiber optic coupler as a distributed strain sensor in a white-light interferometer to measure the distribution of strain is presented. The measuring principle and 1 x 4 star coupler with four fiber optic strain sensors are demonstrated. The experiment is performed with four sensors attached to a combination plastic specimen.

Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the devel...

Fiber optic probes are a key element for biomedical spectroscopic sensing. We review the use of fiber optic probes for optical spectroscopy, focusing on applications in turbid media, such as tissue. The design of probes for reflectance, polarized reflectance, fluorescence, and Raman spectroscopy is illustrated. We cover universal design principles as well as technologies for beam deflecting and...

Several possibilities for new fiber-optic sensors are proposed that are based on two-photon spectroscopic techniques. Examples are chemical sensors, including multiplexed sensors, as well as magnetidelectric sensors. The development of a compact, low-cost fiber-optic method for tbe accurate measurement of timdfrequency is also proposed.

We report on ABB’s fiber-optic current and voltage transducers and their applications in high-voltage substations. We consider bulk-optics and all-fiber current sensors and voltage sensors that exploit the electro-optic effect in BGO and the piezo-electric effect in quartz.

A directional vibration sensor based on polarization-controlled cladding-to-core recoupling is demonstrated. A compact structure in which a short section of multi-mode fiber (MMF) stub containing a weakly tilted fiber Bragg grating (TFBG) is spliced to another single-mode fiber without any lateral offset. Multiple core modes of the MMF are coupled at the junction and appear as well defined reso...

Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some s...

Optically driven recirculating delay lines, often used in fiber-optic signal processors, convert the source phase noise to spectrally structured intensity noise at the loop output. This spectrum is characterized by deep notches at zero frequency as well as at other multiples of l/(loop delay). An expression is derived for the power spectral density of the output noise. The formulae obtained, ar...

BACKGROUND This crossover study compared fiber-optic assessment of laryngeal mask airway (LMA) position in children using two LMA insertion techniques, i.e., standard and rotational. METHODS Seventy-eight ASA I children, aged 2.5 months to 10 years, undergoing elective cataract surgery were included in this study. LMA was inserted in random order using either standard or rotational technique,...

We propose two techniques to suppress intrinsic sidelobe spectra in all-fiber acousto-optic tunable filter using torsional acoustic wave. The techniques are based on either double-pass filter configuration or axial tailoring of mode coupling strength along an acousto-optic interaction region in a highly birefringent optical fiber. The sidelobe peak in the filter spectrum is experimentally suppr...