Refractometers and tunable components based on side-polished fibers with multimode overlay waveguides: role of the superstrate

Abstract

A normal mode analysis is applied to the investigation of the role of the superstrate in terms of its refractive index and thickness in estimating the performance of fiber refractometers and the tunability of fiber components based on evanescent coupling of a side-polished fiber to a multimode overlay waveguide. The model is shown to yield a complete transfer function and information about all the major characteristics of such in-line fiber devices. The results closely match the trends of the reported experiments.

High Sensitive Fiber Optic Temperature Sensor Based on a Side-polished Single-mode Fiber Coupled to a Tapered Multimode Overlay Waveguide

“…The evanescent field coupling between a SPF and an appropriate multimode overlay waveguide (MMOW) has yielded an important platform to realize various fiber optic sensors such as refractive index, pH and temperature sensors [6][7][8][9][10][11][12]. Such a composite structure essentially functions as an asymmetric directional coupler with a band-stop characteristic attributable to the wavelengthdependent resonant coupling between the guided mode of the SPF and one or more modes of the MMOW.…”

“…Such a composite structure essentially functions as an asymmetric directional coupler with a band-stop characteristic attributable to the wavelengthdependent resonant coupling between the guided mode of the SPF and one or more modes of the MMOW. The throughput power of the SPF exhibits dip(s) at the phasematching (or resonant) wavelength(s) [5,6]. Since the refractive index (n0) of the film of the MMOW depends on temperature, any change in n0 would modify the mode spectrum of the MMOW and hence the throughput power spectrum of the device, which shifts the resonance wavelength.…”

Design and realization of a side-polished single-mode fiber optic high-sensitive temperature sensor

“…Side polished fiber technology based on evanescent field coupling between a SPFHC block and a MMOW on its top is proven to be a versatile platform for realizing variety of all-fiber optical components/ devices like directional couplers, switches, modulators, mode splitters, polarizers, wavelength filters, EDFA gain flattening filters, etc [1][2][3][4][5][6]. The same technology platform could be exploited to configure a host of fiber optic sensors like refractometer and biosensors [7][8][9][10][11][12][13]. Underlying physical principle of these sensors involves tracking the measurand-induced shift in the phase resonance wavelength (λ r ), at which maximum power coupling takes place between the SPFHC and the MMOW.…”

Wideband tunable fiber short-pass filter based on side-polished fiber with dispersive polymer overlay

“…The film is thick enough to prevent resonance ref lections from the superstrate when n o $ n eff . 1,7 An optical spectrum analyzer (OSA) was used to record the spectral responses of the SPFs for various index liquid overlays.…”