Transmission property and evanescent wave absorption of cladded multimode fiber tapers

Abstract

Cladded multimode fiber optic tapers are proposed as chemical sensors using evanescent wave absorption. There is no need to strip the cladding; therefore, fabrication is easy and the taper is mechanically stronger than the taper without cladding. The transmission property and evanescent wave absorption are modeled using ray theory and wave theory, respectively. Effects of some parameters on the absorption sensitivity are analyzed numerically. Due to the presence of the cladding, the taper core is not in direct contact with the external medium, leading to some significant differences from the uncladded one, especially when the index of the external medium approaches the index of cladding or core. Tapers are fabricated and absorption experiments are conducted to show the feasibility of such a chemical sensor.

Optimization of Peak Type Metal Clad Waveguide Sensor Using Different Metals

“…Intensive research in the field of optical sensing has resulted in variety of optical sensors like SPR sensor [7]- [8], interferometers [9], resonant mirror sensors [10] and dielectric waveguide sensor [11]. Most of optical sensors are based on evanescent wave sensing [12]- [13]. Itssensing principle is to detect change in refractive index of the waveguide due to change in cover refractive index when evanescent wave interacts with cover medium [14].…”

A Novel Approach to Evaluate the Sensitivities of the Optical Fiber Evanescent Field Sensors

“…To make clear the operation principle of the evanescent field interacting with the analyte and to estimate the sensitivity according to this principle are extremely important to the sensor's designers. This field has attracted a lot of research groups extraordinarily and been widely discussed both based on geometric optics and optical waveguide theory (Yu et al, 2006;Messica et al,1996;Gupta & Singh, 1994;Guo & Albin, 2006). However a big difference between the theoretical and experimental values is often observed especially when the sensor's absorbency is low (Payne & Hale, 1993;Wu et al, 2007;Deng, et al, 2006).…”

Applications of the Planar Fiber Optic Chip

“…The exposed core region serves as an ATR element that can be used for absorbance measurements to detect volatile organic compounds (Blair et al, 1997), probe dye solutions (Ruddy et al, 1990), monitor methane gas (Tai et al, 1987) and ammonium ion (Malins et al, 1998) concentrations, and determine solution pH using indicator doped sol-gel coatings (Gupta & Sharma, 1997;MacCraith, 1993), or an indicator doped polymer film. (Egami et al, 1996) Several investigators have worked to further increase the sensitivity of the de-clad cylindrical core fiber optic sensors by tapering the fiber optic (Guo & Albin, 2003;Gupta et al, 1994;Mackenzie & Payne, 1990;Mignani et al, 1998) or bending the sensing region (i.e. into a U-shape).…”