Two-Parameter Elliptical Fitting Method for Short-Cavity Fiber Fabry–Perot Sensor Interrogation

Abstract

To solve the cavity interrogation problem of short cavity fiber Fabry–Perot sensors in white light spectral interrogation with amplified spontaneous emissions (ASEs) as the white light sources, a data processing method, using an improved elliptical fitting equation with only two undetermined coefficients, is proposed. Based on the method, the cavity length of a fiber Fabry–Perot sensor without a complete reflection spectrum period in the frequency domain can be interrogated with relatively high resolution. Extrinsic fiber Fabry–Perot air-gap sensors with cavity lengths less than 30 μm are used to experimentally verify the method, and are successfully interrogated with an accuracy better than 0.55%.

Experimental Investigation of optical fiber Fabry-Perot resonators: resonance enhancement through reflective coatings and concave mirrors

“…Fabry-Perot (F-P) resonator is one of the most popular type of optical resonators, which found numerous applications in various optical instruments, including laser cavities, spectrometers and sensors. Since the traditional free-space F-P resonators has been extensively studied and characterized through last decades [1], [2], [3], the developed theory behind them does not accurately apply to now emerging optical-fiber-based F-P resonators [4], [5], [6], [7]. The fact that the beam emitted from an optical fiber experiences divergence and that the light after each roundtrip needs to meet the condition of the acceptance cone of the fiber, makes the operation of optical fiber F-P resonator distinct from the operation of standard F-P [8].…”