Intensity modulated SMF cascaded tapers with a hollow core PCF based microcavity for curvature sensing

Abstract

We propose a highly sensitive curvature sensor based on cascaded single mode fiber (SMF) tapers with a microcavity. The microcavity is created by splicing a small piece of hollow core photonic crystal fiber (HCPCF) at the end of an SMF to obtain a sharp interference pattern. Experimental results show that two SMF tapers enhance the curvature sensitivity of the system and by changing the tapering parameters of the second taper, the curvature sensitivity of the system can be tailored, together with the fringe contrast of the interference pattern. A maximum curvature sensitivity of 10.4 dB/m−1 is observed in the curvature range 0 to 1 m−1 for a second taper diameter of 18 μm. The sensing setup is highly stable and shows very low temperature sensitivity. As the interrogation is intensity based, a low cost optical power meter can be utilized to determine the curvature.

S-shaped microfiber based diaphragm supported optical microphone

“…These reflection spectra are obtained by connecting the third port of the circulator to an optical spectrum analyser. From the graph, it is clear that the fringe contrast (FC) of the reflection spectra gets improved from a value of 4.82 to 14.88 dB when the z value is increased from 0 to 3 mm [33]. The increase in FC can be attributed to the formation of two prominent bends (Bend-1 and Bend-2, as shown in figure 2) which gives the tapered fibre shape of 'S'.…”

“…Variation in the STF's reflection intensity with change in horizontal distance (x) for different values of vertical distance (z) between the two taper ends. central deflection (d) of the diaphragm for a homogeneous pressure (P) is mathematically defined as[33],…”

The Structure and Applications of Fused Tapered Fiber Optic Sensing: A Review

“…Leveraging PCF's temperature-insensitive characteristics, the sensor addressed crosstalk caused by temperature Combining PCF microcavities with tapered optical fibers allows for the exploitation of the microcavity's high-quality factor and optical characteristics, leading to sensors with enhanced sensitivity. Dass et al [67] devised a curvature sensor based on a cascaded single-mode fiber with microcavities and dual-tapered spliced PCF. The dual SMF tapers elevated the system's curvature sensitivity while customizing the curvature sensitivity and interference fringe contrast could be achieved by altering the taper parameters of the second taper.…”

Prospects of Photonic Crystal Fiber as Physical Sensor: An Overview

“…A cladding modes analyzation-based long-period gratings PCF curvature sensor was proposed [94] with sensitivity ~20 nm for 1550 nm wavelength for curvature range 0 to 2 m −1 (Figure 27). A microcavity curvature sensor was manufactured [95] by splicing a hollow core PCF at the end of a SMF. Its maximum sensitivity was found 10.4 dB/m −1 for the curvature range 0 to 1 m −1 with a second taper diameter of 18 μm (Figure 28).…”