Light sensor based on carbon tetrachloride-infiltrated side-hole fiber.

We propose a high-sensitivity light sensor based on side-hole optical fiber filled with carbon tetrachloride. Using a fusion splicer, we employed a selective glue coating method to fill one of the air holes with liquid. Coupling occurs between the propagation modes of the liquid waveguide filled with carbon tetrachloride and the core propagation modes, resulting in resonant dips in the transmission spectrum. When the temperature changes, the refractive index of carbon tetrachloride changes, affecting the coupling and causing the wavelength of resonant dips to shift. In this experiment, the temperature sensitivity of the sensor was tested and reached up to 46 nm/°C. Utilizing its high-temperature sensitivity, the infrared laser light intensity was measured with a sensitivity of 0.114 nm/(mW/cm²). While maintaining a high level of sensitivity, the sensor is also easy to fabricate and cost-effective. Therefore, it holds great potential for applications requiring high-precision laser power measurement, laser manipulation, optical modulation, and optical switching.