Filtering characteristic of the microfiber loop resonator embedded in low refractive index polymer

Microfiber loop resonator (MLR) is fabricated by coiling of a microfiber, which was obtained by the stretching of a heated single mode fiber. The MLR is embedded in low refractive index material to keep the system robust. Two comb filters with free spectral ranges (FSRs) of 0.16 nm and 0.71 nm are successfully fabricated with adjustable extinction ratio. The extinction ratio can be adjusted by controlling the state of polarization of the input light. It was also found that the wavelength of each peak and the FSR remain unchanged regardless of the state of polarization of the input light. This MLR does not have major issues with input-output coupling and presents a completely integrated fiberized solution.