Tunable Electro-Optical and Thermal Optical Modulator Based on a Liquid Crystal-Filled Side Hole Fiber in Fiber Ring Laser

A new tunable electro-optical and thermal-optical modulator based on a liquid crystal (LC) filled side hole fiber (SHF) in fiber ring laser (FRL) system has been proposed and experimentally demonstrated. The LC is penetrated into the air hole of SHF, and the refractive index (RI) of LC will be altered when an external electrical field or temperature difference is applied due to thermal-optical effects and electro-optic effects. SHF is used as both a filter and a sensing head in the laser cavity. Besides, the resonance wavelength is more sensitive to the temperature variations due to high thermal-optic coefficient when incident light interacts with the internal infiltrated LC. Meanwhile, the sensor has good performance with a high extinction ratio (>42 dB) and a narrow 3-dB bandwidth (less than 0.08 nm). The consequent thermal and electronic sensitivity are measured to be −4.23 nm/°C and 0.604nm/V, respectively. Moreover, the excellent and reliable performance expected to monitor the temperature and electric field as the wavelength-tunable electro-optical devices within a small temperature change range is needed.