Tunable Electro-Optical Modulator Based on a Photonic Crystal Fiber Selectively Filled With Liquid Crystal

A liquid-crystal-filled photonic crystal fiber (PCF) is proposed for electro-optical modulation. The E7 liquid crystal is precisely filled in one of the innermost air holes of the PCF and forms an in-fiber optical coupler, and the resonance wavelength can be tuned with a sensitivity of 5.594 nm/Vrms when an external voltage is applied. The device can operate as an electro-optical switch/modulator and exhibits response and recovery times of approximately 47 and 24 ms, respectively from 1414 nm to more than 1700 nm. The proposed structure is expected to have potential applications in electric field sensing and wavelength-tunable electro-optical devices.