Electrically Sensing Characteristics of the Sagnac Interferometer Embedded With a Liquid Crystal-Infiltrated Photonic Crystal Fiber

Abstract

The electrically sensing characteristics of a liquidcrystal-infiltrated polarization-maintaining photonic crystal fiber have been studied. The small holes on the end face of the fiber collapse and two large holes remain open by controlling dischargingtime, -current and -position of a fiber splicer, then liquid crystal is selectively infiltrated into the two large holes which can not only save liquid crystal, but also make the welding between the liquidcrystal-infiltrated polarization-maintaining photonic crystal fiber and single-mode fiber much easier. A new method to weld the two fibers is proposed by filling and volatilizing ethanol to make liquid crystal a few millimeters away from the end face which can improve the sensing system stability and prevent the discharge of a fiber splicer from destroying LC molecules. A Sagnac interferometer is set up by embedding the liquidcrystal-infiltrated polarization-maintaining photonic crystal fiber in a fiber loop and then its electroresponse characteristics are studied. The refractive-index distribution of the liquid-crystalinfiltrated polarization-maintaining photonic crystal fiber varies with electric voltage due to the variable index of liquid crystal which makes it possible to detect voltage. Three voltage ranges are discussed by the different dips and the sensitivity is improved with voltage increasing. The high sensitivity is up to 3.49 nm/V with the tuning range of 7 nm as voltage changes from 149.67 to 151.61 V. The Sagnac interferometer embedded with a liquidcrystal-infiltrated polarization-maintaining photonic crystal fiber can be utilized as a voltage sensor, electro-optical modulator or filter.

Ultra-Short Polarization Rotator Based on Flat-Shaped Photonic Crystal Fiber Filled with Liquid Crystal

“…Their values are related to temperature, and when the temperature is 25 °C, A o = 1.4994, B o = 0.0070 μm 2 , C o = 0.0004 μm 2 , A e = 1.6933, B e = 0.0078 μm 2 , and C e = 0.0028 μm 2 , respectively. The dielectric tensor of the liquid crystal is [ 21 ]: where ϕ is the rotation angle of the liquid crystal molecules which is modulated by the deflection voltage [ 22 ]: where V c is the threshold voltage and its value is: V c = (π/2R) √(k 11 /Δε); V c is only related to material properties, where the elastic constant k 11 = 34 pF, anisotropic dielectric constant Δε = 10, and R = 1/2 Λ. Λ is the fiber stomatal pitch and its value in this design is 7.8 μm. It can be calculated that V c is 0.743 V.…”

Modeling, decision support, and software for automated positioning of photonic crystal fiber

“…One of the most significant problems is the problem of connecting two PCFs with minimal loss of the useful signal in the connection between them. In connection with that, there is a difficult technical task of determining the necessary mutual position of optical fibers in relation to each other 7 . This work is devoted to solving the problem of minimizing signal losses in connected PCFs 8 by improving the functional complex, information support, mathematical models and methods, algorithms and software used in automated control systems for the connection of optical fibers 9 .…”

Fiber Optic Electric Field Intensity Sensor Based on Liquid Crystal-Filled Photonic Crystal Fiber Incorporated Ring Laser

“…The low relaxation time of LC and higher refractive index (RI) than silicon make it suitable for optical fiber device. Recently, the PCF combined with LC is proposed and all work to date has focused on tuning the PCF band-gap effect completely or partially filled LC [8], [9]. The PCF can be modulated by LC since its pores can be easily filled in capillary effect.…”