All-optical modulation in dye-doped nematic liquid crystal photonic bandgap fibers

Abstract

Photonic crystal fibers (PCFs) have attracted significant attention during the last years and much research has been devoted to develop fiber designs for various applications, hereunder tunable fiber devices. Recently, thermally and electrically tunable PCF devices based on liquid crystals (LCs) have been demonstrated. However, optical tuning of the LC PCF has until now not been demonstrated. Here we demonstrate an all-optical modulator, which utilizes a pulsed 532nm laser to modulate the spectral position of the bandgaps in a photonic crystal fiber infiltrated with a dye-doped nematic liquid crystal. We demonstrate a modulation frequency of 2kHz for a moderate pump power of 2-3mW and describe two pump pulse regimes in which there is an order of magnitude difference between the decay times.

Highdno/dTLiquid Crystals and their Applications in a Thermally Tunable Liquid Crystal Photonic Crystal Fiber

“…In between these two bandgaps, a weaker transmission peak appears. This feature is also a direct consequence of the LC anisotropy, which causes a splitting of the EH 11 mode of an LC-infiltrated microchannel from the HE 12 and HE 31 modes [11,23] so that a narrow bandgap opens up between the cladding states derived from these modes. As observed from Figure 5, the width and transmission of the bandgap is reduced as the temperature of UCF-1 is increased, which is due to a decreasing anisotropy as the temperature approaches the clearing temperature of UCF-1 (T c ¼ 29.7 C), whereby the splitting of the EH 11 , HE 12 , and HE 31 cladding modes is diminished.…”

“…[1][2][3][4]. Besides displays, LCs are also useful for photonic devices such as optical phased array for laser beam steering [5], light switches [6], variable optical attenuator [7], thermal solitons in nematic LCs [8,9], and thermally tunable LC photonic crystal fibers [10][11][12]. For laser beam steering, high birefringence (Dn) and low viscosity LCs are preferred in order to obtain fast response time.…”

Tunable properties of light propagation in photonic liquid crystal fibers

“…no. 1550) manufactured at the Military University of Technology in Warsaw [5,9] was used in our theoretical investigations. The 1550 LC-mixture is composed of alkyl 4-trans-(4-trans-alkylcyclohexyl) cyclohexylcarbonates [5 (Table 2)].…”

“…In this way, we obtain a novel class of active optical fibers that can be called photonic liquid crystal fibers (PLCFs) [1][2][3]. As it was recently demonstrated [1][2][3][4][5], the PLCFs are very promising for a wide range of applications, such as variable optical attenuators, tunable filters, switches, sensors, and other devices applied to sensing and optical transmission systems. True understanding of LCs behaviour and molecular orientation inside very small capillaries is very important for understanding light propagation mechanisms in such structures.…”

Second and Fourth Harmonic Frequencies in Electric Field-Induced Liquid Crystal Reorientations

“…Nematic liquid crystal (LC) has been widely used for amplitude and phase modulations, such as displays [1,2], optical communications [3], adaptive lens [4][5][6][7][8], and tunable photonic devices [9,10]. The applied voltage can be either a square, sinusoidal or saw-tooth wave and the frequency can range from tens to a few kilo-hertz.…”