Wireless enabled multi gas sensor system based on photonic crystals

Slow light in photonic crystal cavity filled with nematic liquid crystal

“…Two different types of photonic crystals were fabricated: one on silicon and other one on InP substrate. Experimentally measured propagating modes observed in the regular air filled photonic crystal waveguide show similar wavelength dependent group velocity that was observed in the simulation [10]. In this present paper we numerically demonstrate tunability of group velocity of photonic crystal filled with liquid crystal.…”

“…Simulation results indicated a lattice constant (a) of 0.445 μm and a hole radius (r) of 0.131 μm will open a TE band gap of 0.25 to 0.31 (a/λ). This corresponds to an allowed wavelength range of 1.39 to 1.75 μm [10]. Figure 2(a) shows the effective refractive indices of ordinary and extraordinary waves.…”

“…These were evaluated as A=1.723, B=0.000524, (∆n) o = 0.3485 and β =0.2542, at 1550 nm. Experimentally found refractive index using bulk E-7 LC from Marc Inc. has been used to do this curve fitting [7][8][9] We designed and fabricate a L3 photonic crystal resonator that has a centre frequency around 1550 nm [10]. 2D and 3D Simulations were carried out using Crystal Wave by Photon Design (http://www.photond.com/) [5, 10].…”

“…Figure 1 shows both schematic and scanning electron micrographs of possible photonic crystal transmission structures with integrated electrodes for liquid crystal tuning. Using an innovative architecture that combines the slow-light of PhC waveguides coupled to PhC cavities [10,[14][15], it is possible to integrated electrodes near such a cavity to tune this local slow-light engineering using the nematic liquid crystals. Figures 1a and 1b show schematic views of possible electrode positions related to the PhC cavity.…”

Photonic Crystals

“…), and metal oxides (SiO 2 , TiO 2 , Al 2 O 3 , WO 3 ). Experiment has shown that PhCs can be applied in practically all types of optical gas sensors, including PhC gas sensors based on spectroscopic absorption (Lambrecht et al 2007 ;Jensen et al 2008 ;Pergande et al 2011 ) , resonance properties (Wang et al 2007 ;Sünner et al 2008 ;Awad et al 2010 ) , surface electromagnetic waves (Colodrero et al 2008 ;Hidalgo et al 2009 ;Hidalgo et al 2010 ) , and self-collimation effects (Wang et al 2008b ) . These sensors can detect a wide range of gases (O 2 , CO 2 , NO 2 , VOCs, N 2 , etc.…”