Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. Trans-cis conformational change of the azo-dyes under light irradiation. (a) Equivalent energy diagram: under light illumination molecules undergo a fast transition to the excited state and a fast decay to the cis state, then, thermal relaxation brings them back to the trans state; Γ is the associated slow decay rate. (b) Molecules representation: in the trans state molecules are aligned along their long axis while in the cis state they are characterized by a V-like shape. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. Storage of the light pulse: the blue line is the input signal pulse, the red line is the output pulse which is recovered after switching off the pump (dashed line); the off time is increased from bottom to top. In the inset, a magnification of the output pulse retrieved after 160 ms is shown. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. The liquid crystal light-valve, LCLV, and its optical response. (a) Schematic representation of the LCLV: BSO is the photoconductive wall, V0 the applied voltage, LC the liquid crystal layer, ITO the transparent conductive layers; a laser beam of amplitude E passing through the LCLV acquires a phase retardation Δφ. (b) The measured phase retardation Δφ is plotted as a function of the input light intensity I=|E|2. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. Slow light in the LCLV. (a) Experimental scheme of the two-beam coupling experiment. (b) Measured time dependency of the output pulse (red line, I−2) taken on the m=−2 diffraction order of the input pulse (black line, Iin). Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Time dependencies of the input and output pulse for an input pulse width t0=170.7 ms; the output pulse delay is 20 ms. (b) Output group delay Δt as as a function of the input pulse width t0. The dashed line is a guide for the eyes. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Spectral position of the pump beam with respect to the chiral reflective band and MR absorption spectrum. (b) Experimental scheme for the two-beam coupling experiment; CLC is the chiral liquid crystal cell, h→ is the helical pitch direction; a photodiode, PD, measures the output pulse on the m=−2 order diffracted beam. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Setup for the detection of phase modulations in a speckle field; PZT is a piezoelectric transducer in contact with the multimode MM fiber. (b) Signal Vphotodiode detected as a function of time for a 5 KHz driving of the PZT. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Calculated fraction NC/N of molecules in the cis state versus the frequency detuning Δω. The parameters used in the calculation are ΦTC=0.25, ΦCT=0.4, Γ=5.29 s−1, σT/σC=7. (b) Corresponding transparency window produced by two-beam coupling in the dye-doped chiral liquid crystal medium. Lines are theoretical curves; squares are experimental data. (c) Associated phase variation around Δω=0. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. Enhancement of the effective optical path length. (a) Schematic representation showing a LC slow light medium of thickness 15 μm inserted in an optical path of 1-m physical length. (b) Equivalent optical path length calculated for a propagation distance of L=1 m and plotted on log-log scale as a function of the pulse spectral width Δω. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. Resonant coupling in the LCLV. (a) Gain G0 and (b) phase shift Φ0 for the first-order output beam as a function of the frequency detuning Δω between the pump and signal; β=80. Lines are theoretical curves; dots are experimental data. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE

Date of download: 6/30/2016 Copyright © 2016 SPIE. All rights reserved. (a) Schematic principle setup of a polarization interferometer with slow light enhanced birefringence: LC liquid crystal medium, PBS polarizing beam-splitter, P1 and P2 polarizers, PZT piezoelectrically driven mirror, A analyzer, PD photodiode. (b) Sensitivity of the interferometer: output intensity IoutP vs Δν; solid line: theoretical curve, black squares: experimental points. Figure Legend: From: Slow light in liquid crystal media Opt. Eng. 2014;53(10): doi: /1.OE