Birefringence voltage controlled

As a consequence of the voltage-controlled destructive interference, the applied electrical signal is transduced onto the optical beam as an amplitude modulation. The birefringent modulator depicted in Eig. 3.11b functions as an electri-cal-to-optical signal transducer. Here, both TM and TE optical modes traverse... 

We discuss the splay-bend distortion induced by an electric voltage applied to a cell similar to that shown in Fig. 11.16 using two transparent electrodes at z = 0 and z = d. The distortion is easy to observe optically for the cell birefringence. The splay-bend cell behaves like a birefringent plate discussed in Section 11.1.1 but now the plate birefringence is controlled by the field. The optical anisotropy... 

If the material has a positive dielectric anisotropy, then an electric field can convert the twisted structure to one that eventually has the optical properties of a perpendicularly oriented one. A threshold voltage, as shown in Fig. 7, is present only at sufficiently high voltages is the difference between the still-twisted and the non-twisted structure undetectable. As in the voltage-controlled birefringence, the tilt of the... 

TF Systems A TF is a device whose spectral transmission can be controlled by applying a voltage or acoustic signal. There are two main TF devices acousto-optical TF (AOTF), based on diffraction, and liquid crystal TF (LCTF), based on birefringence. An AOTF is a transparent crystal in which an ultrasonic wave field is created,... 

Fig. 33. Diffraction efficiency versus voltages for spatial frequencies in mm-1 10 (/), 28 (2), 51 (i). Switch on time versus voltages at spatial frequencies in mm"110 (/ ), 36 (2 ), 60 (S ). Commutational regime for polyimide-liquid crystal modulator with controlled birefringence [256]...

The birefringence of the liquid crystals is controlled electronically. Either ferroelectric or nematic liquid crystals are used for the tunable retarders. By varying the input voltage to the liquid crystals the birefringence of that material can be changed to vary the retardation and change the interference pattern in such a way as to scan the spectral region of interest. 

When a voltage U > is applied, the sample is deformed. The retardation between the wavefronts of the ordinary and the extraordinary rays of transmitted light is dependent on the applied voltage. The effect is called DAP-effect (Deformation of Aligned Phases) or electrically controlled birefringence and can be applied in display devices [52—55] (see third part of this book). 

To exploit the electric field-induced birefringence in display applications, the polarization of the incident light through the optical retardation produced by the induced birefringence is simply controlled in a manner similar to the mode of retardation control used for in-plane switching (IPS). If a simple comb-shaped IPS electrode is used for the device, the optical axis of the induced birefringence is parallel to the electric field, and the optical axes lie mainly in a plane perpendicular to the comb [21, 22]. A typical voltage-transmittance curve is shown in Fig. 8.18. 

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