ABSTRACT
Dynamic surface force measurements of the response of a smectic A to layer normal stress exhibited time dependence for topological events in which single smectic layers were added or removed. Single layer-sized jumps in sample thickness had a rapid component of duration of approximately 1 second that produced most of the change in separation, but that was heralded by a slow precursor acceleration in separation, which began up to a few hundred seconds before. This avalanche-like dynamic signature is consistent with a relaxation mechanism based on the Glaberson-Clem-Bourdon instability of vortex lines (screw dislocations) in the smectic order parameter.
ABSTRACT
Advanced spatial light modulators both detect incident light and modulate reflected light. Each pixel may contain multiple photodetectors, a modulator, control circuitry, and signal-processing circuitry. Because each detector and modulator occupies only a fraction of the area of a pixel the optical efficiency of these devices suffers. We have experimented with improving optical input/output performance by integrating a microlens array with a ferroelectric liquid-crystal VLSI spatial light modulator. We have studied the microlens VLSI spacing accuracy that must be achieved to yield minimum distortion of ref lected wave fronts and the best optical efficiency for Fourier-transform applications.
ABSTRACT
The spatial light modulator based on total internal reflection at the ferroelectric liquid-crystal-glass interface has a 10(7):1 contrast ratio, a 250-micros response time, and a lambda/8 transmitted wave-front uniformity. These properties make the spatial light modulator well suited to provide frequency-band excision in acousto-optic spectrum analyzers.
ABSTRACT
Surface-stabilized ferroelectric liquid crystals (FLC's) are promising materials for semiconductor integrated-circuit-based spatial light modulators. For coherent optical processing applications, phase stability upon repeated switching is critically important. The phase characteristics of an FLC device were measured at switching rates of up to 1 kHz and found to be very stable. The change in the total optical path length through the cell was found to be < 0.0025λ at a wavelength of 632.8 nm. The static optical characteristics were measured for a range of temperatures at and above room temperature in order to be able to identify any temperature-induced phase changes upon switching. The temperature of the FLC cell was externally varied, and changes in the birefringent optical path difference, the optical path length, and the optic axis tilt angle were measured. However, because of the observed phase stability of the FLC, the change of temperature caused by switching was determined to be < 0.046°C. It is clearly shown that FLC's can exhibit the stability needed for critical coherent and incoherent optical data-processing applications.
ABSTRACT
Electro-optic modulators using ferroelectric liquid-crystal technology have generally been limited to use with polarized light. It is possible, however, to construct a diffractive array of ferroelectric liquid-crystal phase modulators that can act as a shutter for unpolarized light. We have built two types of polarization-independent diffractive shutter based on this principle. We describe their principles of operation and performance.
ABSTRACT
We present the design and characterization of a spatial light modulator (SLM) comprising a ferroelectric-liquid-crystal light-modulating layer on top of a silicon integrated circuit. Our SLM consists of two electrically addressed arrays on the same integrated-circuit die. The first, a 1 x 128 linear array with a 20-microm center-to-center element spacing, used shift register addressing, while the second, a 64 x 64 square array with 60-microm pitch, used static random access memory addressing. The resulting SLM could be addressed at frame rates of up to 4.5 kHz and gave singleelement intensity contrast ratios of 12:1.
ABSTRACT
Optical phase conjungation using an amorphous silicon/ferroelectric-liquid-crystal light modulator shows an optical response of 100 microsec with a diffraction efficiency of 8.5% for an incident optical intensity of 1 mW/cm(2).
ABSTRACT
We describe parallel optical XOR and XNOR logic gates implemented with ferroelectric liquid-crystal (FLC) electro-optic elements to yield naturally a logic in which the binary gate outputs are indicated by two orthogonal polarizations of transmitted light. These gates absorb no power from the incident light beam and hence can be cascaded without the need to regenerate NOT inputs. The FLC elements also confer the advantages of low-voltage, low-power, submicrosecond switching and intrinsic two-state memory. Experimental results demonstrating the XOR and XNOR function are presented, along with measurements of the percentage of polarized light rotated into the two binary states.
