Optically addressed SLM

Rather confusingly, the term spatial light modulator (SLM) is used for two entirely different types of devices, electrically addressed SLMs and optically addressed SLMs. The inference to be drawn from the use... 

Both CdS and a-Si have been successfully used as the photocondoctor 45°-twisted nematic layers and, on an experimental basis, ferroelectric layers have been used for the liquid crystal. CCD structures and silicon vidicon microdiode arrays have been used in place of the photocon-ductive layer. The device is useful both when the write beam is coherent (for example, a scanned laser) and when it is incoherent (for example, a CRT). In the latter case, the SLM can be used as an incoherent-to-coherent converter. The CRT-written device has also found application as a projection display. There exists a very large potential market for optically addressed SLMs in a variety of optical processing applications and for projection displays. 

SLM Spatial light modulator device using either electrical or optical addressing to impress information onto a light beam. 

Previous SLMs have used photoconductors coupled to liquid crystals [237, 238], multiple-quantum-well semiconductors [239] and silver haUde films [240] to exploit such effects as photorefraction [241], photochromism [242, 243] and saturable absorption, etc. The non-linear optical properties of oUgothiophenes make them promising candidates for active photochromic materials in optically-addressed spatial light modulator devices. In particular, speed and spatial resolution can be improved by two orders of magnitude, compared [244] with devices based on liquid crystals or semiconductor heterostructures. 

Considerable effort was placed on the fabrication of custom multi-element lenses and diffractive optics to achieve the fan-out and fan-in. The SLM was a custom made 16x 16 pixel FLC silicon VLSI backplane SLM with a typical contrast of 50 1, filled with a liquid crystal capable of a 15 ps address time. Considerable effort was also... 

Unlike most of the optical devices which we have discussed so far, all-optical SLMs do not need pixelated electrodes and therefore do not have the problems of interconnections and addressing of pixels, which are associated with flat-panel displays. Therefore, SLMs can use very small pixel dimensions, limited by optical... 

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