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            Spatial Light Modulators

  Spatial Light Modulators (SLM) are fundamental devices for the modification and
  interaction of light with itself and with electronics. There are many different types
  of SLM's, but they can be divided into six major groups:

  • One-dimensional Optical / Optical         (1D O/O)
  • One-Dimensional Optical / Electrical    (1D O/E)
  • One-Dimensional Electrical / Optical    (1D E/O)
  • Two-dimensional Optical / Optical        (2D O/O)
  • Two-Dimensional Optical / Electrical   (2D O/E)
  • Two-Dimensional Electrical / Optical    (2D E/O)

The best known examples of 1D-SLM's are acoustic-optic modulators (1D E/O)
and "SEED" (Self Energized Electro-optical Devices) devices (1D O/O) from the
world of
digital optical computing.

The two dimensional family of devices has over 50 known variants. The most
familiar are the "light valves" found in video projectors (2D E/O). These devices
are just beginning to come into their own in the commercial marketplace,
although they have been known for over a decade. With the exception of the
DMD device and the magneto-optic device, most of the rest of these devices use
a liquid crystal layer as the active electro-optic medium Hudson Research has
been involved in the development of these devices. All of the designs we are
pursuing use solid-state electro-optic crystals as the active layers. This offers a
significant advantage over liquid crystal devices, both in contrast ratio and in
device speed.

Perhaps the most interesting device developed at Hudson Research is the
Variable Electro-Optic Mirror (2D E/O). This device can be implemented as a
mirror, window, beamsplitter, shutter, light modulator, variable wave plate, or
optical logic element. It is a close analog of the transistor in terms of its universal
applicability. It is also one of the few SLM's that can be implemented as either a 1D
or a 2D device. Hudson Research is actively pursuing the formation of a foundry
capability to bring this device into widespread use. In its most basic form, it has
0 to 63% rereflectivity at any given color (frequency), and can be built to achieve
reflectivities of >99.99%. It also has the advantage of scalability in that it can
be manufactured as nanoscale pixelated arrays or large sheets of architectural
glass for "Smart Window" applications.

Another important class of SLM's are the 2D O/O devices. These have a
photocathode as input and produce a polarization modulated beam as output.
The input and output beams have significant isolation (>85dB) and can be at
different frequencies (colors). These are very difficult devices to build and are
not readily available on the commercial market. Hudson Research has built a
number of these devices and will make them available as part of the foundry
product line. They are the fundamental enabling element for all
optical computers,
both digital and analog
.

If you find this interesting and wish to discuss an application or having some of
these devices built, CONTACT US for further information


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