Liquid crystal is a viscous chemical whose molecules can be aligned precisely when subjected to an electrical field. Its essential property for use in optical communications is that it can vary the polarization or the phase of light passing through it based on an applied electric voltage. By exploiting this simple property liquid crystal can be used a platform for many powerful optical communication devices that switch, filter and attenuate light. A simple schematic of a liquid crystal processor is illustrated below. Liquid crystal material is embedded between two pieces of glass that is coated with transparent conductive indium tin oxide (ITO) to create the active pixel elements. Electrical leads are terminated on the ITO defined pixels. As minutely narrow beams of light shine through each pixel key parameters such as power level and polarization state can be modified by applying different levels of electric voltage. There are numerous qualities that make liquid crystal the technology of choice for fiberoptic applications: Multi-functional: Liquid crystal can be used to manipulate light in a variety of ways-switching, filtering, attenuating, blocking, polarization shifting and phase shifting-and as such can be used as the basis for a wide variety of dynamic optical modules and components. High Reliability: Liquid crystal material has no moving parts and is intrinsically highly stable. It is a mature technology that is well understood and is already used extensively in military applications that demand high reliability. Transparency: Liquid crystal can be used across all the wavelengths used in optical communications (i.e. C, L, S bands) and introduces virtually no loss to optical signals. The insertion loss of Xtellus liquid crystal optical processors is less than 0.1 dB! Parallel Control: Each pixel corresponding to an individual wavelength can be independently controlled without affecting any other wavelengths. Stability: The state of a pixel and its effect on the wavelength it is processing can be held indefinitely without any complex feedback mechanism. Speed: Liquid crystal can process light on the order of milliseconds which is more than fast enough for network reconfiguration applications. Scalability Liquid crystal can easily scale to handle many hundreds of individually addressable and controllable wavelengths in processors that are only several square centimeters in size. Low Cost: Liquid crystal is inherently a low cost technology. The material cost of a liquid crystal processor used in optical communications devices is about one dollar. Small Form Factor: Liquid crystal processors for optical communications devices are only several square centimeters in size. High Power Handling: Liquid crystal does not absorb any light, it just interacts with it, and so it can handle high optical power without any loss in performance or long term degradation. Low Power Consumption: Liquid crystal requires only milliwatts of power per wavelength controlled. ©   2003   XTELLUS