PRESENTED BY:
Faisal.S

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INTRODUCTION
 Optics has been used in computing for a number of years but the main emphasis has been and continues to be to page link portions of computers, for communications, or more intrinsically in devices that have some optical application or component.
 Optical computing was a hot research area in 1980’s.But the work tapered off due to materials limitations that prevented optochips from getting small enough and cheap enough beyond laboratory curiosities.
 These include optical logic gates, optical switches, optical interconnections and optical memory.
NEED FOR OPTICAL COMPUTING
 The pressing need for optical technology stems from the fact that today’s
computers are limited by the time response of electronic circuits.
 A solid transmission medium limits both the speed and volume of signals, as well as building up heat that damages components.
 The optical computer comes as a solution of miniaturization problem.Optical data processing can perform several operations in parallel much
faster and easier than electrons.
 This parallelism helps in staggering computational power. For example a calculation that takes a conventional electronic computer more than 11 years to complete could be performed by an optical computer in a single hour.
OPTICAL COMPONENT FOR COMPUTING
 VCSEL pronounced ‘vixel’
 There are two special semiconductor materials sandwiching an active layer where all the action takes place.
 But rather than reflective ends, in a VCSEL there are several layers of partially reflective mirrors above and below the active layer.
 Layers of semiconductors with differing compositions create these mirrors, and each mirror reflects a narrow range of wavelengths back in to the cavity in order to cause light emission at just one wavelength.
OPTICAL INTERCONNECTION OF CIRCUIT BOARDS USING VCSEL AND PHOTODIODE
 VCSEL convert the electrical signal to optical signal when the light beams are passed through a pair of lenses and micro mirrors.
 Micro mirrors are used to direct the light beams and this light rays is passed through a polymer waveguide which serves as the path for transmitting data instead of copper wires in electronic computers.

 Then these optical beams are again passed through a pair of lenses and sent to a photodiode.
 This photodiode convert the optical signal back to the electrical signal.
OPTICAL MEMORY
 In optical computing two types of memory are discussed.
One consists of arrays of one-bit-store elements and other is mass storage, which is implemented by optical disks or by holographic storage systems.
 This type of memory promises very high capacity and storage density.
 This research is expected to lead to compact, high capacity, rapid-and random access, and low power and low cost data storage devices necessary for future intelligent spacecraft.
 These devices are used to write data into the optical storage medium at high speed.
 It is rewritable and uses magnetic field modulation on optical material
APPLICATIONS
 High speed communications
 Optical crossbar interconnects are used in asynchronous transfer modes and shared memory multiprocessor systems.
 Process satellite data.