An optical computer uses light instead of electricity for computation. It has two types - hybrid, which uses both light and electricity, and pure optical, which uses only light. Optical computers are needed because transistors can no longer keep up with Moore's Law. They use components like lasers, fiber optics, and holographic memory to transmit and store information as light pulses. Optical computing provides benefits like vastly increased speed and bandwidth compared to traditional electronics. Potential applications include high-speed communications and database searches.

1. A G M Rural College of Engineering and Technology
Navagrah Teerth, Varur.
OPTICAL COMPUTER TECHNOLOGY
Under the Guidance of
Mrs.SNEHA B.E, M.Tech.
Asst. Professor
Submitted by
Preeti.K.S

2. CONTENTS
 Why we need them?
 What is optical computer?
 Block diagram
 Optical transistors
 Key components of optical computing
 Merits
 Applications

3. Why We Need Them ?
 Moore’s Law states that the number of transistors on a
computer chip doubles every eighteen months.
Traditional transistors can no longer keep up.
 „Too many transistors will slow down processor
speeds. „Transistors have physical size limits.
 Metallic wires limit the speed of transmission.
 Resistance per unit length in the chip is being increased,
causing more power usage and excess

4. What Is an Optical Computer?
 An optical computer is a computer that performs its
computation with photons as opposed to the more
traditional electron-based computation.
 There are two different types of optical computers
1. Electro optical hybrid computers
2. pure optical computers

5. Electro-Optical Hybrid computers
 Use optical fibers and electric parts to read and direct
data from the processor
 Light pulses send information instead of voltage
packets.
 Processors change from binary code to light pulses
using lasers.
 Information is then detected and decoded electronically
back into binary.

6. Pure Optical Computers
 Use multiple frequencies
 Information is sent throughout computer as light waves
and packets.
 No electron based systems
 No converstion from binary to optical necessary, greatly
increasing the speed.

7. Optical Computer

8. Information flow in optical computers
 Information gets sent in from keyboard, mouse, or other
external sources and goes to the processor.
 Processor then sends the information through logic gates
and switches to be programmed.
 The information is then sent through different fiber optic
cables depending on it’s final location.

9.  Some information will be sent to the holographic
memory, where it will then be saved.
 After information is saved and the program would like
to use it,the program sends a command to the processor,
which then sends a command to receive the information.
 The program receives the information and sends a signal
back to the processor to tell it that the task is complete.

10. Optical Transistors
 Transistors based off of the Fabry-Perot Interferometer. „
1. Constructive interference yields a high intensity (a 1 in
binary) „
2. Destructive interference yields an intensity close to
zero (a 0 in binary)

11. Constructive Transistor

12. Destructive Transistor

13. SOME KEY OPTICAL COMPONENTS FOR
COMPUTING
 VCSEL (VERTICAL CAVITY SURFACE EMITTING
LASER)
 SLM (SPATIAL LIGHT MODULATORS)
 SMART PIXEL TECHNOLOGY
 WDM (WAVELENGTH DIVISION MULTIPLEXING)

14. VCSEL (VERTICAL CAVITY SURFACE
EMITTING LASER)
 VCSEL is a specialised laser diode
that is mainly used for fiber optic
communication by improving
efficiency and increase in data
transfer rate
 The VCSEL emits a narrow, more
nearly circular beam than
traditional edge emitters; this
makes it easier to get the energy
from the device into an optical
fiber.

15.  The VCSEL emits its coherent
energy perpendicular to the
boundaries between the layers.
 The VCSEL is cheaper to
manufacture in quantity, is easier
to test, and is more efficient.
 The VCSEL requires less electrical
current to produce a given
coherent energy output.

16. SLM (SPATIAL LIGHT MODULATORS)
 A spatial light
modulator (SLM) is an object
that imposes some form of
spatially varying modulation on
a beam of light.
 SLMs are used extensively
in holographic data
storage setups to encode
information into a laser beam

17. SMART PIXEL TECHNOLOGY
 Smart pixel technology is a relatively new approach to
integrating electronic circuitry and optoelectronic devices in a
common framework.
 Here, the electronic circuitry provides complex functionality
and programmability while the optoelectronic devices provide
high-speed switching and compatibility with existing optical
media.
 Application of one specific smart pixel technology to a 2D
application of analog-to-digital conversion called digital image
halftoning.

18. WDM (WAVELENGTH DIVISION MULTIPLEXING)

19.  It is a analog multiplexing technique used to combine
optical signal.

20.  Wavelength division multiplexing is a method of
sending many different wavelengths down the same
optical fiber.
 . Using this technology, modern networks in which
individual lasers can transmit at 10 gigabits per second
through the same fiber at the same time.
 WDM can transmit up to 32 wavelengths through a
single fiber, but cannot meet the bandwidth
requirements of the present day communication
systems.

21. DWDM(Dense wavelength division multiplexing)
 Dense Wavelength Division Multiplexing (DWDM) is an
optical multiplexing technology used to increase bandwidth
over existing fiber networks.
 This can transmit up to 1000 wavelengths through a single
fiber.
That is by using this we can improve the bandwidth
efficiency.

23. Construction and reconstruction of information

24. HOLOGRAPHIC MEMORY
 A holographic memory can store data in the form of a
hologram within a crystal. A laser is split into a
reference beam and a signal beam. Signal beam goes
through the logic gate and receives information The two
beams then meet up again and interference pattern
creates a hologram in the crystal.
 It is a data storage system which stores information at
high density inside the system

25. RECORDING DATA

27. MERITS
1.Optical computing is at least 1000 to 100000 times faster
than today’s silicon machines.
2. No short circuits, light beam can cross each other without
interfering with each other’s data
3. Light beams can travel in parallel and no limit to number of
packets that can travel in the photonic circuits.
4. Optical computer removes the bottleneck in the present day
communication system

28. ADVANTAGE OVER TRADITIONAL
ADVANTAGE OVER TRADITIONAL
INTERCONNECTIONS

29. APPLICATIONS
 High speed communications :The rapid growth of
internet,expanding at almost15% per month, demands faster
speeds and larger bandwidth than electronic circuits can
provide.
 Super fast searches through databases.
 Optical Computing In VLSI Technology :optics may provide
drastically new architectures to overcome some conventional
electrical architectural problems of conventional electrical
computers.