2. INTRODUCTION:-
What is LASER?
o It is a source of coherent EM waves at infrared & light frequencies.
o Operating range is from 430 to 750 THz.
o Information carrying capacity is immense.
3. WhatisFree-spaceLASER Communication
o Data is transmitted by modulated laser light where the laser beam
travels through the atmosphere.
o It’s a wireless connection through the atmosphere.
o The laser light across the link is at a wavelength of between 780-
920 nm.
o Two parallel beams are used, one for transmission and one for
reception.
5. System overview offree space lasercommunication
o The system consists of two transceivers, each capable of
simultaneously transmitting & receiving either analogue or digital
information.
o User selects between either analogue or digital information via
means of two switches.
o In normal operation, the system is a full duplex analogue/digital
communicator.
8. Freespacemulti-pathlasercommunication systems:
o All laser beams hit the target point(optics & photo-diode of the
receiver)coherently.
o This is achieved by phase control analog circuit.
Advantagesofmulti-path lasercommunication systems:
o Robustness in performance(not all beams are interrupted
simultaneously).
o Better safety.
o Easier design and built of stable laser sources and optics.
9. Hardware:
o It is divided into two main categories:
The analogue transceiver-including VU meter.
The digital transceiver.
o The design incorporates three circuits which perform analogue
modulation, digital modulation, and signal strength display.
o The completed system houses all these modules as a single unit,
sharing the critical input & output components.
10. Advantages:
o Eliminates the need of buried cable installations.
o No need of Govt. licensing.
o No spectrum fees have to be paid.
o No radio interference.
o Systems are quickly deployable.
o High data rate & security.
o More highly directional then RF communication.
o Extremely high bandwidth.
o Large information throughput that is many times greater than RF communication.
o Small antenna size.
o One third in mass.
o Half in power requirement.
11. Securityaspects:
o Due to narrow optical beam paths, they are not accessible unless
viewing directly into the transmitter path.
o Existence of laser beams cannot be detected with spectrum
analyzers.
Safetyaspects:
o Do not require certification for handling or operation.
o Although the emitted laser beam is invisible to the unaided eye, it
can cause eye damage if viewed directly at close range for extended
periods of time.
12. Applications:
o Transmission of digital computer data (LAN interconnect) video,
voice, multiplexed data etc.
o Provides bitrates up to 1.25 Gbps at shorter distances.
o Suitable for temporary connectivity needs such as at conventions,
sporting events, corporate & university campuses, military operations
etc.
13. Conclusion:
o Laser-com technology on path to be operationally fielded in space in
next decade
Revolutionary increases in capability and reductions in size ,weight
& power.
Telecom-like interoperability standards should help keep costs
down.
o Continued R & D to achieve ultimate potential
Laser-com to/from aircraft
Multiple users per terminal(multi-access)
Advanced technology for high sensitivity and high data rates.
