EE 566 Optical Communication Ming Li Free Space Optic (FSO)

Why choose this topic? Why still choose this topic?

September 11, 2001, New York

Every thing was destroyed including normal fiber link Every thing was destroyed including normal fiber link Wall street stock market was closed because the communication was destroyed

Two of these units were used between building to re-establish a high speed communication link. Two of these units were used between building to re-establish a high speed communication link. FSO communication between Merrill Lynch Brokerage and Wall Street in New York following the terrorist attack that destroyed normal fiber optic link FSO communication between Merrill Lynch Brokerage and Wall Street in New York following the terrorist attack that destroyed normal fiber optic link

History of Free Space Optics The transmission of information using light is actually not a new idea. The transmission of information using light is actually not a new idea. Great Wall

In the late nineteenth century, Alexander Bell expanded his "phone-phone" communication which modulated by sunlight.

In the mid-1960's NASA initiated experiments to utilize the laser as a means of communication between the ground and space. Gemini-7 Birth of Laser FSO Communications

Space-to-Ground Lasercom Link Space-to-Ground Lasercom Link 2000 km Link Distance 2000 km Link Distance 1 Gbps Transmission Rate 1 Gbps Transmission Rate Satellite Laser Communication

Chinese First Maned Spaceship

Air Force Air Force Its potential for low electromagnetic emanation when transferring sensitive data Its potential for low electromagnetic emanation when transferring sensitive data Navy Navy Secure communication with submerged submarines. Secure communication with submerged submarines. Military Application of FSO

Technology from Space Lasercom

Advantage of FSO Wireless communicate from A to B Wireless communicate from A to B Low costs ($10K to $20K) Low costs ($10K to $20K) High bit rate (10 Mbps to 2.5 Gbps) High bit rate (10 Mbps to 2.5 Gbps) Set up a link in a few days Set up a link in a few days The lasers used are eye safe, so even a butterfly can fly unscathed through a beam The lasers used are eye safe, so even a butterfly can fly unscathed through a beam

Application of FSO Connectivity Solutions Connectivity Solutions 'Last-Mile' Network Solutions 'Last-Mile' Network Solutions Temporary Network Provision Temporary Network Provision Cable Free Connectivity in the Finance Sector Cable Free Connectivity in the Finance Sector CCTV Security Applications CCTV Security Applications GSM Microcell Connectivity GSM Microcell Connectivity

Industrial estates, Science parks and university campus environments typically exhibit a common problem – a number of separate buildings, separated by roads or other obstacles, between which communications links are frequently in demand.

Cable digging, increasingly unpopular in cities, is regulated by the local authority who may restrict re- digging frequency of roads - and the cost may be prohibitive in any case, especially if a river or railway is in the way.

FSO vs RF RF 2.4 GHz systems were typically running at 2-4 Mbps due to interference issues in the unlicensed frequency ranges FSO provided 10 Mbps of throughput for less than unlicensed RF FSO was less cost, more secure, and seemed simpler

Challenge of FSO Challenge #1 — hitting the target Challenge #1 — hitting the target Challenge #2 — interrupted signals Challenge #2 — interrupted signals

Hitting the target Getting a laser beam to hit the mark in a laboratory setting is easy, but in the real world it is much harder. Getting a laser beam to hit the mark in a laboratory setting is easy, but in the real world it is much harder. 1)Atmospheric turbulence 1)Atmospheric turbulence 2)Fog 2)Fog 3)Building movement 3)Building movement

Atmospheric attenuation and scatter 6.5 dB/km150 dB/km225 dB/km 300m distance to tall building

Solution Active beam steering (sometimes involving MEMS), Active beam steering (sometimes involving MEMS), Multiple laser beams, Multiple laser beams, Automated power control, and calculated laser beam divergence. Pulsed laser beams start out just centimeters wide and can diverge to 1 meter or more over typical link distances—like using a really big bullet to hit a small target. Automated power control, and calculated laser beam divergence. Pulsed laser beams start out just centimeters wide and can diverge to 1 meter or more over typical link distances—like using a really big bullet to hit a small target.

Challenge #2— interrupted signals An is beaming across the FSO connection just as a bird flies through, blocking the signal. An is beaming across the FSO connection just as a bird flies through, blocking the signal.

Solution #2—no lost data No fear. FSO linkheads essentially "talk" to one another, and just as people repeat words in conversation, data can be retransmitted in the event of a temporary beam blockage. No fear. FSO linkheads essentially "talk" to one another, and just as people repeat words in conversation, data can be retransmitted in the event of a temporary beam blockage. Several companies even have redundant radio-frequency links that simultaneously transmit the FSO signal. When the radio or the FSO signal is blocked, the counterpart is automatically used—no loss of data, and no delay. Several companies even have redundant radio-frequency links that simultaneously transmit the FSO signal. When the radio or the FSO signal is blocked, the counterpart is automatically used—no loss of data, and no delay.

Companies and rapidly advancing FSO technology AirFiber AirFiber Hybrid Free- space optic/Radio Hybrid Free- space optic/Radio LightPointe LightPointe Multi-beam sending process Multi-beam sending process Terabeam Terabeam carrier-grade FSO equipment and services carrier-grade FSO equipment and services

AirFiber San Diego, California, was founded in AirFiber's products combine FSO with 60 GHz millimeter- wave radio, makes wireless communication possible in any weather. AirFiber's products combine FSO with 60 GHz millimeter- wave radio, makes wireless communication possible in any weather.

LightPointe San Diego, California, was founded LightPointe's FSO products utilize a multi-beam sending process, which overcomes atmospheric degradations and temporary beam obstructions by overlapping redundant infrared beams. LightPointe's FSO products utilize a multi-beam sending process, which overcomes atmospheric degradations and temporary beam obstructions by overlapping redundant infrared beams.

Terabeam Kirkland, Washington, was founded in Terabeam's FSO products have advanced beam-steering features that update beam direction up to 300 times per second. Terabeam's FSO products have advanced beam-steering features that update beam direction up to 300 times per second.

Conlusion FSO is just starting to be applied to solve the Internet “last-mile” interconnectivity problem. Some believe that it may be the unlimited bandwidth solution for the metro urban core of downtown building-to- building communication, as well as the optimal technology for home-to-home and office-to-office connectivity. FSO is just starting to be applied to solve the Internet “last-mile” interconnectivity problem. Some believe that it may be the unlimited bandwidth solution for the metro urban core of downtown building-to- building communication, as well as the optimal technology for home-to-home and office-to-office connectivity.

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