[attachment=2502]

Free Space Laser Communications


Introduction
¢ Free space laser communications
“ a.k.a. Free Space Optics, Optical

---

Presented By

Phillip Dykstra
WareOnEarth Communications Inc.

---

Wireless
¢ Basically a laser and a telescope
¢ Most are protocol independent
¢ Typical range < 4 km (.5, 1, 2, 4,

8km)
¢ Typical bandwidths: 10, 100, 1000

Mbps
“ Lucent 10 Gbps DWDM (TeraBeam)

Transmitters
¢ LED (single or multiple)
“ 1 mW typical
¢ Laser (single or multiple)
“ 10-20 mW typical, up to 100 mW
¢ Usually 785 or 850 nm, some 1310

nm
¢ Eye safety limit: 1.5 mW/cm^2 at

785 nm
¢ Multiple transmitters boost power,

may also reduce scintillation fades

Detectors
¢ PIN Diodes
-43 dBm typical
¢ Avalanche Photo Diodes (APD)
-53 dBm typical (also greater dynamic

range)
¢ Single or multiple detectors
¢ Larger aperture increases receive

power, reduces scintillation fades
¢ Design goal: BER < 10^-9 typical