Ja. Overbeck et al., REQUIRED ENERGY FOR A LASER-RADAR SYSTEM INCORPORATING A FIBER AMPLIFIER OR AN AVALANCHE PHOTODIODE, Applied optics, 34(33), 1995, pp. 7724-7730
The transmitted energy required for an airborne laser radar system to
be able to image a target at 20 km is investigated. Because direct det
ection is being considered, two methods of enhancing the received sign
al are discussed: (1) using an avalanche photodiode (APD) as the detec
tor and (2) using a commercial fiber amplifier as a preamplifier befor
e a photodetector. For this analysis a specified signal-to-noise ratio
was used in conjunction with the radar range equation, which includes
the effects of atmospheric transmission and turbulence. Theoretical a
nalysis reveals that a system with a fiber amplifier performs nearly t
he same as a system incorporating an APD.