In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier's effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum detectable signal power. The return signals required to attain the SNR threshold are then compared for four cases: direct detection with and without the fiber amplifier and heterodyne detection with and without the fiber amplifier. For the direct detection scheme considered, our results predict a sensitivity increase of 20.6 dB with the addition of the fiber amplifier, yet for heterodyne detection the predicted sensitivity increase is only 3.1 dB.
Copyright © 1993, Society of Photo Optical Instrumentation Engineers
Society of Photo Optical Instrumentation Engineers
acquisition, tracking, pointing, ladar, laser radars, fiber amplifiers, SNR
Salisbury, Michael S.; McManamon, Paul F.; and Duncan, Bradley D., "Sensitivity Improvement of a 1-μm Ladar System Incorporating an Active Optical Fiber Preamplifier" (1993). Electro-Optics and Photonics Faculty Publications. 7.