Signal to noise ratio improvement in lidar systems incorporating neodymium doped optical fiber preamplifiers

A continuous-wave-only micron lidar (light detection and ranging) system is modeled to examine the potential benefits of incorporating a neodymium-doped optical fiber amplifier in the path of the returning optical signal. The spectroscopic theory of a four-level dopant is discussed to introduce factors involved in pumping a doped fiber to use as a fiber amplifier. Spontaneous emission effects are considered. Also included is a theoretical analysis of signal-to-noise ratio (SNR) of the lidar system and the effect of the spontaneous emission noise on the SNR. An overview of the experimental design and preliminary experimental results are given.<>