| Linear frequency modulation （LFM） technology of laser is a very importanttechnology of Synthetic Aperture Radar （SAL） and FM/CW laser radar system.Solid-state laser of LFM has a rather important applications in the laser radar system.If we want to achieve the LFM, we must ensure that the laser has a output of singlemode at first. The advantage of single mode laser is low noise, good color, and longcoherence length. It has a large field of application. With a stable frequency andnarrow linewidth, the single mode laser is very important in the laser radar system（SAL etc.）. So we must keep the output of laser frequency stable. This is theindemnification of getting LFM. No stability, No LFM.This paper describes the theory of LFM and the laser longitudinal mode, andfocuses on the selectivity of single longitudinal mode—the method of F-P etalon orelectro-optical. And the paper introduces the factors affecting frequency stability andfrequency stabilization measures we take, points that we take specific frequencystabilization measures. We also introduce the spatial hole burning effect, and in ourexperimental program we use the appropriate methods to prevent it. We also introducethe principle of electro-optic modulation method, and in our experimental program towe use the electro-optic crystal RTP. We design the structure of LD-pumpedsolid-state laser LFM, describe the parameters of the entire solid-state system indetail.In the experimental section, we use the Nd:YAG crystal for single mode outputexperiment at first, and give the experimental results obtained for the specific analysis.Another part of the experiment is to use Nd: YVO4crystal for single mode outputexperiment, and we take a series of beam quality measurement for the output. On thisbasis, we conduct a LFM experiment. With using the angle adjustment method andusing the electro-optical adjustment method, we get the frequency tuning range of1.365GHz and1.57GHz, respectively. |
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