Spectral longitudinal mode character of short coherence solid laser for interferometry

Spectral longitudinal mode character of short coherence solid laser is analyzed with complex coherence degree. The relation between optical path difference and complex coherence degree with multi-longitudinal modes is deduced. Comparing narrow line width laser and normal wider line solid laser in simulation, the complex coherence degree of solid laser decreases more quickly with wider line width and more longitudinal modes. An experimental short coherence solid laser for interferometry is built. The coherence length is measured. The result is in agreement with the foregoing analysis.