Lasing threshold of Nd-doped crystal, ceramic, and glass lasers under spatially inhomogeneous diode pumping

The effect of transverse mode locking on the dependence of the threshold pump power on the cavity length in Nd-doped media lasers with longitudinal inhomogeneous diode pumping is experimentally and theoretically studied in the cavity stability region. An essentially nonmonotonic behavior of the dependence of the threshold pump power on the cavity length is detected. The dependences of the threshold pump power on the cavity length are calculated using the method based on the expansion of the complex field amplitude in Laguerre-Gaussian modes of a cold cavity. The best agreement with calculated results is observed for lasers with Nd:YLF active elements.