Evaluation of amplified spontaneous emission in thin disk lasers using the spectral linewidth

Fluorescence Radiation and Thermal Effect at the Edge of the Disk-Shaped Laser Crystal

“…In this section, the theoretical and numerical model of the edge fluorescence radiation of the thin disk laser is to be established. A pump-probe model [13,15] was used to establish the physical model of the edge fluorescence radiation. In this model, the total fluorescence radiation power radiated to the edge of the pump area of the disk laser can be described as follows:…”

“…When the fluorescence is radiated into the unpumped area, the fluorescence photons will be reabsorbed, especially for the quasi-threelevel crystal such as Yb doped crystal. According to Chen et al [13], nearly all of the fluorescence power was radiated from the edge side. erefore, the total power radiated to the edge of the thin disk crystal can be described as follows:…”

“…In order to simplify the model, the researchers used many methods to theoretically analyze the transmission process and fluorescence characteristics of edge-radiated fluorescence in disk lasers, such as the analytical method [9], semianalytical method [10], finite element analysis method [11], Monte Carlo method [12]. However, since the radiation range of edge-radiated fluorescence covers the entire solid angle of 2π (hemisphere region) [13], it is difficult to measure it directly by conventional methods, and the current research on edge-radiated fluorescence in disk lasers is still at the stage of theoretical analysis. erefore, it is necessary to measure the edge-radiated fluorescence of thin disk lasers quantitatively.…”

“…In order to solve this problem, in 2012, Su and Eggleston investigated the transmission process of fluorescence and amplified spontaneous emission (ASE) photons in the thin disk crystal by using the ray-tracing method and studied the spatial distribution of the fluorescence in the thin disk crystal at different edge conditions [12]. Moreover, to verify the fluorescence intensity at different positions of the thin disk crystal, in 2019, Chen et al established a theoretical analysis of the fluorescence spectra in different areas of the thin disk and measured the spectra of the fluorescence emitted from the pump area and the side of the thin disk crystal through experiments [13].…”

“…Based on Chen's theory [13], in this paper, we studied the transverse transmission of fluorescent photons in the nonpumped area of the thin disk crystal both in simulation and experiment. And then, based on this model, we studied the thermal effect induced by the edge-emitting photon.…”