Study of high power Tm:YLF Innoslab wavelength-selected laser

Abstract

In this study, a laser diode dual-end-pumped Tm:YLF slab laser has been developed. Without using a Fabry-Pérot etalon or a volume Bragg grating, the emission wavelength was selected by different transmissions of the output coupler. The single emission wavelength of 1908.6 nm (1886.4 nm) is selected by the T = 20% (T = 40%) transmission of the output coupler with an FWHM of approximately 1.36 nm (1.10 nm). The corresponding maximum continuous-wave output power of 213 W (173 W) was acquired. The output power stability is about 0.16% (0.23%) in 30 minutes. The optical-to-optical efficiency and slope efficiency are 35.8% (29%) and 43.7% (37.9%), respectively.

315 W, 1.94 μm, Tm:YAP InnoSlab laser

“…Due to the spatial periodic change caused by non-uniform thermal expansion and the refractive index change caused by the thermal dispersion coefficient, some wavelength components of the incident laser deviate from the original condition. The calculated wavelength shift is 1.44 nm when the temperature rises 89 K in [15]. The maximum temperature rise of 38.7 K is simulated in our experiment and the wavelength shift should be 0.626 nm, which is basically consistent with the experimental value of 0.6 nm.…”

“…Although there are many water absorption peaks around 1.94 µm, there is no strong water absorption peak in this region [14]. The main reason for wavelength drift can be explained by quoting [15]. During high-power operation, the laser will produce a thermal effect.…”

202 W dual-end-pumped Tm:YLF laser with a VBG as an output coupler

“…Meanwhile, TEC was also useful, but the effect was not as good as that of microchannel cooler. The wavelength shifted by 1.1 nm from 1907.54 nm at 30 W to 1908.64 nm at 201 W. In addition, the maximum temperature of VBG was 389 K at 201 W. references [17,18] , which consisted of multiple diode laser bars and generated pump lines ( 0.53 mm12 mm [17] , 0.45 mm12 mm [18] ) inside the crystal after passing through the imaging system, we used the 150 W fiber-coupled semiconductor laser respectively dual-end-pumped Tm:YLF slab with a uniform pump spot with a radius of 0.85 mm, which was similar to the oscillating spot, achieving good mode matching.…”

“…Compared with the pump units reported in Refs. [17,18], which consisted of multiple diode laser bars and generated pump lines (0.53 mm × 12 mm [17] , 0.45 mm × 12 mm [18] ) inside the crystal after passing through the imaging system, we used the 150 W fiber-coupled semiconductor laser and dual-end-pumped Tm:YLF slab with a uniform pump spot with a radius of 0.85 mm, which was similar to the oscillating spot, achieving good mode matching.…”

“…x = 520 and M 2 y = 2.1 at only 120 W [18] . Based on the previous reports, the beam quality is very poor in one direction and difficult to control, which has badly limited its application.…”