Efficient diode-pumped Er:YAP master-oscillator power-amplifier system for laser power improvement at 2920 nm

Abstract

We report on the first demonstration of laser-diode-pumped master-oscillator power-amplifier (MOPA) system based on Er-doped bulk material working at 2920 nm. The relaxation oscillation at the beginning of the laser pulse from the Er:YAlO3 (YAP) oscillator was suppressed effectively when the pump frequency was increased to 140 Hz, as a result of the establishment of a three-level system. In the amplifier, the small signal gain of the Er:YAP strongly depends on pump duration and repetition frequency, and can reach the upper limit of parasitic oscillation. Further, 25.5 mJ of output pulse energy has been achieved from the amplifier at 150 Hz frequency (2.2 ms pump duration), with over 32% of optical-to-optical efficiency. Further improvement of the amplification ability of the MOPA system was discussed.

Cryogenically cooled 2.8 μm Er:YAP laser with watt-level output power

“…Various methods have been applied to study the power-scaling capacity of 3 μm Er solid-state lasers. 8,10,13,14) Cryogenically cooled lasers are an advanced technique for the development of high-power lasers, 15) given that the thermal properties of laser gain materials exhibit significant improvements at low temperatures. This feature is also attractive for 3 μm Er-doped solid-state lasers because thermal effects (the thermal lensing effect and thermally induced wavefront distortion) and the subsequent material damage are the primary limitations to their power scaling behaviors.…”

“…Significant progress was reported with respect to mid-infrared Er:YAP lasers operating at room temperature. 8,14,18) In 2018, the temperature-dependent spectroscopic properties of a low-doped Er:YAP crystal (1 at% of Er 3+ ) were presented by R. Svejkar et al, and the results revealed higher output powers and slope efficiencies at cryogenic cooling temperatures than at room temperature. 19) However, the Er:YAP used in Ref.…”

“…Therefore, Er-doped bulk lasers based on materials with low phonon energies, e.g., Er:YAP, Er:Y2O3, and Er:Lu2O3, are an alternative approach to the power scaling of 3-µm lasers. Various methods have been applied to study the power-scaling capacity of 3 µm Er solid-state lasers [8,10,13,14].…”

“…The thermal shock resistance of YAP is significantly higher than that of a typical garnet host material such as YAG [8], thus indicating its potential for high-power laser operation. Significant progress was reported with respect to mid-infrared Er:YAP lasers operating at room temperature [8,14,18]. In 2018, the temperature-dependent spectroscopic properties of a low-doped Er:YAP crystal (1 at.% of Er 3+ ) were presented by R. Svejkar et.…”