A 142 W Ho:YAG laser single-end-pumped by a Tm-doped fiber laser at 1931 nm

Abstract

In this paper, a high-power Ho:YAG laser in-band pumped by a Tm-doped fiber laser at 1931 nm is reported. A maximum output power of 142.2 W is achieved at 2091 nm using a single-end-pumped configuration, corresponding to a slope efficiency of 56.7%. This is, to the best of our knowledge, the highest output power directly generated by bulk Ho-oscillators in the 2.1 µm spectral region.

Highly efficient Ho: YAP laser with 202 W of linearly polarized output power at 2118 nm

“…Power and brightness scaling of the Tm, Ho co-doped approaches, however, would be limited by the severe thermal problems induced by the relatively low quantum efficiency, high energy transfer up-conversion (ETU) rate and the energy migrations between the Tm 3+ and Ho 3+ ions [6][7][8]. In-band pumping of Ho 3+ doped solid-state lasers directly to the upper laser level ( 5 I 7 manifold) with 1.9 μm laser diodes [9,10], Tmdoped bulk [11,12] and fiber laser sources (TDFLs) [13,14] has proven to be an attractive approach for power and brightness scaling of ~2.1 μm lasers due to the inherent advantages of the low quantum defect heating (~10%), reduced up-conversion rate and high lasing efficiencies. Moreover, the good beam quality of Tm fiber and bulk pump sources makes it possible that relatively low Ho 3+ concentrations can be used with reduced ETU rates and hence improved energy storage capability in pulsed mode of operation.…”

“…Moreover, the good beam quality of Tm fiber and bulk pump sources makes it possible that relatively low Ho 3+ concentrations can be used with reduced ETU rates and hence improved energy storage capability in pulsed mode of operation. So far, high power and efficient laser operation of Ho 3+ doped diverse gain media, such as YAG, Y 2 O 3 , YLF, LuAG and LuLiF 4 etc., have been demonstrated [12][13][14][15][16][17][18][19]. Up to 142 W and 450 W of continuous-wave (CW) output power at ~2.1 μm have been generated from Ho: YAG oscillator and amplifier with slope efficiencies of 56.7% and 62.5% [12,13].…”

“…So far, high power and efficient laser operation of Ho 3+ doped diverse gain media, such as YAG, Y 2 O 3 , YLF, LuAG and LuLiF 4 etc., have been demonstrated [12][13][14][15][16][17][18][19]. Up to 142 W and 450 W of continuous-wave (CW) output power at ~2.1 μm have been generated from Ho: YAG oscillator and amplifier with slope efficiencies of 56.7% and 62.5% [12,13]. In-band pumping of high optical quality Ho: Y 2 O 3 ceramic has yielded 210.5 W of output power at 2117 nm with a slope efficiency 60.0% [14].…”

50-W average power Ho:YAG SESAM-modelocked thin-disk oscillator at 2.1 µm

“…Among these systems, some remarkable recent achievements include the highest average power of 1060 W from a Tm-based fiber chirped-pulse amplifier (CPA) system at 1.9 µm [8], as well as 123 W from a coherently-combined CPA system with 0.2-mJ pulse energy at 1.94 µm [9]. For Ho-based systems emitting at 2.1 µm, 142-W continuous-wave (cw) lasing has been achieved from a bulk Ho:YAG system [10], and 55 W with 55-mJ and 4.3-ps pulses from a Ho:YLF regenerative CPA [11]. In addition to amplifiers that provide high average power and high energy, significant efforts have been dedicated to developing bulk solid-state oscillators with different hosts.…”

High Power Ho:YAP Laser With 107 W of Output Power at 2117 nm

“…In-band pumping Ho doped materials between 5 I 8 and 5 I 7 levels has minimal thermal loading due to the inherent high quantum efficiency, making it attractive approach to obtain ∼2.1 μm lasers. So far, high power and efficient laser operation of Ho 3+ -doped Ho:YAG [8]- [10], Ho:LuYAG [11], [12], Ho:LuAG [13]- [15], Ho:YLF [16] and Ho:LLF [17] lasers have been successfully demonstrated. Employing four high power Tm:YLF laser pump sources and an oscillator containing two pieces of Ho:YAG in tandem, over 100 W of CW output has been generated with a slope efficiency of ∼68% [9].…”