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Highlights • A microchip Yb:LuPO 4 /WSe 2 passively Q-switched laser is demonstrated. • Sapphire substrate of WSe 2 film is used as an etalon output coupler. • An output power of 1.8 W at 1.2 MHz is generated with pulse duration of 30 ns. Abstract We demonstrate that it is possible for a few-layer WSe 2 /Sapphire to act in specific high-gain solid-state lasers as both saturable absorber for passive Q-switching and as etalon mirror for output coupling. A passively Q-switched Yb:LuPO 4 microchip laser formed in this manner is realized. With 11.5 W of pump power absorbed, a maximum output power of 1.8 W is produced at a pulse repetition rate of 1.2 MHz with a slope efficiency of 25%; the resulting pulse energy, duration, and peak power are, respectively, 1.5 μJ, 30 ns, and 50 W. Our work provides a simple way of making compact, reliable, high-repetition-rate pulsed microchip or miniature solid-state lasers based on 2D saturable absorbers. [ABSTRACT FROM AUTHOR]

Highly efficient high-power laser operation around 1084 nm is demonstrated of the Yb 0 . 14 : Y 0 . 77 Gd 0 . 09 Ca 4 O ( BO 3 ) 3 mixed crystal in a compact plano-concave resonator, producing an output power of 18.1 W in free-running mode, with optical-to-optical and slope efficiencies being, respectively, 60% and 70% with respect to incident pump power. In laser action achieved with the high-gain short-wavelength oscillation being suppressed, the highest output power reaches 16.2 W with an optical-to-optical efficiency of 50.3%, while the slope efficiency amounts to 58%. The results presented reveal the superiority of the Yb-ion doped mixed oxyborate crystal to the existing Yb-ion or Nd-ion crystals capable of generating high-power laser radiation around 1084 nm. [ABSTRACT FROM AUTHOR]

• Q-switching performance of Yb:LaCOB crystal laser is investigated for the first time. • Pulsed radiation in 2-W level is produced in passively Q-switched action with 2D MoTe 2. • Maximum pulse energy of 6.6 μJ is generated. The passive Q-switching performance of an Yb:LaCa 4 O(BO 3) 3 crystal laser was investigated for the first time to our knowledge. Stable repetitively pulsed laser action was demonstrated with a 2D MoTe 2 saturable absorber under high output couplings ranging from 70% up to 95%. A maximum pulsed output power of 2.11 W was produced at a repetition rate of 357 kHz, with a slope efficiency of 32% in terms of incident pump power. The largest pulse energy, minimum pulse duration, and highest peak power achievable were, respectively, 6.6 μJ, 103 ns, and 52.4 W. Our work suggests that this relatively new monoclinic oxyborate crystal may be more advantageous over most of other Yb-ion materials in making high-energy pulsed lasers passively Q-switched with 2D saturable absorbers. [ABSTRACT FROM AUTHOR]

Highlights • Efficient, high-power, passively Q-switched Yb:YCOB/WS 2 laser is demonstrated. • Output power in 4-W level at 0.61 MHz is produced with a slope efficiency of 47%. • Shortest pulse duration of 66 ns is achieved. Abstract We report an efficient high-power Yb:YCa 4 O(BO 3) 3 laser that was passively Q-switched by a few-layer WS 2 saturable absorber. A maximum average output power of 4.05 W was produced at a pulse repetition rate of 606 kHz, with an optical-to-optical efficiency of 40.5% and a slope efficiency of 47%. The resulting pulse energy, duration, and peak power were 6.67 μJ, 66 ns, and 101 W, respectively. Our work demonstrates the great potential of few-layer WS 2 and other 2D transition metal dichalcogenides as saturable absorbers for developing high-power, high-repetition-rate, nanosecond, pulsed solid-state lasers. [ABSTRACT FROM AUTHOR]

Abstract We report on a highly efficient, compact, passively Q-switched Yb:KLu(WO 4) 2 laser, with few-layer MoS 2 or WS 2 acting as saturable absorber. A maximum output power of 2.45 W was generated at a repetition rate of 2.52 MHz, with 6.49 W of pump power absorbed in passively Q-switched operation induced by MoS 2 ; the largest pulse energy, shortest duration, and highest peak power were, respectively, 1.27 μ J, 43 ns, and 29.5 W. With WS 2 as saturable absorber, the output power attainable in stable Q-switched operation was 1.87 W, produced with an optical-to-optical efficiency of 37% and a slope efficiency of 71%. The minimum pulse duration obtained was 39 ns; while the largest pulse energy and highest peak power were 1.19 μ J and 30.5 W. Highlights • Power scaling to 2-W level is demonstrated for Yb:KLuW/MoS 2 (WS 2) laser. • Pulse repetition rates up to 2.5 MHz are reached in stable passively Q-switched action. • Shortest pulse duration of 39 ns is achieved. [ABSTRACT FROM AUTHOR]

An experimental investigation was carried out to study the temperature effects on the laser performance of Yb 3+ :YCa 4 O(BO 3 ) 3 crystal. It was found that the extent, to which the laser performance was affected by temperature rising, was dependent on the lasing wavelength. With the crystal temperature being raised from 1 to 50 °C, the lasing threshold increased by a factor of 1.40–1.82; whereas the rate, at which the output power dropped with rising temperature, was determined to fall in a range from 0.006 to 0.028 W/°C, for laser action producing a moderate output power of 3 W. As the crystal temperature was raised, the laser performance deteriorated in output power, efficiency, and threshold; but the laser beam quality was improved considerably. [ABSTRACT FROM AUTHOR]