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Open Access A Tm3+ monoclinic double tungstate planar waveguide laser is passively Qswitched (PQS) by a saturable absorber (SA) based on single-walled carbon nanotubes (SWCNTs) randomly oriented in a polymer film. The laser is based on a 18 ¿m-thick 5 at.% Tm:KY1-x-yGdxLuy(WO4)2 active layer grown on an undoped (010)-oriented KY(WO4)2 substrate by liquid phase epitaxy with determined propagation losses 0.7 ± 0.2 dB/cm. The PQS laser generated a maximum average output power of 45.6 mW at 1.8354 ¿m with a slope efficiency of 22.5%. Stable 83-ns-long laser pulses with an energy of 33 nJ were achieved at a repetition rate of 1.39 MHz. The use of SWCNTs as SA is promising for generation of sub-100 ns pulses in such waveguide lasers at ~2 ¿m.

single-layer graphene saturable absorber is employed for passive Q-switching of an Er,Yb:GdAl3(BO3)4 (Er,Yb:GdAB) compact laser, representing the first Er-doped oxoborate laser Q-switched by graphene. This laser ibased on a c-cut 1.8 at.% Er3+, 15 at.% Yb3+:GdAB crystal diode-pumped at 0.976 ¿m. It generates a maximum average output power of 360 mW at 1.55 ¿m with a slope efficiency of 23% (with respect to the incident power). Stable ~1 ¿J / 130 ns pulses are achieved at a repetition rate of 400 kHz. This result represents the shortest pulse duration ever achieved in bulk Er lasers Q-switched by 2D-materials. Graphene is a promising material for generating nanosecond pulses at high repetition rates (MHz-range) in Er-doped oxoborate lasers emitting in the eye-safe range at 1.5-1.7 ¿m.

Monoclinic thulium-doped magnesium monotungstate, Tm3+:MgWO4, is promising for efficient power-scalable continuous-wave (CW) and passively Q-switched lasers at >2 ¿m. Under diode-pumping at 802 nm, a compact CW laser based on Z-cut Tm:MgWO4 generated 3.09 W at 2022-2034 nm with a slope efficiency of 50% which represents the highest output power ever achieved with this type of laser host. Stable passive Q-switching of the Tm:MgWO4 laser is demonstrated for the first time using single-walled carbon nanotubes (SWCNTs), graphene and Cr2+:ZnS saturable absorbers. Using the latter best performance are achieved with 16.1 ¿J / 13.6 ns pulses at 2017.8 nm with to a maximum average output power of 0.87 W and a peak power of 1.18 kW

single-layer graphene saturable absorber is employed for passive Q-switching of an Er,Yb:GdAl3(BO3)4 (Er,Yb:GdAB) compact laser, representing the first Er-doped oxoborate laser Q-switched by graphene. This laser ibased on a c-cut 1.8 at.% Er3+, 15 at.% Yb3+:GdAB crystal diode-pumped at 0.976 ¿m. It generates a maximum average output power of 360 mW at 1.55 ¿m with a slope efficiency of 23% (with respect to the incident power). Stable ~1 ¿J / 130 ns pulses are achieved at a repetition rate of 400 kHz. This result represents the shortest pulse duration ever achieved in bulk Er lasers Q-switched by 2D-materials. Graphene is a promising material for generating nanosecond pulses at high repetition rates (MHz-range) in Er-doped oxoborate lasers emitting in the eye-safe range at 1.5-1.7 ¿m.

Monoclinic thulium-doped magnesium monotungstate, Tm3+:MgWO4, is promising for efficient power-scalable continuous-wave (CW) and passively Q-switched lasers at >2 μm. Under diode pumping at 802 nm, a compact CW laser based on Z-cut Tm:MgWO4 generated 3.09 W at 2022–2034 nm with a slope efficiency of 50% which represents the highest output power ever achieved with this type of laser host. Stable passive Q-switching of the Tm:MgWO4 laser is demonstrated for the first time, to the best of our knowledge, using single-walled carbon nanotubes, graphene, and Cr2+:ZnS saturable absorbers. Using the latter, the best performance is achieved with 16.1 μJ/13.6 ns pulses at 2017.8 nm with a maximum average output power of 0.87 W and a peak power of 1.18 kW.

A diode-pumped Tm,Ho:KLu(WO4)2 microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14 ns / 9 ¿J at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9 ns / 10.4 ¿J / 8.2 kHz pulses were generated at 2061.1 nm corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented predicting the pulse energy and duration. The simulations are in good agreement with the experimental results

We fabricate a few-layer molybdenum disulfide (MoS₂) polymer composite saturable absorber by liquid-phase exfoliation, and use this to passively Q-switch an ytterbium-doped fiber laser, tunable from 1030 to 1070 nm. Self-starting Q-switching generates 2.88 μs pulses at 74 kHz repetition rate, with over 100 nJ pulse energy. We propose a mechanism, based on edge states within the bandgap, responsible for the wideband nonlinear optical absorption exhibited by our few-layer MoS₂ sample, despite operating at photon energies lower than the material bandgap.

Open Access A Tm3+ monoclinic double tungstate planar waveguide laser is passively Qswitched (PQS) by a saturable absorber (SA) based on single-walled carbon nanotubes (SWCNTs) randomly oriented in a polymer film. The laser is based on a 18 ¿m-thick 5 at.% Tm:KY1-x-yGdxLuy(WO4)2 active layer grown on an undoped (010)-oriented KY(WO4)2 substrate by liquid phase epitaxy with determined propagation losses 0.7 ± 0.2 dB/cm. The PQS laser generated a maximum average output power of 45.6 mW at 1.8354 ¿m with a slope efficiency of 22.5%. Stable 83-ns-long laser pulses with an energy of 33 nJ were achieved at a repetition rate of 1.39 MHz. The use of SWCNTs as SA is promising for generation of sub-100 ns pulses in such waveguide lasers at ~2 ¿m.

A diode-pumped Tm,Ho:KLu(WO4)2 microchip laser passively Q-switched with a Cr:ZnS saturable absorber generated an average output power of 131 mW at 2063.6 nm with a slope efficiency of 11% and a Q-switching conversion efficiency of 58%. The pulse characteristics were 14 ns / 9 ¿J at a pulse repetition frequency of 14.5 kHz. With higher modulation depth of the saturable absorber, 9 ns / 10.4 ¿J / 8.2 kHz pulses were generated at 2061.1 nm corresponding to a record peak power extracted from a passively Q-switched Tm,Ho laser of 1.15 kW. A theoretical model is presented predicting the pulse energy and duration. The simulations are in good agreement with the experimental results