Directly diode-pumped high-energy Ho:YAG oscillator

; published 0 MONTH 0000 We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Qswitched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a wavelength of 2.09 μm were obtained. The corresponding pulse duration at the highest pump power was 100 ns, leading to a maximum peak power above 300 kW. Different pulse repetition rates and output coupling transmissions of the Ho:YAG resonator were studied. In addition, intracavity laser-induced damage threshold measurements are discussed. © 2012 Optical Society of America OCIS codes: 140.3070, 140.3480, 140.3540, 140.3580. Q-switched high-energy lasers operating in the nominally eye-safe 2 μm wavelength region are vital for applications in medicine, material processing, and lidar systems Regarding coherent light sources in the mid-IR spectral range, Q-switched 2 μm lasers are of great interest because they can be used to pump optical parametric oscillators (OPOs) based on ZGP or periodically poled GaAs [2], which allow for the generation of wavelengths ranging from 3 to 12 μm. Many of these applications call for wavelengths above 2 μm, e.g., ZGP shows a reduced absorption at 2.09 μm compared to 2 μm, leading to a higher conversion efficiency Direct in-band pumping with laser diodes around 1.9 μm is therefore an attractive alternative to develop simple and compact Ho:YAG laser systems with high efficiencies. Barnes et al. published a Q-switched Ho:YAG laser pumped by a pulsed InGaAs laser diode that was wavelength stabilized at 1.86 μm and cooled to 5°C This work demonstrates damage-free high-energy operation of a diode-pumped Ho:YAG laser. For Q-switched operation, a new plano-concave cavity was designed, which is shown i

ID 157763)

We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Qswitched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a wavelength of 2.09 μm were obtained. The corresponding pulse duration at the highest pump power was 100 ns, leading to a maximum peak power above 300 kW. Different pulse repetition rates and output coupling transmissions of the Ho:YAG resonator were studied. In addition, intracavity laser-induced damage threshold measurements are discussed. © 2012 Optical Society of America OCIS codes: 140.3070, 140.3480, 140.3540, 140.3580. Q-switched high-energy lasers operating in the nominally eye-safe 2 μm wavelength region are vital for applications in medicine, material processing, and lidar systems Regarding coherent light sources in the mid-IR spectral range, Q-switched 2 μm lasers are of great interest because they can be used to pump optical parametric oscillators (OPOs) based on ZGP or periodically poled GaAs [2], which allow for the generation of wavelengths ranging from 3 to 12 μm. Many of these applications call for wavelengths above 2 μm, e.g., ZGP shows a reduced absorption at 2.09 μm compared to 2 μm, leading to a higher conversion efficiency Direct in-band pumping with laser diodes around 1.9 μm is therefore an attractive alternative to develop simple and compact Ho:YAG laser systems with high efficiencies. Barnes et al. published a Q-switched Ho:YAG laser pumped by a pulsed InGaAs laser diode that was wavelength stabilized at 1.86 μm and cooled to 5°C This work demonstrates damage-free high-energy operation of a diode-pumped Ho:YAG laser. For Q-switched operation, a new plano-concave cavity was designed, which is shown i

Mid-infrared supercontinuum generation to 12.5μm in large NA chalcogenide step-index fibres pumped at 4.5μm

We present numerical modeling of mid-infrared (MIR) supercontinuum generation (SCG) in dispersion-optimized chalcogenide (CHALC) step-index fibres (SIFs) with exceptionally high numerical aperture (NA) around one, pumped with mode-locked praseodymium-doped (Pr3+) chalcogenide fibre lasers. The 4.5um laser is assumed to have a repetition rate of 4MHz with 50ps long pulses having a peak power of 4.7kW. A thorough fibre design optimisation was conducted using measured material dispersion (As-Se/Ge-As-Se) and measured fibre loss obtained in fabricated fibre of the same materials. The loss was below 2.5dB/m in the 3.3-9.4μm region. Fibres with 8 and 10μm core diameters generated an SC out to 12.5 and 10.7μm in less than 2m of fibre when pumped with 0.75 and 1kW, respectively. Larger core fibres with 20μm core diameters for potential higher power handling generated an SC out to 10.6μm for the highest NA considered but required pumping at 4.7kW as well as up to 3m of fibre to compensate for the lower nonlinearities. The amount of power converted into the 8-10μm band was 7.5 and 8.8mW for the 8 and 10μm fibres, respectively. For the 20μm core fibres up to 46mW was converted. © 2014 Optical Society of America

Compact 2.1 μm Q-switched Ho:YAG laser intra-cavity pumped by a 2 μm OPSDL

Summary form only given. Q-switched lasers operating in the nominally eye-safe 2 μm wavelength region are important for applications such as material processing, medicine, LIDAR systems, and pumping of optical parametric oscillators based on ZnGeP2 or periodically poled GaAs. Many of these benefit from wavelengths above 2.05 μm, which are not accessible by the actually widely used Tm-lasers. The long upper laser level lifetime and large energy storage capacity makes Ho-doped crystals very attractive for these applications. In band pumping of singly doped Ho-crystals around 1950 nm enables high laser efficiencies and reduced heat generation inside the laser crystal due to the low quantum defect. Optically pumped semiconductor disk lasers (OPSDL) based on GaSb could be an attractive and compact pump source. These OPSDL can be pumped with cheap laser diodes around 976 nm or 1470 nm and built up in simple and robust setups. In the wavelength range around 2 μm cw output powers up to 17 W have been demonstrated at room temperature

GaSb-based VECSEL for high-power applications and Ho-pumping

The (AlGaIn)(AsSb) material system has been shown to be ideally suited to realize VECSELs for the 2-3 μm wavelength range. In this report we will present results on increasing the output power of the SDL chips with special emphasis on the 2.8 μm emission wavelength by means of low quantum defect pumping. Further on we have investigated concepts for a VECSEL-pumped Q-switched Ho:YAG laser in order to convert the high cw-power of the VECSEL into pulses with a high peak power. Up to 3.3 mJ of pulse energy were achieved with a compact setup (corresponding to a peak power of 30 kW at 110 ns pulse length) combined with stable pulsing behavior