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We demonstrated a narrow pulse-width long-wave infrared ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumped by a 2.1 μm Ho:YAG master oscillator power-amplifier (MOPA). By short-cavity structure, a minimum pulse width of ∼12 ns was achieved at 1kHz, 2kHz and 3kHz in Ho:YAG oscillator. By employing a three-stage amplifier, a maximum average output power of 73.1 W with pulse width of ∼17 ns at the pulse repetition frequency of 3 kHz was obtained. Then a ZGP OPO pumped by the Ho:YAG MOPA was demonstrated. The maximum average output powers of 5.48 W at 8.2 μm and 22.4 W at 2.8 μm were obtained, corresponding to the pulse width of

The continuous wave laser characteristics of a Tm:GdScO3 laser were researched in this work. Under the absorbed pump power of 19.11 W, a maximum output power of 4.41 W was obtained at 1978 nm, corresponding to the slope efficiency of 28.25%. With a quartz birefringent filter (BF), a broad wavelength tunable range from 1845 nm to 2006 nm was obtained, for the first time. Then, a long-pass filter was used to replace the quartz BF. A maximum output power of 3.21 W was obtained at 2002 nm, with the slope efficiency of 21.98%. The beam quality factors M 2 for horizontal and vertical directions were 1.14 and 1.11, respectively.

We report a 2 μm band high power pulsed all-polarization maintaining (PM) thulium-doped fiber laser based on the acousto-optic q-switching technique. It is constructed in a two-stage master-oscillator power amplifier (MOPA) configuration. A Q-switched seed laser was composed of a homemade 1559 nm fiber laser, a pair of fiber Bragg gratings (FBGs) with central wavelength at 2009 nm, a piece of single-cladding thulium-doped fiber (TDF) and an acoustic-optical modulator (AOM). Using a two-stage amplifier seeded by an acousto-optic modulator modulated pulsed laser, We achieved the laser with a central wavelength of 2009.71 nm, and the laser has a 3 dB linewidth of 0.09nm and output power of approximately 2.04 W. Based on the acousto-optic switch, the pulse width of 97 ns at a repetition rate of 20 kHz was obtained. The maximum peak-power of the fiber power amplifier is 2.1 kW and pulse energy is more than 204 μJ. This high power thulium-doped fiber laser has an all-fiber based configuration. We used a cladding power stripper (CPS) with matched passive fiber to remove residual pump light that leaked into cladding. The slope efficiency of the thulium-doped fiber power amplifier was 22.7%.

Most of the FBGs used in continues-wave thulium-doped fiber lasers are made in foreign companies. So we built up a fiber Bragg grating (FBG) writing platform to produce different parameter FBG for research, and a homemade FBG-based thulium-doped fiber laser testing system was experimentally demonstrated in this paper. Here homemade uniform FBGbased thulium fiber laser output characteristic was explored. The thulium-doped fiber laser was built up with two 793nm laser diodes as pump source, a thulium-doped fiber, a combiner and a pair of homemade FBGs. A 1916 nm thulium-doped fiber laser with output power of 20.87 W and slope efficiency of 41.29% and a 1917 nm thulium-doped fiber laser with output power of 19.53 W and slope efficiency of 38.56% were obtained by optimizing the thulium-doped fiber length, the operation temperature of the grating and the center wavelength of the grating.

We demonstrated a high-power long-wave infrared laser based on a polarization beam coupling technique. An average output power at $8.3~\unicode[STIX]{x03BC}\text{m}$ of 7.0 W was achieved at a maximum available pump power of 107.6 W, corresponding to an optical-to-optical conversion of 6.5%. The coupling efficiency of the polarization coupling system was calculated to be approximately 97.2%. With idler single resonance operation, a good beam quality factor of ${\sim}1.8$ combined with an output wavelength of $8.3~\unicode[STIX]{x03BC}\text{m}$ was obtained at the maximum output power.

Pumped by a 100 W Q-switched Ho:YAG laser at 2090.7 nm with pulse repetition frequency of 10 kHz, four types of high-power long-wave infrared ZnGeP2 (ZGP) subsequent optical parametric amplifier (OPA) based on optical parametric oscillator (OPO) with different types of phase matching (PM) of ZGP crystals were demonstrated. For the results of 8.2 µm output characteristics at the full incident pump power, Type-II PM ZGP OPO with Type-II PM ZGP OPA had the best M2 of 1.8 and lowest average output power of 9.2 W with the narrowest linewidth of 77 nm, while Type-I PM ZGP OPO with Type-I PM ZGP OPA had the worst M2 of 2.2 and the widest linewidth of 122 nm, and Type-II PM ZGP OPO with Type-I PM ZGP OPA had the highest average output power of 12.6 W, corresponding to overall optical conversion efficiency of 12.6% from Ho to long-wave infrared laser system.

An erratum is presented to correct the wrong picture in our paper.

In this paper, we demonstrate 1-kHz-repetition-rate laser ultrasound in carbon-fiber-reinforced plastics (CFRPs). A ZGP master oscillator and power amplifier (MOPA) system was used to generate high-repetition-rate laser radiation in the spectral range 3.2–3.4 μm. At the output wavelength of 3.4 μm, the maximum output energy of the ZGP MOPA system is 5.62 mJ with a pulse width of 24 ns, corresponding to a peak power of approximately 233.9 kW. The ultrasound was generated by the laser converted from 3.2 to 3.4 μm in the graphite/epoxy composite. The maximum ultrasonic signal amplitude in the CFRP sample was 36.2 mV in the condition of thermoelastic excitation at 3.4 μm. Ablation occurred in the CFRP sample when the energy fluence was over 90 mJ/cm2. Compared in different samples, laser-ultrasound generation was influenced by the wavelength of the laser.

In this paper, we demonstrate a new 2.1-µm Ho:(Sc

A high-efficiency and high-brightness Ho:YAG master-oscillator power-amplifier (MOPA) system dual-end pumped by Tm:YLF lasers was demonstrated. The maximum output power of 231 W at a wavelength of 2090.7 nm was achieved with pulse repetition frequency of 10 kHz and pulse width of 22.9 ns, corresponding to pulse energy of 23.1 mJ and peak power of ∼1 MW. The extraction efficiency of the amplifier system was more than 60%. The beam quality factor M2 was measured to be ∼1.05. Using the Ho:YAG MOPA system as the pump source, the ZnGeP2 optical parametric oscillator delivered an output power of 110 W, corresponding to slope efficiency of 62%.

In this paper we present a high power long-wave infrared ZnGeP

Continuous-wave Tm:YLF laser with two slab crystals was double end pumped by four fiber-coupled laser diodes at room temperature. A maximum continuous wave output power of 108 W for the slab Tm:YLF laser was generated, corresponding to a slope efficiency of 39.0 % and an optical-to-optical conversion efficiency of 35.5 % with respect to the incident pump power. The laser operated at 1,908.1 nm with a beam quality factor of M 2 ~ 2.9 at the highest output power.

In this Letter, we demonstrate a diode-pumped electro-optical cavity-dumped Tm:YAP laser for the first time to our knowledge. A pulse width of 7.1 ns is achieved at a wavelength of 1996.9 nm. A maximum output power of 3.02 W is obtained with a pump power of 58.8 W at a repetition rate of 100 kHz and a high-voltage time of 1000 ns, corresponding to an overall optical-to-optical conversion efficiency of 5.2%. In addition, we study the effect of repetition rate and high-voltage time on the output power characteristics of a cavity-dumped Tm:YAP laser.

High efficient and high power 2 $$\upmu $$ m room temperature Ho:YAG laser resonantly dual-end-pumped by two orthogonally polarized diode-pumped Tm:YLF lasers at 1.91 $$\upmu $$ m was demonstrated. A maximum continuous wave output power of 61.9 W was generated, corresponding to the slope efficiency of 63.9 % with respect to the incident pump power and optical-to-optical conversion efficiency of 59.9 %. At 20 kHz of the pulsed repetition frequency, we achieved a less than 25 ns FWHM pulse, with the maximum output energy per pulse of 2.84 mJ as well as a peak power of approximately 113.6 kW. A beam quality of $$M^{2}

We demonstrate a continuous-wave 2.1-µm laser with a new Ho:GdTaO4 crystal pumped by a 1940.3-nm Tm fiber laser at room temperature. The maximum output power of 11.2 W at 2068.39 nm was achieved, corresponding to a slope efficiency of 72.9%. Moreover, the beam quality factor was measured to be about 1.4 at the maximum output level.

In this paper, we demonstrate the continuous-wave and acousto-optical Q-switched performance of diode-pumped slab Ho:(Sc0.5Y0.5)2SiO5 (Ho:SYSO) laser at 2.1 µm for the first time. Two 1.91-µm laser diodes were used to pump the Ho:SYSO crystal. With a wing-pumping structure, at absorbed pump power of 44.7 W, the continuous wave slab Ho:SYSO laser produced 20.7 W maximum output power at 2097.9 nm, resulting in a slope efficiency of 53.1% with respect to the absorbed pump power. In the Q-switched regime, the slab Ho:SYSO laser produced up to 3.4 mJ pulse energy with 20 ns minimum pulse width at pulse repetition frequency of 5 kHz, corresponding to a peak power of 170 kW.

In this paper, we demonstrate a new 2.1-µm Ho:(Sc0.5Y0.5)2SiO5 (Ho:SYSO) laser at room temperature. The absorption and emission spectra of Ho:SYSO crystal were studied at temperature of 300 K. The strongest absorption peak of 5I7 level of Ho ions in SYSO crystal is located at 1943 nm with cross section of 0.79 × 10−20 cm2. The maximum emission cross section of 1.74 × 10−20 cm2 is located at 2032 nm. A 1940.3-nm narrow-linewidth Tm fiber was used to pump the Ho:SYSO crystal. At absorbed pump power of 20.4 W, the continuous wave Ho:SYSO laser yielded 10.3 W maximum output power at 2097.67 nm and 54.7% slope efficiency respect with absorbed pump power. In addition, we have estimated the beam quality factor (M2) of Ho:SYSO laser to be 1.7 near maximum output level.

We demonstrate a 102 W middle infrared ZnGeP2 (ZGP) optical parametric amplifier (OPA) pumped by a 2097-nm Q-switched Ho:YAG laser at a pulse repetition frequency of 10 kHz. The seed middle infrared laser was produced by a ZGP optical parametric oscillator. Its average power was 28.4 W pumped by a 50 W 2097-nm laser. By thermal lens compensation, the beam factor M2 reduced from 3.1 to 2.1. When the incident Ho pump power was 120 W, the middle infrared ZGP OPA yielded the maximum average output power of 102 W and slope efficiency of 61.7%. The overall optical conversion efficiency of 60% from Ho to middle infrared was obtained for the whole middle infrared laser system. In addition, at the maximum average output power, the beam quality factors of the middle infrared ZGP OPA were measured to be about 2.7 and 2.8 for horizontal and vertical directions, respectively.

We reported a high-energy, high-pulse-repetition-frequency Ho:YAG master oscillator and power amplifier (MOPA), which was resonantly dual-end pumped by Tm:YLF lasers at room temperature. At a pulse repetition frequency of 1 kHz, the Ho:YAG MOPA laser system produced a maximum pulse energy of 110.4 mJ with a 28 ns pulse width, corresponding to a peak power of approximately 3.94 MW. The output wavelength of the Ho:YAG MOPA laser system was 2090.9 nm. In addition, a beam quality factor M2 of about 1.7 was achieved at maximum output level.

In this paper we present a high power long-wave infrared ZnGeP2 (ZGP) optical parametric amplifier (OPA) pumped by a 2097-nm Q-switched Ho:YAG laser with pulse repetition frequency of 20 kHz. When the incident Ho pump power was 116.0 W, the maximum average output power of 11.4 W at 8.3 μm was achieved in the ZGP OPA. The optical conversion efficiency from Ho to long-wave infrared was about 9.8%. The ZGP OPA produced 30.4 ns long-wave infrared laser pulse. The beam quality factor (M2) of ZGP OPA was measured to be about 2.9 at the maximum average output power.

We present a far-infrared ZGP OPO laser pumped by a Q-switched Ho:YAG oscillator. The maximum output power of 8.2 W at 8.3μm with the beam quality factor M2 of ∼2.94 had been obtained.

A repetition-frequency-controllable double Q-switched (DQS) Ho:LuAG laser at 2098.34 nm with acousto-optic modulator (AOM) and Cr2+:ZnS saturable absorber (SA) was investigated. The maximum output power of 5.3 W was obtained at the AOM repetition frequency (RF) of 3.72 kHz, corresponding to the slope efficiency of 29.8%. The largest pulse energy of 2.8 mJ with the shortest pulse width of 54.2 ns was observed at the AOM RF of 2.64 kHz. Compared with the passively Q-switched Ho: LuAG laser, the DQS Ho: LuAG laser could generate shorter pulse width and larger pulse energy, and its RF could be controlled by the AOM RF. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)