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A high power Ho:YAP laser in-band pumped by a home-constructed Tm doped all fiber master oscillator power amplifier (MOPA) is reported. The optically polished and uncoated Ho:YAP laser yielded over 107 W of output power at ~2117.1 nm with 215.4 W of absorbed pump power, corresponding to a slope efficiency of 50.6% with respect to the absorbed pump power. The beam quality M2 parameter was measured at 80 W of output power to be ~3.2 and ~2.6 in x- and y-directions, respectively.

A high-peak-power, high-repetition-rate compact pulse burst 1064 nm laser from a master oscillator power amplifier is presented. The maximum pulse burst energy reaches 409.4 mJ with a pulse number of 86 and a single pulse energy of 4.8 mJ in a duration of 1 ms. A peak power of 2.5 MW is obtained in the pulse burst laser with a pulse width of 2.0 ns. The pulse burst laser has a good amplitude stability with a variation coefficient of 5.0%.

We report on mid-IR Fe:ZnSe master oscillator power amplifier (MOPA) laser system operating at room temperature (RT) pumped by a radiation of mechanically Q-switched Er:YAG laser operating at 2.94 m, at 3Hz repetition rate. The maximum output energy was as high as 250mJ in ~250 ns pulses. The RT gain-switched Fe:ZnSe master oscillator demonstrated tunability over 3.60-5.15 µm spectral range with a maximum output energy of ~3 mJ. The output energies of 12 (8), 34 (25) and 60 (48) mJ were demonstrated at 4.4 (4.1) µm in the 1st, 2nd and 3rd stages of amplifier, respectively, with a total pump energy of 200 mJ.

10 W level 90 ps MOPA laser with pulse repetition rate up to 700 kHz was developed. Passively Q-switched Nd:YVO 4 microchip 1064 nm laser was used as a master oscillator. Double-rod double-end-pumping configuration of two-pass Nd:YAG ring power amplifier was used to achieve high gain with efficient energy extraction. High quality laser beam with M2

We report on room temperature Fe:ZnSe MOPA system tunable over 3.6-5.2 µm pumped by radiation of Q-switched 2.94 µm Er:YAG laser. The maximum output energy was measured to be 60mJ under 200mJ of pump energy.

We demonstrated a cryogenically cooled Tm:Y2O3 master oscillator emitting around 1932.5 nm, which was tuned from 10 to 1000 Hz. Maximum pulse energy of 1.8 mJ (10 Hz) was achieved with 32 ns pulse duration.

Laser light in the yellow–green spectral range has to rely on frequency conversion as suitable direct emitting laser diodes are not available yet. With the help of newly developed and highly brilliant laser diodes, we are able to present a miniaturized laser module that emits laser light with an output power of more than 1.6 W at a wavelength of 576 nm. We achieved this by designing a small and compact module with a hybrid-integrated master oscillator power amplifier (MOPA) setup emitting at 1152 nm. For the second-harmonic generation of the laser light of the MOPA a periodically poled 42-mm-long volume LiNbO3 crystal is integrated. In this letter, we present the design and the electro-optical characteristics of this module.

A QCW LD pumped linearly polarized Nd3+:YAG/V3+:YAG laser operating at 1444 nm with high peak power of 62 kW is demonstated for the first time. The polarization extinction ratio of the 1444 nm output beam was higher than 1000:1 and the highest second-harmonic generation efficiency at 722 nm was 62.8%. A compact high-peak-power polarized Nd:YAG laser can be used as the master oscillator for a high energy system. In particular, a 722 nm laser is a viable source for biomedical applications such as photoacoustic imaging, oximetry, and tattoo removal.

A 10 W level master oscillator power amplifier (MOPA) laser with pulse repetition rate up to 1 MHz and 75–95 ps pulse duration was developed based on a passively Q -switched N d : Y V O 4 microchip 1064 nm laser as a master oscillator. A double-rod double-end-pumping configuration of two-pass Nd:YAG ring power amplifier was used to achieve high gain, near-Fourier-transform-limited pulses, and laser beam quality factor M 2 = 1.27 along both the horizontal and vertical directions.

We report a high-repetition-rate, high-peak-power laser diode (LD) pumped burst-mode 1064 nm laser from a Nd:YVO4/Nd:YAG master oscillator power amplifier. 10–100 kHz pulse burst in a duration up to 2 ms is achieved in LD end-pumped Nd:YVO4 acousto-optically Q-switched laser. After amplification with LD side-pumped Nd:YAG rod amplifiers, the single pulse energy reaches 73 mJ in 10 kHz pulse burst laser with a peak power of 7.8 MW.

The master oscillator power amplifier (MOPA) fiber laser has been around for several years but the bulk of applications use Q-switched fiber lasers. Now, with the processing capabilities of the Q-switched fiber laser fully explored, the MOPA fiber laser is getting revived attention. Laser-diode seeded MOPAs hold promise of arbitrarily modulated high-power laser output. Pulse-pumping the amplifiers to handle ON/OFF gating and low repetition rate pulse trains without overshoot or undershoot is of special interest.

We report, to the best of our knowledge, the first use of KY(WO4)2 and KG(WO4) acousto-optical Q-switches in 3-μm powerful lasers. Q-switches of two different designs (normal incidence with antireflection coatings, and Brewster-angle cut crystals) operate in lasers based on Er:YAG, Cr:Yb:Ho:YSGG, and Cr:Er:YSGG laser crystals. Gain and lifetime of laser crystals significantly influence the regime of Q-switched generation. Er:YAG and Cr:Yb:Ho:YSGG lasers deliver pulses with 10.8 mJ and 17.5 mJ energy, respectively. Pulses with energy of 29.6 mJ and duration of 75 ns in the TEM00 mode are obtained in a Cr:Er:YSGG laser. The energy is scaled up to 85.7 mJ in the two-stage master oscillator power amplifier system. Powerful laser systems of this kind are in the region of interest for pumping other mid-IR laser media (e.g., Fe:ZnSe and Fe:CdSe), OPOs, CO2 lasers, and amplifiers. Preliminary experiments on microstructuring of transparent materials by the laser-induced backside wet etching method demonstrate the potential of such lasers to build the foundation for dye-free tissue and cell engineering concepts.

We investigate thermal effects in a nested-cavity doubly resonant optical parametric oscillator (NesCOPO), pumped by a high repetition rate laser, and the consequences on its spectral characteristics.

A highly adaptable fiber laser with pulse-on-demand and precision pulse-duration tuning is presented. It is based on a compact optical design combining the gain-switching technique with the all-fiber master oscillator and pump-recovery amplifier architecture. The approach of laser-pulse stability control by compensation pumping and pulse-duration control by changing the pump wavelength are introduced. In order to prove the concept, a laser setup capable of producing laser pulses with an average power of up to 30 W and a peak power of approximately 1 kW at an improved efficiency and an arbitrary repetition rate is presented.

We demonstrate for the first time a fibre Raman laser delivering record-setting energy (60 nJ) of double-scale picofemtosecond pulses at wavelength of 1270 nm, which is of great interest in bio-medical applications. A Stokes wave was generated in single-stage Raman conversion of amplified radiation from a mode-locked F8 Yb-doped laser passing through a synchronously pumped phosphosilicate fibre ring cavity. The converted radiation at 1270 nm amounting to 47% of the total Raman laser output was maximised by tuning the repetition rate of the pulses generated in the Yb-doped master oscillator to the fundamental inter-mode spacing frequency of the phosphosilicate fibre cavity.

The first build of the new optical reference cavity is complete and the cavity is operational at NPL. A commercial Nd:YAG laser is stabilised to it, and the ultra-stable laser system is serving as a master oscillator to transfer stability through a frequency comb to the multiple microwave and optical clocks at NPL (Nicolodi et al in Nat Photon 8:219–223, 2014, [2]).

We report on a RT gain-switched Fe:ZnSe master oscillator power amplifier (MOPA) system tunable over 3.8–5.0 µm pumped by radiation of Er:YAG laser operating at 2.94 µm. The mechanically Q-switched Er:YAG laser with output energy up to 220 mJ was used as a pump source for a master oscillator and three-stage power amplifier. The maximum output energies in 200 ns pulses exceeded 60, 56, and 48 mJ at 4.4, 4.3, and 4.1 µm, respectively, under 220 mJ of pump energy. The extraction energy efficiencies were measured to be 25, 30, and 40% at the first, second, and third stages, respectively.

We demonstrate a diode-pump Tm3+-doped all-fiber laser operating at 1908 nm based on a master oscillator power amplifier (MOPA) configuration. In our work, 152 W of laser output power is generated by a total incident pump power of 434 W at 790 nm, corresponding to the total optical efficiency of 35%. The laser wavelength is 1908.29 nm. To the best of our knowledge, it is the highest output power reached around 1908 nm with such a narrow linewidth of 0.18 nm based on a MOPA configuration.

We present a power-scalable high-power single-frequency continuous-wave 1342 nm master oscillator power amplifier (MOPA) system that consists of a polarized single-frequency 1342 nm LD seed laser, a Raman fiber preamplifier, and a three-stage N d : Y V O 4 power amplifier. The single-frequency output power of 30 W at 1342 nm is achieved with the beam quality factors M 2 = 1 . 26 , and the power stability for 1 h is better than ± 0 . 5 % .

This work reports, for the first time, the results of the development and study of an Yb-fibre master oscillator, in which a variety of mode-locked regimes may be created in a controlled way electronically, including regimes producing picosecond single-scale pulses and double-scale trains. The possibility of electronic switching among generation regimes of the developed laser relies on a non-linear amplifying loop mirror of a new generation featuring two stretches of active fibre with two independently controlled pump modules. This work presents a detailed description of the experimental set-up and discusses the application prospects of the newly developed universal laser.

NASA Goddard Space Flight Center has been developing an integrated path differential absorption (IPDA)lidar instrument concept to measure the column concentrations of atmospheric carbon dioxide (CO 2 )from space. We will discuss the development effort of a space-qualified, single frequency, fiber-based master oscillator power amplifier with >450 μJ pulse energy, 7.5 kHz repetition rate, single spatial mode, and > 20 dB polarization extinction.

A master oscillator-power amplifier CO laser system emitting a short train of single line, two-line, or multi-line nanosecond pulses with the train duration of ~1 μs was developed by implementation of the master oscillator with mode-locking and Q-switching.

We review possible alternatives for the realization of the LISA laser assembly against the requirements and present a concept for a tailored master oscillator fiber power amplifier solution. An all-solid-state, all- fiber coupled approach with a Nd:YAG NPRO seed appears particularly attractive due to the possibility to combine excellent spectral properties and high output powers with superior environmental robustness.

International audience; Coherent beam combining aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. Different architectures are proposed in the literature, either based on lasers in a passive extended-cavity or amplifiers seeded by a master oscillator. We compare the different approaches for high-brightness tapered laser devices.

We report a compact and robust laser system capable of generating diffraction-limited pulses tunable from the red- through mid- IR that exploits a repetition–rate switchable master oscillator and single-pass OPO design with PPLN and BIBO crystals.

We report a high power transverse-mode-switchable fiber laser in a master oscillator power amplifier (MOPA) configuration. Switchable LP01 and LP11 modes with output power of 500 W level were obtained based on active mode control.

We report the development of a compact high power laser system based on the Master Oscillator Power Amplifier concept and the microchip laser technology. 200 MW Gaussian beam was obtained and used for generating air-breakdown.

We demonstrate a high power high beam quality diode-pumped 1 112-nm Nd:YAG master-oscillator poweramplifier (MOPA) laser system. To increase the extraction efficiency and output power, a four-pass amplifier scheme is employed. Finally, the injected laser output power is amplified from 26 to 64 W with beam quality factor M2=2.85. Furthermore, a theoretical model that takes the temporal overlap inversion number dynamics into account is employed to analyze the performance of the MOPA laser system, and a good agreement with the experimental data is obtained.

We presented a 125 W single-frequency continuous-wave (CW) 1064 nm laser, where a homemade 50.3 W single-frequency CW high quality Nd:YVO4 laser and a two-stage dual-end-pumped master-oscillator power amplifier (MOPA) acted as the seed source and amplifier, respectively. As a result, a maximum output power of 125.2 W was achieved with the incident pump power of 200 W. The optical-to-optical conversion efficiency and the overall amplified power gain were 43.3% and 3.28%, respectively. The measured beam quality M 2 and the long-term power stability of the 1064 nm amplifier during 8 h were better than 1.28 and ±0.73%, respectively. Additionally, the power extraction efficiency of the designed MOPA system was further investigated and the results revealed that the key of improvement of the power extraction efficiency of the MOPA system was employing a high-power single-frequency CW laser as the master oscillator.

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.

The study was to develop high-power stable Nd:YAG master oscillator for MOPA laser system. Output power of 4.5 W was achieved with 30 W of pump power for wide range of Q-switched lasing repetition rate. 15mJ@300Hz lasing of 10 ns pulses was achieved after optimization.

Multiple variants of the Diode Pumped Alkali Laser (DPAL) have recently been demonstrated at the Air Force Research Laboratory (AFRL). Highlights of this ongoing research effort include: a) a 571W rubidium (Rb) based Master Oscillator Power Amplifier (MOPA) with a gain (2α) of 0.48 cm-1, b) a rubidium-cesium (Cs) Multi-Alkali Multi-Line (MAML) laser that simultaneously lases at both 795 nm and 895 nm, and c) a 1.5 kW resonantly pumped potassium (K) DPAL with a slope efficiency of 50%. The common factor among these experiments is the use of a flowing alkali test bed.

To increase a peak power of carbon monoxide laser emitting nanosecond pulses a Master Oscillator-Power Amplifier (MOPA) laser system was developed. The MOPA CO-laser system employed one and the same gain medium of wide-aperture pulsed electron-beam-sustained-discharge CO-laser facility. Amplification parameters include gain and saturation intensity of amplifying media. The MOPA CO-laser system emitted a train of nanosecond pulses with peak power up to ~ 0.1 MW on a single spectral line and up to ~ 0.4 MW with multiline spectrum.

We report a high-repetition-rate, high-pulse-energy master oscillator power amplifier (MOPA) laser system, in which the seed laser from the Nd:YAG rod-based oscillator cavity dumped at 500 kHz, was scaled up consecutively by a four-stage Nd:YVO4 preamplifier and a two-stage Nd:YAG zigzag slab main amplifier. The laser pulsed output with the average power of 510 W was achieved, with the efficiency extraction of 26.6% at the main amplifier stage and the single-pulse energy of 1.02 mJ.

A master oscillator power amplifier (MOPA) system in which the output from an end-pumped Nd:YAG oscillator cavity dumped at 500 kHz is scaled up by a four-stage Nd:YVO4 amplifier is reported. Decrease in extraction efficiency of the amplifier chain with crystals different from that in the oscillator was analyzed. With the 5.4 W seed output, 118 W of power was extracted from the amplifier chain at the pump power of 345 W, with an extraction efficiency of 34.2% and an overall optical–optical efficiency of 30.9% for the MOPA system. The beam quality factors were measured as Mx2=1.45 and My2=1.59 in two orthogonal directions, respectively.

Initiation of a self-sustained volume discharge in CO2-containing gaseous mixtures kept under a pressure of up to 10 atm with the aim of amplifying picosecond IR pulses is considered. Experimental electricdischarge and optical characteristics of a wide-aperture high-pressure CO2 amplifier are presented. The feasibility of designing terawatt laser equipment with a master oscillator and preamplifier is discussed.

We present a fiber amplifier based laser at 1028 nm frequency converted to 257 nm. A pulse expansion currently set up for the system is also presented. The systems are used in cooling of highly relativitsic ion beams at storage rings.

Technical Integration Line (TIL), which is being constructed at CAEP, is the prototype of Shenguang III fusion laser facility. Experimental results during the first integrated tests on the first line demonstrate that the laser system architecture from master oscillator through the laser amplifiers can meet the requirement of TIL engineering design. In this paper, brief introduction of TIL and main experiment results are presented.

The results of experimental and theoretical studies of operation regimes of a pulsed chemical D2–F2–CO2 UV initiated laser are presented. The influence of particular mixture components, the power of the UV radiation source, and the resonator's characteristics on the output radiation parameters are experimentally studied on the “Kaiman” setup. The results of theoretical simulation obtained using the proposed scheme correspond sufficiently to those obtained experimentally. A description is given of the pulsed D2–F2–CO2 UV initiated laser “Flash-1” that provides for radiation pulses of 18 J with a 2.6–3.5 μs duration in the 10-micron range. A detailed description is given of the precision diagnostics of dark reactions occurring during the mixture preparations and affecting the efficiency of energy extraction in the course of generation.

We report a high power transverse-mode-switchable fiber laser in a master oscillator power amplifier (MOPA) configuration. The output modes of a few-mode fiber amplifier can be actively controlled by the input polarization state of the fundamental mode seed laser using SPGD algorithm. A fast, stable and safety mode switching between LP01 and LP11 modes is achieved in the amplifier at output power of 500 W level.

In Chap. 2 we examined rather simple NPL designs for searching for and studying characteristics of laser active media, but there are also more complex nuclear laser devices. As a rule, they are structural elements of multichannel reactor lasers operating in stationary or pulsed modes, and are intended to study the specifics of their operation. This chapter examines some of these devices, whether in operation or still being designed.