A spectroscopic analysis is performed on Er3+ (4f11) ions doped in order to assess this material for its potential as a near infrared laser. The Judd-Ofelt model is applied to the room temperature absorption intensities of Er³⁺ (4f¹¹) in NaBi(WO₄)₂ to obtain the three phenomenological intensity parameters: Ω₂ = 5.50 x 10^-20 cm², Ω₄ = 1.00 x 10^-20 cm², and Ω6 = 0.71 x 10^-20 cm². The intensity parameters are then used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios for the Er³⁺ transitions from the excited state multiplet manifolds to the lower-lying manifold states. Using the radiative decay rates for the Er³⁺ (4f¹¹) transitions between the corresponding excited states and the lower-lying states, the radiative lifetimes of eight excited states of Er³⁺ are determined in this host. Using the room temperature fluorescence lifetime and the radiative lifetime of the ⁴I_13/2→⁴I_15/2 (1.52 µm) transition of Er³⁺ in NaBi(WO₄)₂, the quantum efficiency is determined to be 84% for this laser material.

It is demonstrated that pulsed laser deposition is a promising "alternative route" for synthesis of middle infrared laser media based on chromium doped ZnS crystalline thin films with a precisely controllable concentration of dopant. The deposition rate and thickness of the thin films synthesized in our experiments varied for 0.017 to 0.109 nm per pulse and 200 nm up to 12 μm, respectively, depending on the laser energy density, number of pulses, and target-substrate distance. Cr concentration in the target material and grown thin film measured by different techniques were very close to each other for a dynamic range of Cr concentration from ~ 10¹⁹ to 3.5 × 10²⁰ cm^-3. Thin film features luminescence band which is similar to the band in bulk crystal (slightly blue-shifted). The emission lifetime of Cr²⁺: ZnS films with Cr²⁺ concentration of ~2 × 10¹⁹ cm^-3 was measured to be ~3 μs. The emission lifetime was shortened to 1 μs for 1.8 × 10²⁰ cm^-3 and to 0.67 μs for 3.5 × 10²⁰ cm^-3 concentration of chromium due to the concentration quenching. Spectroscopic study shows that Cr²⁺:ZnS thin films synthesized by pulsed laser deposition are promising for middle infrared lasing.

In this work we report an experimental demonstration of broadband wavelength self-tuning in Rb₅Nd(MoO₄)₄ laser crystal (RNM) together with a theoretical treatment of the system based on its birefringence properties. The experimental self-frequency tuning of the laser emission along the free spectral range of the RNM crystal (1060-1070 nm) was obtained by rotating the birefringent gain plate in its own plane. To investigate the tuning characteristics of the spectral filter, we have used the Jones-vector formalism. The calculated wavelength-selective tuning matches very precisely the experimental observations.

Diode pumping of a laser-stress-free, Nd( 5 % at.):KGW, grown by top nucleated floating crystal (TNFC) method, is presented. The diode-pumped laser was operated both in the free-running and passively Q-switched operating modes. Under optimized conditions of resonator and optics, the Nd:KGW disk (1.3 mm in thickness), produced at room temperature an efficient free-running, TEM00 output with maximum power of 0.4-W, with 75 % slope efficiency and 51 % total laser efficiency. Under slightly different experimental conditions the laser was passively Q-switched by using Cr⁴⁺:YAG as saturable absorber. The passively Q-switched laser produced modulated pulses at average frequencies in the range of 10-20 kHz, with pulsewidth of ≈180 nsec, with an average output power obtained was 30 mW at the maximumpumping power level. The results presented here indicate the potential Nd:KGW crystals grown by TNFC growth method, as candidates for concentrated, stress free diode pumped microlasers in a large variety of wavelengths, including the eye-safe range.

Gadolinium Gallium Garnet single crystals doped with cobalt ions are used for suppression of parasitic as edge cladding layers in Nd:Gd₃Ga₅O₁₂ (Nd:GGG) crystal amplifier plates for heat capacity and other high power solid-state laser applications. Co:GGG absorbs at the lasing wavelength of 1062 nm. Nd:GGG amplifier plates with edge cladding of Co:GGG of adjusted absorption coefficient at 1062 nm will be used as adhesive-free bonded (AFB) composite crystal components in a heat capacity laser system at Lawrence Livermore National Laboratory. Composite formation of Nd:GGG and Co:GGG involves heat treatment. The absorption coefficient of the as-grown Co:GGG single crystal changes as function of heat treatment. We report on a method of reversibly adjusting the absorption coefficient of Co:GGG in a certain range, e.g. for a specific Co ion concentration of 0.0046% between 0.45/cm and 0.95/cm. The interpretation of the reversible adjustment of absorption coefficients based on absorption spectra, site symmetry and cobalt ion valency will be presented

Optical quenching of the THz inter-sub-band p-Ge laser (tunable in the wavelength range 70-200 micron with ~1W output power) by Nd:YAG laser radiation has been investigated. YAG laser pulses were coupled into a p-Ge laser cavity through a SrTiO₃ laser mirror, which is highly reflecting at cryogenic temperatures for THz frequencies and transparent for visible and near-IR light. Fast quenching of the p-Ge laser emission intensity was observed and attributed to free carrier absorption by optically generated electron-hole pairs in a thin layer of the active p-Ge crystal end surface. The effect also occurs when the interband absorption is confined to optically stimulated intracavity Si or GaAs spacers, which are transparent in the far-IR, placed between the SrTiO₃ laser mirror and the active crystal end face. Such fast quenching of the p-Ge laser might be used to sharpen the trailing edge of the far-IR emission pulse for time-resolved or cavity-ring-down spectroscopic applications. Direct-gap semiconductor spacers might be used as fast, optically controlled intracavity modulators for active mode-locking.

We introduce a novel cost-effective concept of generating broadly tunable ultrashort laser pulses at unprecedented stability. In the heart of the proposed and implemented laser system is a high-repetition rate, high-energy oscillator, generating picosecond pulses at the energy level sufficient for ultra-broadband continuum generation and parametric frequency conversion. Up to 10-W average of average power can be generated at the energy level of 10 μJ per pulse. Frequency conversion to a broadband continuum is achieved in specially selected optical fibers with enhanced nonlinearity via cascaded stimulated Raman scattering.

The first room temperature stable tunable color center (CC) distributed feedback (DFB) laser is described. The laser utilizes stabilized F₂+** centers in LiF (LiF:F₂+**) as a gain medium. Tunable DFB lasing was achieved in the near IR region (882 - 962 nm) with a lasing linewidth of less than 0.2 cm-1. The lasing threshold was found to be 1.2 mJ, while the slope efficiency with respect to pump energy was found to be as high as 3%.

An efficient method to make multi-spectral laser light having any selected pulsed duration in the range of 100 ns to 1 μs has been demonstrated in the laboratory. This laser system, based on the alexandrite tunable solid-state gain medium, which is tunable in its fundamental between 720 and 800 nm, was constructed near the gain maximum of 755 nm. A novel intracavity pulse-stretcher provides control of the pulse duration up to about 5 μs using the Pockels effect. In the demonstration prototype, however, the pulse duration was restricted to 500 ns to maintain the peak power needed for efficient nonlinear conversion. Following an amplification stage, Raman shifting in hydrogen gas was used to achieve efficient wavelength conversion to 1100 nm. The Raman shifted beam was frequency doubled to 550 nm using two BBO crystals arranged for walk-off compensation. The result was a convenient source of light whose spectral content, pulse duration, as well as other parameters, could be critically controlled.

Five kinds of the laser passive modulators: single crystal semiconductor wafers, plastic dye sheets, lithium fluoride crystals containing F₂^- color center, chromium yttrium aluminum garnet crystals and ionic color filter glass that can Q-switched modulate, mode-locked modulate, and Q-switched mode-locking modulate the conventional flash-lamp pumped Nd:hosted lasers, Er:Glass eye-safe solid-state lasers as well as all those of diode-pumped Nd:hosted and Er:Glass eye-safe microchip lasers are presented. Theoretical model are proposed and the detail analysis are presented.

Challenges typically associated with efficient operation of bulk solid-state erbium lasers operating on the eyesafe (⁴I_13/2 → ⁴I_15/2) transition have been effectively overcome using a high-brightness fiber laser as a pump source. We report exceptional performance in a variety of laser hosts resonantly pumped by a cw, high-average-power erbium fiber laser. Herein we present results from resonantly pumped erbium-doped YAG, LuAG, YLF, YAlO₃, and YVO₄, in cw and repetitively Q-switched operation. Most notable results include 9.5 W of near-diffraction-limited output from an Er:YAG laser at 1.645 μm, Q-switched at 10 kHz with 40 ns pulsewidth (25 kW peak power) as well as 3.4 μJ/pulse with 21 ns pulses at 1.1 kHz (160 kW peak). We have achieved overall optical conversion efficiency greater than 50% with incident slope efficiency >60%. This is, to our knowledge, the highest performance (average power and conversion efficiency) obtained from a bulk solid-state Q-switched erbium laser. To demonstrate the utility of such sources, we also present results from second harmonic generation to 822nm, as well as a periodically poled lithium niobate optical parametric oscillator generating tunable 2.5 - 3.8 micron output.

A miniature diode pumped Er,Yb:glass laser has been developed at the Night Vision and Electronic Sensors Directorate, U. S. Army CECOM (NVESD) for soldier applications. This device uses a single laser diode at 925 nm to end pump a 200µm x 3 mm volume of Er,Yb:glass gain media. A Co²⁺:MgAl₂O₄ passive Q-switch is used to produce 2 nanosecond pulses at a repetition rate from single shot to 20 Hertz. A nominal pulse energy of 100 microjoules is emitted, corresponds to a peak power of 50 kilowatts, which is sufficient for ranging to over 2 kilometer. The Eyesafe Microlaser was designed and demonstrated to operate over a wide temperature range without temperature control of the pump laser, a feature important for soldier applications. An desirable feature of Er,Yb:glass lasers is that they emit directly at 1.54 microns, which is important for eye safe operation and low cost fabrication.

In this paper, pulsed operation of the 980 nm diode-pumped Yb:Er:glass solid-state-laser operating at 1543 nm using Co:Spinel saturable absorber is described. The Yb:Er:glass gain medium was end-pumped using a 10 W fiber-coupled 980 nm laser diode. Passively q-switched laser operation was accomplished for both CW and quasi-CW operations. Up to 2 mm thick uncoated Co:Spinel samples were used for our tests. With quasi-CW pumping, pulsewidths greater than 20 ns, pulse energies of greater than 250 μJ and free-running PRFs up to 1.2 kHz have been demonstrated. So far, up to 3 % optical-to-optical efficiency has been achieved with uncoated q-switch materials. Currently, this laser is being developed for pumping a long-wave IR (8-12 μm) optical parametric oscillator for use in spectrapolarimetric applications.

Experimental results describing pulsed lasers operating near 3.9 μm on the Ho³⁺ (⁵I₅-⁵I₆) transition in highly-doped (> 10 at. %) barium yttrium fluoride (BaY₂F₈ or BYF) will be presented. The ⁵I₅ manifolds in Ho:BYF were pumped using a flashlamp excited, free-running Cr:LiSAF laser tuned to the Ho³⁺ absorption peak near 889nm. Ho³⁺ concentrations of 10%, 20%, 30% and 40% in BYF were lased in a simple end-pumped resonator. Some similar data was also obtained in 10% and 20% Ho:YLF. The highest 3.9 μm pulse energy obtained in the comparative study was 55 mJ (at ~10% optical-to-optical efficiency) using the 30% Ho:BYF crystal. A dual end-pumped laser in 30% Ho:BYF was also demonstrated, providing a pulse energy of 90 mJ in a near diffraction limited beam (M² ~ 1.2). Emission decay data was taken to shed light on the observed dependence of laser efficiency on holmium concentration and excitation density. The lifetimes of both lasing levels (⁵I₅ and ⁵I₆) deviate rather significantly from their low-concentration values. Plausible energy transfer processes that may be responsible for the observed trends in the laser and emission data will also be discussed.

In the past five years diode-pumped Q-switched vanadate and YAG lasers with 355 nm and 266 nm output have advanced in power level and reliability and are now qualified in many industrial processes. In this paper we will discuss the design and performance of these lasers with consideration of available power and wavelength of laser diodes, selection of materials for the non-linear crystals, trades offs for end-pumped and side-pumped designs, and scaling of such lasers to higher power levels. Performance characteristics to be discussed include power and efficiency, ramping behavior, beam quality, and pulse-to-pulse stability.

A compact parametric oscillator (OPO) with intracavity sum-frequency generation (SFG) to generate 293 nm UV laser irradiation, was developed. The OPO/SFG device was pumped by a 100 Hz Nd:YAG laser (1064 nm) of own design, including subsequent second harmonic generation (SHG) in an external periodically poled KTiOPO₄ (KTP) crystal. The whole system could be used to deliver more than 30 μJ laser irradiation per pulse (100 Hz) at 293 nm. The UV laser light was introduced in an optical fiber attached to a sample compartment allowing detection of fluorescence emission using a commercial spectrometer. Aqueous samples containing biomolecules (ovalbumin) or bacteria spores (Bacillus subtilis) were excited by the UV-light at 293 nm resulting in strong fluorescence emission in the range 325 - 600 nm.

We introduce a novel type of cw green laser source, the Protera 532, based on the intracavity frequency doubling of an extended-cavity, surface-emitting diode laser. The distinguishing characteristics of this platform are high compactness and efficiency in a stable, single-longitudinal mode with beam quality M² < 1.2. The laser design is based on the previously reported NECSEL architecture used for 488nm lasers, and includes several novel features to accommodate different types of nonlinear optical materials. The infrared laser die wavelength is increased from 976nm to 1064nm without compromising performance or reliability. The intracavity frequency doubling to 532nm has been demonstrated with both bulk and periodically poled nonlinear materials, with single-ended cw power outputs of greater than 30 mW.

Although powerful (2.8 W) blue emission at 473 nm was recently reported, the design of low-cost compact and efficient 473 nm source failed so far. We have theoretically and experimentally analyzed the operation of a simple 2.1 mm long microchip assembly pumped by a 100x1 μm laser diode and found several ways to improve the efficiency of such a laser. As a first result, we achieved high beam quality (M²<1.2) 40 mW CW operation @ 473 nm with less than 900 mW launched power (5% efficiency) and small low-frequency (10Hz-20 kHz) noise. Multi-frequency operation however led to high-frequency noise (green problem). To our best knowledge, this is the highest efficiency obtained with a linear cavity. In this paper, we model and measure thermal lensing, pump, 946 nm and 473 nm beam size and power evolution within the MCA. Nd concentration was left unoptimized in previously reported experiments to its standard value (1.1%). Optimum Nd concentration is shown to generally be greater than 1% and is compatible with efficient low-noise single-frequency operation.

We report on robustness testing of a highly reliable frequency-doubled, external cavity semiconductor laser (DECSL). The laser module has been demonstrated to survive 6G operating vibration swept from 100 Hz to 500 Hz at 0.25 octaves/min. Impact shock to destruction was performed, and the unit passed operating specifications up to 300G. Good pointing stability and laser start times are shown as a function of repeated environmental temperature cycling between operating extremes.

We report on cavity-enhanced second-harmonic generation of 488 nm radiation in a 5 mm long periodically poled KTiOPO4 (PPKTP) crystal pumped by the output of a single-mode 976 nm semiconductor external cavity laser. At a pump laser output power of 660 mW, a mode-matching efficiency into an enhancement cavity of 65 % was observed. A maximum power of 156 mW at 488 nm was generated in the enhancement cavity of which 130 mW was coupled out. Under these pump laser conditions an overall optical conversion efficiency of 20 % and an overall electrical to optical efficiency of 9 % was measured. Both the spatial and spectral properties of the 488 nm beam are of very high quality. Typically, a near-diffraction-limited beam with M²<1.1 is produced with low astigmatism and little ellipticity.

A power scaling investigation of a Yb:YAG rod laser configured with a stable resonator is described. A dual laser rod architecture was chosen to minimize thermal birefringence. An investigation of the medium was carried out by measuring the aberrations during lasing conditions. The limitation of beam quality seems to be due to aberrations related to the mode-medium interaction. The experiments measured the severity of the aberrations and the Zernike coefficients were determined. A simple model provided some insight into the operation of the laser. It has been noted that under certain conditions, spherical aberration can improve beam quality.

This work describes recent progress in the development of a solid-state disk laser that uses composite laser disks in active mirror configuration, edge-pumping, and cooling by microchannel-type heat exchanger. An innovative pressure clamping technique was used to mitigate thermo-mechanical distortions in the disk. A test article Yb:glass disk was operated at a thermal load corresponding to about 1 kW laser output in a steady-state regime with surface temperatures around 90°C while exhibiting less than λ_Laser/10 rms phase error. Measured pump uniformity approaching 90% validated the edge-pumping architecture.

We report initial operation of the Mercury laser with seven 4 x 6 cm S-FAP amplifier slabs pumped by four 80 kW diode arrays. The system produced up to 33.5 J single shot, 23.5 J at 5 Hz, and 10 J at 10 Hz for 20 minute runs at 1047 nm. During the initial campaign, more than 2.8 x 10⁴ shots were accumulated on the system. The beam quality of the system was measured to be 2.8 x 6.3 times diffraction limited at 110 W of output, with 96% of the energy in a 5X diffraction limited spot. Static wavefront glass plates were used to correct for the low order distortions in the slabs due to fabrication and thermal loading. Scaling of crystal grown has begun with the first full size slab produced from large diameter growth. Using an energetics optimization code we find the beam aperture is scalable up to 20 x 30 cm and 4.2 kJ.

We report on the laser characteristics of solid-state dye lasers pumped directly by a pulsed red diode laser. A 1.6-mm thick disk of Oxazine 725 in modified PMMA was excited longitudinally in a nearly hemispherical resonator at ≅671 nm. We operated at rep rates up to 1 kHz, with only a modest drop in energy per pulse at the highest rep rates. (The energy at 1 kHz is ≅83% of that measured at 1 Hz.) The spectral output of this solid-state dye laser was centered at ≅740 nm with a bandwidth (FWHM) of ≅10.5 nm. For a pump pulse of 230 ns (FWHM), the dye laser output was ≅155 ns in duration, and tracked the pump pulse well after turn on. The maximum observed efficiency for a sample containing Ox 725 in modified PMMA was 18%. Data on other solid dye media are also presented.

The photophysical and lasing properties of a number of near infrared laser dyes from different dye classes - extended rhodamines, oxazines, cyanine and styryl dyes - predominantly in liquids but also in poly(methyl methacrylate) (PMMA) based hosts are reported in this paper. The different dyes have been found to exhibit fluorescence quantum efficiencies in the range of 0.01-0.88 in solution. The fluorescence efficiency for a number of the dyes has been found to be heavily dependent on the solvent characteristics. Laser slope efficiencies in the range of 20-66% have been recorded for the dyes under nanosecond laser pumping at or close to the wavelength of their absorption maximum. The lasing wavelengths of the samples were found to range from 647 nm to 815 nm. Some differences in the lasing efficiency has been noted between the behaviour of the liquid and solid-state dye samples, in particular for the dye Oxazine 1. A number of the dye/solvent combinations have been further tested in a flashlamp pumped dye laser apparatus with success, with moderate laser efficiency at lasing wavelengths ranging from 692 to 824 nm having been achieved.

Tunable solid-state dye lasers operating in the blue-green spectral region are attractive for a variety of applications. An important consideration in assessing the viability of this technology is the service life of the gain medium, which is presently limited by dye photodegradation. In this study, solid polymeric samples consisting of the coumarin dye C540A in modified PMMA were subjected to controlled photodegradation tests. The excitation laser was a flashlamp-pumped dye laser operating at 440 nm with a pulse duration of 1 μs. A complementary set of data was obtained for dye in solution phase for comparison purposes. Photophysical properties of C540A in water solution of polymethacrylic acid (PMAA) have been investigated with a view to assess the suitability of the sequestering polymer (PMAA) as an effective additive to facilitate use of a water medium for highly efficient blue-green dye lasers. Lasing action of C540A in aqueous PMAA has been realized using flashlamp-pumped laser system, yielding excellent laser efficiencies superior to that achieved in ethanolic solutions with the same dye. Laser characterization of dye in media included measurement of laser threshold, slope efficiency, pulse duration and output wavelength.

A compact tunable UV OPO laser system has been used for the real-time detection of aromatic hydrocarbon hazardous air pollution vapors at sub-ppb levels using the jet-REMPI (jet-cooled Resonance Enhanced Multi-Photon Ionization) technique. By combining spectral and molecular mass detection, this technique provides high chemical selectivity, allowing species identification even during direct sampling of complex real-world samples. The inherent sensitivity of the jet-REMPI also allows direct real-time detection of trace species without pre-concentration. However, applications of the technique have been confined to the laboratory, requiring a complex and delicate tunable UV laser source and mass spectrometer. The results of applying a less complex, compact low-resolution OPO laser system are presented, with the goal of furthering the development a complete compact jet-REMPI instrument.

We have designed and built two versions of a space-qualifiable, single-frequency Nd:YAG laser. Our approach to frequency stabilization of the seeded oscillator is a variation of the “ramp and fire” technique. In this design, the length of the pulsed laser cavity is periodically varied until a resonance with the seed laser is optically detected. At that point the pulsed laser is fired, ensuring that it is in resonance with the seed laser. For one of the lasers the resulting single frequency pulses are amplified and frequency tripled. This system operates at 50 Hz and provides over 50 mJ/pulse of single-frequency 355 nm output. It has been integrated into the GLOW (Goddard Lidar Observatory for Winds) mobile Doppler lidar system for field testing. The second laser is a 20o Hz oscillator only system that is frequency doubled for use in the High Spectral Resolution Lidar (HSRL) system being built at NASA Langley Research Center. It provides 4 mJ of single-frequency 532 nm output that has a spectral purity of >10,000. In this paper we describe the design details, environmental testing, and integration of these lasers into their respective lidar systems.

Two methods of compensation of thermal lensing in high wer terbium gallium garnet (TGG) Faraday isolators have been investigated in detail: compensation by means of an ordinary negative lens and compensation using FK51 Schott glass possessing a negative dn/dT. Key thermo-optic constants for TGG crystals and FK51 glass were measured. We find that the contribution of the photo-elastic effect to the total thermal lens cannot be neglected either for TGG or for FK51. We define a figure of merit for compensating glass and show that for FK51, an ordinary negative lens with an optimal focus is more efficient, but requires physical repositioning of the lens for different laser powers. In contrast, the use of FK51 as a compensating element is passive and works at any laser power, but is less effective than simple telescopic compensation. The efficiency of adaptive compensation can be considerably enhanced by using a compensating glass with figure of merit more than 50, a crystal with natural birefringence or gel.

Generation of a giant pulse of Er:YAG laser is complicated mainly due to the properties of the Er:YAG active medium itself. It is caused by the short lifetime of the upper laser level of Er:YAG crystal and a small gain for one pass of the radiation through the active medium. In our case, a specially designed LiNbO₃ electrooptic shutter was used for Q-switching of Er:YAG laser. Brewster angles were employed at the LiNbO₃ crystal faces to avoid the inclusion of a polarizer into the resonator. Even if Er:YAG crystal emission is naturally unpolarized we have found that polarization sensitive reflections at two Brewster-cut ends of Pockels cell are sufficient to reach extinction ratio necessary for giant pulse generation. By help of theoretical analysis based on Jones calculus was found the dependency of Pockels cell radiation transmission on applied voltage. Calculated transmission of Brewster-Brewster LiNbO₃ Pockels cell operating in quarter-wave regime was 30% in closed state. Theoretically and experimentally was found, that for 25 mm long LiNbO₃ crystal voltage 1.5 kV is sufficient for Q-switching. With described Pockels cell was realized stable running Q-switched Er:YAG laser system. The generated giant pulse length and energy was 70 ns and 30 mJ, respectively.

Optically pumped, external-cavity, surface emitting semiconductor lasers (also known as optically pumped semiconductor lasers, OPS lasers, and vertical external cavity surface emitting lasers, VECSELs) generate near-diffraction limited beams from low brightness diode-array pumps. We have demonstrated 30 W cw at 980 nm and 15 W cw at 488 nm in a single spatial mode from these emitters and believe they can be scaled to > 100 W. Potential applications we have explored for such devices include wavelength conversion, spectral and spatial brightness conversion.

The principle ideas of the thin disk laser design will be illustrated and the advantages for operating different laser materials will be explained. The results for cw- and q-switched operation as well as for amplification of short (ns) and ultra-short (ps, fs) pulses demonstrate the potential of the thin disk laser design. The scaling laws for this laser design show that the power limit for cw-operation is far beyond 10 kW for one single disk and the energy limit is higher than 1 J from one disk in pulsed operation. Also the applicability of the thin disk laser concept to optically pumped semiconductor structures will be discussed. When pumping directly into the quantum wells the energy defect between pump- and laser photon can be smaller than 5% thus reducing the waste heat generated inside the semiconductor structure. First results demonstrate the potential of this new concept. Finally, a short overview of the industrial realization of the thin disk laser technology will be given.