Abstract: A laser device includes an outcoupling mirror, a laser medium, a phase-conjugate mirror based on stimulated Brillouin scattering, and an end mirror all arranged along an optical axis of the laser device. A controllable modulator is positioned between the phase-conjugate mirror and the end mirror. The outcoupling mirror and the end mirror form a start cavity. The outcoupling mirror and the phase-conjugate mirror form a main cavity.

Abstract: A laser amplification arrangement comprising a laser medium for producing an amplified laser emission as output signal from a useful signal to be amplified and a pump source has a switching component for coupling the useful signal into the laser medium. Laser medium and switching component are formed and arranged so that a division of an input signal (ES) into the useful signal and a background signal is effected, the background signal being passed through the laser medium at a time immediately before and/or after the coupling-in of the useful signal to be amplified.

Abstract: A semiconductor laser light source emits a laser beam for pumping. An optical resonator includes a solid laser crystal to be excited by the incident of a laser beam to oscillate a fundamental wave and a pair of fundamental wave reflective coats arranged at the opposite sides of the solid laser crystal. A wavelength conversion element converts the fundamental wave into a plurality of harmonics. The wavelength conversion element is so arranged in the optical resonator that the optical axis of at least one of the plurality of harmonics, generated in the optical resonator is made different from that of the fundamental wave and the at least one harmonic whose optical axis is made different is output substantially in the same direction as the other harmonic. By this construction, it is possible to stabilize a harmonic output and utilize a plurality of harmonics without increasing the number of parts.

Abstract: A linear-cavity all-fiber-based ultra short pulse laser system is provided. The all-fiber-based ultra short pulse laser system includes a pulse pump light source, a gain fiber, a first fiber signal pump combining unit, a broadband optical isolator, a fiber saturable absorber, an assistant light source, a second fiber signal pump combining unit, and a light coupling output. A broadband amplified spontaneous emission, emitted by the first fiber signal pump combining unit, which is connected to the pulse pump light source and the gain fiber, passes through the broadband optical isolator. The second fiber signal pump combining unit is connected to the assistant light source and the fiber saturable absorber. An ASE signal actively provides passive mode locking of the cavity, and the light coupling output partially outputs the laser. A dispersion fiber controls the temporal width.

Abstract: A laser head generating ultrashort pulses is integrated with an active beam steering device in the head. Direct linkage with an application system by means of an adequate interface protocol enables the active device to be controlled directly by the application system.

Abstract: A semiconductor light emitting device includes a pump light source, a gain structure, and an out-coupling mirror. The gain structure is comprised of InGaN layers that have resonant excitation absorption at the pump wavelength. Light from the pump light source causes the gain structure to emit light, which is reflected by the out-coupling mirror back to the gain structure. A distributed Bragg reflector causes internal reflection within the gain structure. The out-coupling mirror permits light having sufficient energy to pass therethrough for use external to the device. A frequency doubling structure may be disposed between the gain structure and the out-coupling mirror. Output wavelengths in the deep-UV spectrum may be achieved.

Abstract: A laser configuration producing up to 100's of Watts of output is provided, based on a solid-state gain medium, a source of pump energy which is detuned from the maximum absorption wavelength for the gain medium, and optics arranged to deliver the pump energy through an end of the gain medium to propagate along the length of the gain medium. The length of the gain medium and the doping concentration in the gain medium are sufficient the absorption length is on the order of 10's of millimeters, and more than ? of the length, and that 90 percent or more of the pump energy is absorbed within two or fewer passes of the gain medium. A pump energy source that supplies 100 Watts to 1000 Watts or more.

Abstract: Provided are an apparatus and a method for converting laser energy, characterized by employing an optical parametric oscillator for converting light of a green laser wavelength into light of a blue or red laser wavelength via a phase matching structure, by means of a non-linear optical crystal having a one-dimensional quasi-phase matching structure with a single grating period under appropriately-controlled temperature conditions. The non-linear optical crystal with the single grating period facilitates optical parametric oscillation and second harmonic generation to thereby enable green-to-blue wavelength conversion with a slope efficiency greater than 20%. Under 400 mW green light pump laser action, a periodically poled LiTaO3 crystal with a crystal length of 15 mm and without a resistant reflective plating film on its end face is capable of outputting a blue light laser beam of 56 mW.

Abstract: A laser apparatus with all optical-fiber includes a plurality of pumping light sources in different wave bands and an optical-fiber laser system. The optical-fiber laser system includes an optical fiber at least doped with erbium (Er) element and doped with or not doped with ytterbium (Yb) element according to a need. The optical-fiber laser system outputs a laser light through the pumping light source.

Abstract: Systems and methods for high brightness, improved phase characteristics laser diodes.

Abstract: Diode pumped, ytterbium doped glass or glass ceramic lasers are provided. A laser source is provided comprising an optical pump, a glass or glass ceramic gain media, a wavelength conversion device, and an output filter. The gain media comprises a ytterbium doped glass or a ytterbium doped glass ceramic gain media and is characterized by an absorption spectrum comprising a maximum absorption peak and a sub-maximum absorption peak, each disposed along distinct wavelength portions of the absorption spectrum of the gain media. The optical pump and the gain media are configured such that the pump wavelength ? is more closely aligned with the sub-maximum absorption peak of the gain media than the maximum absorption peak of the gain media. Additional embodiments are disclosed and claimed.

Abstract: Output beam from laser diode bar (1) has divergence around 40 degrees along the fast axis and around 12 degrees along the slow one. The quality of such a beam along the fast axis is good and fast axis collimating lens (FAC) (2) can compensate its high divergence down to 0.5-1 degrees. In the direction of the slow axis the beam from the laser diode bar is focused by cylindrical lens (3) onto the pumping face of laser active medium (5). The pumping face is wider than the pumping spot on it to ensure efficient collection of pumping light. Laser active medium has two parallel faces which form a waveguide for the pumping light. As a result, the pumping light is confined within the waveguide along the slow-axis direction and collimated (near parallel) in the fast-axis direction. Therefore, length of the pump volume (6) can be as long as the laser element itself.

Abstract: The present invention relates to an optical element for converting light of prescribed wavelength emitted from a light source into light of wavelength different from the prescribed wavelength for outputting. A first crystal part (20) and a second crystal part (21) having respective surfaces opposed to each other whose coefficients of linear expansion are different by 5 ppm or more are optically polished so that the surfaces opposed to each other include crystallographic axes. An acrylic adhesive whose glass transition point is 75° C. or lower is applied to the adhesive surface of the first crystal part (20) or the second crystal part (21) to stick the first crystal part (20) and the second crystal part (21) to each other. The adhesive is irradiated with light to cure the adhesive and form an adhesive layer (22) having a refractive index of 1.52 or lower. Then, the first crystal part and the second crystal part stuck to each other are cut into a desired size to form the optical element.

Abstract: A surface emitting semiconductor laser includes a semiconductor chip (1), which emits radiation (12) and contains a first resonator mirror (3). A second resonator mirror (6) is arranged outside the semiconductor chip (1). The first resonator mirror (3) and the second resonator mirror (6) form a laser resonator for the radiation (12) emitted by the semiconductor chip (1). The laser resonator contains an interference filter (9, 17), which is formed from an interference layer system comprising a plurality of dielectric layers.

Abstract: A laser head generating ultrashort pulses is integrated with an active beam steering device in the head. Direct linkage with an application system by means of an adequate interface protocol enables the active device to be controlled directly by the application system.

Abstract: Methods and systems for hybrid gain guiding in laser resonators that combines the features of gain guiding and fiber or other types of lasers into a single system. Hybrid gain guiding in laser resonators is not limited to conventional fiber lasers. Any type of gain guided fiber, index guided or anti-guided, is used as an intracavity element to induce loss on high order modes in an otherwise multimode laser system. The gain guided element contributes little gain to the laser oscillator but allows only the lowest order mode to transmit without loss. When the gain guiding fiber length is selected so the loss for a particular cavity mode is greater than the gain, the cavity mode does not lase. Since the gain guiding fiber induces loss for all laser modes other than the lowest order mode it makes sure that the mode one higher than the lowest order mode does not lase and as a result, no other cavity modes lase.

Abstract: The present invention discloses a laser light source for implementing pulsed oscillation of laser light, which has a laser cavity in which a laser medium for generating emitted light with supply of excitation energy is placed on a resonance path; an excitation device for continuously supplying excitation energy to the laser medium; a monitor part for monitoring a power of light extracted at a middle point of the path of the cavity from the laser medium in accordance with the supply of the excitation energy by the excitation device; a Q-switch for modulating a cavity loss of the laser cavity; and a control part for performing such control as to stabilize a peak power or an energy of laser light pulses outputted in a state in which the cavity loss of the laser cavity is set at a second predetermined loss for oscillation of high-power pulses, based on the power of the emitted light monitored by the monitor part in a state in which the cavity loss of the laser cavity is set at a first predetermined loss for non-o

Abstract: The present invention describes an optically end-pumped laser gain module, comprising a gain medium which is pumped by a light beam that has a larger size on the input face of the medium than on its output face.

Abstract: A semiconductor laser excitation solid laser control device 1A according to the present invention is a control device for stabilizing a light quantity of an output light LO of a semiconductor laser excitation solid laser 2. The control device 1A comprises: a beam splitter 11A for branching a laser light emitted from the semiconductor laser excitation solid laser 2 into the output light LO and a control light LC; a light reception element 12 for detecting the light quantity of the control light LC branched by the beam splitter 11A; and control means 13 for controlling the light quantity of the laser light emitted from the semiconductor laser excitation solid laser 2 so that the light quantity detected by the light reception element 12 will be constant. The beam splitter 11A has a transmittance and a reflectivity not depending on the polarization characteristic of the laser light.

Abstract: A laser assembly and method of operating the assembly are described in which a pump beam is directed through an end-pumped solid-state laser gain medium four or more times. The pump beam is directed at a slight angle through a first end of the medium, reflects off the inner surface of the second, opposite end (to form a “V”), and then reflected by an external or integrated mirror back through the first end and off the inner surface of the opposite end again (back through the “V”).

Abstract: A method and apparatus may comprise a line narrowed pulsed excimer or molecular fluorine gas discharge laser system which may comprise a seed laser oscillator producing an output comprising a laser output light beam of pulses which may comprise a first gas discharge excimer or molecular fluorine laser chamber; a line narrowing module within a first oscillator cavity; a laser amplification stage containing an amplifying gain medium in a second gas discharge excimer or molecular fluorine laser chamber receiving the output of the seed laser oscillator and amplifying the output of the seed laser oscillator to form a laser system output comprising a laser output light beam of pulses, which may comprise a ring power amplification stage.

Abstract: An active element for a laser source, the active element comprising an elongated bar with a reflective lateral surface, doped to be able to absorb at least a pumping beam being propagated at least approximately longitudinally in the bar in order to amplify at least a laser radiation also being propagated longitudinally; and a jacket in contact with the lateral surface of the bar and presenting a refractive index smaller than that of the bar, in the reflective lateral surface of the bar, there is at least one dull-ground diffusing zone able to interrupt the paths of spurious laser modes being propagated in the bar by total internal reflections on the lateral surface.

Abstract: A spatial coupling provided between an amplified-light waveguide and an output-light waveguide includes a wavelength selecting element that selectively transmits a light having a desired wavelength band out of a spontaneous emission light generated in the amplified-light waveguide and a lens unit that couples the spontaneous emission light to the wavelength selecting unit. An input-side light reflecting unit provided between a semiconductor pumping laser and the amplified-light waveguide and an output-side light reflecting unit formed on an output side of the spatial coupling unit form a laser resonator.

Abstract: An optically pumped, surface-emitting semiconductor laser having a mode-selective apparatus (7) which is intended for suppression of predeterminable, higher resonator modes of the semiconductor laser. The mode-selective apparatus is arranged in the beam path of a pump beam source (2) of the surface-emitting semiconductor laser.

Abstract: A laser system and method. The inventive laser includes an annular gain medium; a source of pump energy; and an arrangement for concentrating energy from the source on the gain medium. In a more specific implementation, a mechanism is included for rotating the gain medium to effect extraction of pump energy and cooling. In the illustrative embodiment, the pump source is a diode array. Energy from the array is coupled to the medium via an array of optical fibers. The outputs of the fibers are input to a concentrator that directs the pump energy onto a pump region of the medium. In the best mode, plural disks of gain media are arranged in an offset manner to provide a single resonator architecture. First and second mirrors are added to complete the resonator. In accordance with the inventive teachings, a method for pumping and cooling a laser is taught.

Abstract: In a laser device, a crystal array includes a laser gain crystal and an optically non-linear frequency conversion crystal. A pump source couples at least two mutually spatially separated pump beams into the crystal array. Between two pump beams, a saw kerf of the crystal array extends parallel to the pump beams.

Abstract: A surface emitting laser (SEL) with an integrated absorber. A lower mirror and an output coupler define a laser cavity of the SEL. A monolithic gain structure positioned in the laser cavity includes a gain region and an absorber, wherein a saturation fluence of the absorber is less than a saturation fluence of the gain region.

Abstract: Methods, systems and devices for a waveguide pumping gain guided index antiguided fiber laser having a fiber selected for a refractive index crossover at a wavelength between a pump wavelength and a laser emission wavelength. A waveguide pumping system pumps a light having a pump wavelength into the fiber allowing a laser light to be captured by a gain guided process in the core while the pump light, propagating in the cladding is coupled to the core. The fiber selection includes selecting a fiber with a cladding material having a refractive index less than a core material refractive index for a pump wavelength and a core refractive index at the laser emission wavelength is less than the cladding refractive index at the same laser emission wavelength to allow the pump light to propagate through the cladding as a conventional wave guided fiber laser, white the laser emission is captured within the core as an index antiguided, gain guided wave.

Abstract: The invention is directed to an optically pumped surface-emitting semiconductor laser device having at least one radiation-generating quantum well structure and at least one pump radiation source for optically pumping the quantum well structure, whereby the pump radiation source comprises an edge-emitting semiconductor structure. The radiation-generating quantum well structure and the edge-emitting semiconductor structure are epitaxially grown on a common substrate. A very efficient and uniform optical pumping of the radiation-generating quantum well structure is advantageously possible with this monolithically produced semiconductor laser device. Methods for manufacturing inventive semiconductor laser devices are also specified.

Abstract: Provided is a pump laser integrated vertical external cavity surface emitting laser (VECSEL). The VECSEL may include a surface emitting laser unit including a first active layer having a multiple quantum well structure emitting light having a first wavelength, a reflective layer may be formed on the first active layer, and an external mirror may be disposed opposite to a lower surface of the first active layer and defining a cavity resonator together with the reflective layer. A pump laser unit may be formed on a part of the surface emitting laser unit and may have a perpendicular light emissive surface emitting a pump beam having a second wavelength for exciting the first active layer. A beam reflector may be formed on the light emissive surface of the pump laser unit and reflecta pump beam that is incident from the pump laser unit to the first active layer.

Abstract: A laser pumped tunable laser system is disclosed directed to achieving tunable outputs with high wall plug efficiencies. In particular, green laser pumped alexandrite lasers are discussed—both pulsed and CW—where the wall plug efficiencies of greater than 2% can be achieved using practical, commercially available pump lasers. In alternative approaches, frequency converted tunable radiation in the UV is achieved with high efficiency from compact, high beam quality devices.

Abstract: An optical element for homogenizing and, possibly, concentrating the output from high-power two-dimensional semiconductor laser arrays, which has the basic shape of a convex-flat cylindrical lens with a facet cut into the convex surface for each individual semiconductor laser bar.

Abstract: A pumping system for a laser source includes a pump diode that emits a pump beam having a central wavelength that varies with temperature. A selective mirror having a plurality of spectral reflectivity peaks, corresponding to a plurality of predetermined wavelengths, locks the operation of the pump diode onto one of the predetermined wavelengths in accordance with temperature.

Abstract: A method for increasing the efficiency of generating lasers by pumping two separate wavelengths into an erbium-based medium to populate the 4I11/2 state and depopulate the 4I13/2 state. A first excitation wavelength region is located between approximately 955 nm to approximately 1100 nm. The second excitation wavelength region is located between approximately 1600 nm to approximately 1850 nm. This multi-wavelength pumping scheme may be operated in continuous wave or quasi-continuous wave mode.

Abstract: A laser pumped tunable laser system is disclosed directed to achieving tunable outputs with high wall plug efficiencies. In particular, green laser pumped alexandrite lasers are discussed—both pulsed and CW—wherein the wall plug efficiencies of greater than 2% can be achieved using practical, commercially available pump lasers. In alternative approaches, frequency converted tunable radiation in the UV is achieved with high efficiency from compact, high beam quality devices.

Abstract: The invention is in the field of laser radiation generation in bands II and III, and relates to a device for generating laser radiation in the infrared having means for modifying the amplified-radiation frequency and using the Raman effect, characterized by additionally having at least one diode able to emit laser radiation in the 1.8-2.1 ?m frequency range, at least one current generator able to generate current levels at an adjustable repetition rate, means for supplying said current levels to said diode, and means for amplifying the laser radiation emitted by said diode and comprised of at least one fiber doped with an ion having laser activity in the diode emission range.

Abstract: Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

Abstract: A fiber laser cavity that provides a new pulse shaping and spectral shaping technique is disclosed in this invention to achieve the purpose of resolving the difficulties arising from the issues related to Q-switched solid state lasers. The laser system achieves high repetition rate (1 kHz-100 kHz) and high pulse-to-pulse energy stability with small timing jitter of the laser pulses and scalable to the Joule pulse energy level. The laser system of this invention employs new approach with a hybrid fiber/waveguide master Oscillator-High Power Amplifier (MOPA) laser system in combination with the pulse shaping technology that allows not only to scale the fiber laser pulse energy to the multi-Joule level with high pulse-to-pulse energy stability but also achieve precise control of laser pulse timing jitter in a scale of <100 ps that is at least 5 to 10 time more accurate than for Q-switched systems where the same parameter reaches 500-1000 ps range.

Abstract: A vertical external cavity surface emitting laser (VECSEL) is provided, in which the incident loss of a pumping beam is reduced. The VECSEL device comprising: a transparent substrate; an optical pump radiating a pumping beam onto a first surface of the transparent substrate; a first anti-reflection coating (ARC) layer formed of a first light-transmitting insulating material on a second surface of the transparent substrate to reduce loss of the pumping beam; a distributed Bragg reflector (DBR) layer formed on the first ARC layer; a periodic gain layer formed on the DBR layer; and an external cavity mirror facing the periodic gain layer.

Abstract: The aim of the invention is to obtain a laser system with the highest possible power that operates as stably as possible. This object is achieved in the case of a laser system by the laser radiation field passing through at least two laser-active solid bodies of identical material disposed one following the other in the direction of its beam axis, by the pumping radiation guide being formed in such a way that it feeds into each of the solid bodies the first partial radiation field via one end face and the second partial radiation field via the other end face and by the pumping radiation guide being formed in such a way that a pumping power fed into each of the at least two solid bodies by the two partial radiation fields can be adjusted in such a way that the effects on the laser radiation field of thermal lenses produced by the pumping power in each of the at least two solid bodies are substantially identical.

Abstract: Various methods, systems, and apparatuses are described in which a light source (101) capable of lasing is wavelength locked by an injected light signal. The light source (101) capable of lasing, such as a Fabry-Perot laser diode, may have antireflective coating on one or more facets of the light source (101) capable of lasing. The light source (101) capable of lasing receives a spectral slice of a light signal from a broadband light source (113) to wavelength lock the output wavelength of the light source (101) capable of lasing within the bandwidth of the injected light signal. A current pump (141) may bias the light source (101) capable of lasing to operate as a reflective regenerate semiconductor optical amplifier so that the injected light is reflected back out a front facet after being amplified and wavelength locked.

Abstract: Provided is a vertical external cavity surface emitting laser (VECSEL) in which a pump laser is integrated with the rest of the VECSEL as a single body. The VECSEL includes: a first active layer that has a quantum well structure and generates light with a first wavelength; a reflection layer formed on a first surface of the first active layer; an external mirror that is separated by a predetermined distance from a second surface of the first active layer, transmits a portion of light generated by the first active layer to the outside, and reflects the rest of the light generated by the first active layer to be absorbed by the first active layer; and a pump laser disposed on the reflection layer as a single body to provide light with a second wavelength which is shorter than the first wavelength to the first active layer for optical pumping.

Abstract: The present invention relates to an optically pumped waveguide laser (2) comprising a waveguide with an optical propagation layer (3, 4) and two resonator mirrors (6, 7). The propagation layer (3, 4) consists of a gain medium at least along a section of said waveguide, said gain medium allowing up-conversion or down-conversion of incident pump light. One of the resonator mirrors is at least partially transparent to the pump light so as to allow end-pumping of the waveguide laser through a first end face (8) of the waveguide. The propagation layer (3, 4) has a geometrical width which is reduced in a first section of the waveguide, starting from the first end face (8) towards a second end face (9), thereby increasing an energy density of the incident pump light when propagating in the first section towards the second end face (9).

Abstract: An apparatus for optically pumping a laser-active solid body with pumping light coupled into the solid body through an end surface of the solid body is disclosed. The apparatus includes a laser-active solid body including an end surface though which pumping light is coupled into the solid body and a lateral surface through which pumping light exits the solid body, a reflector surrounding the laser-active solid body at a distance from the lateral surface of the solid body for reflecting light that exists the solid body back towards the solid body, and a surface for diffusing light that is coupled into the solid body through the end surface of the solid body and that exits the solid body through the lateral surface. The surface is selected from the group consisting of the lateral surface and a surface of the reflector.

Abstract: A laser apparatus for producing a laser light beam can include a gain medium; a pump light source to provide a pump light beam to the gain medium; a first reflector disposed between the first gain medium and the first pump light source and spaced apart from a gain portion of the first gain medium; a second reflector; and an output coupler. The first reflector is substantially reflective to the laser light beam and substantially transmissive to the pump light beam. The first and second reflectors and the output coupler define a folded beam path having a first portion and a second portion. The first portion of the beam path extends from the first reflector to the second reflector through the gain medium and the second portion of the beam path extends from the first reflector to the output coupler through the gain medium. The first and second beam paths define, within the gain medium, a non-zero folding angle.

Abstract: Systems and methods for optically pumping alkali-metal atoms using Coherence Population Trapping (CPT) resonances are disclosed. An illustrative push-pull optical pumping system for inducing CPT resonances in a resonance cell containing an admixture of alkali-metal atoms and one or more buffer gasses may include a laser assembly adapted to produce alternating orthogonally polarized light, and at least one DC current source adapted to output a constant-intensity carrier current signal for inducing laser emission from the laser assembly at a carrier wavelength of the alkali-metal atoms. An RF modulated signal outputted from an RF modulation source can be rectified, split, and phase-shifted for inducing a time-dependent polarization of the laser light that can be used to enhance CPT resonances.

Abstract: The invention provides an optical multiplexing device comprising: a plurality of optical sources with integrated collimators (31-37) whose output beams are combined by mirrors (41-47) or other beam deflecting elements, which combine the beams into a single composite beam diverging from a common origin point (30). This is done by arranging the mirrors (41-47) staggered at different distances from the origin point, and at different angles to each other taking accourt of the dependence of the beam divergence in far field on the distance from the origin point.

Abstract: A method for optically pumping a gain-medium with partially polarized or unpolarized pump-light having a wavelength at which that gain-medium has an absorption that is dependent on the polarization plane of the pump-light is disclosed. The pump-light is directed into the gain-medium. The strongest-absorbed polarization component of the pump-light is substantially absorbed and the weakest-absorbed polarization component is partially transmitted by the gain-medium. The polarization plane of the transmitted component is rotated through 90 degrees and the polarization-rotated pump-light is directed back into the gain-medium, wherein it is substantially absorbed.

Abstract: A laser system and method. The inventive laser includes an annular gain medium; a source of pump energy; and an arrangement for concentrating energy from the source on the gain medium. In a more specific implementation, a mechanism is included for rotating the gain medium to effect extraction of pump energy and cooling. In the illustrative embodiment, the pump source is a diode array. Energy from the array is coupled to the medium via an array of optical fibers. The outputs of the fibers are input to a concentrator that directs the pump energy onto a pump region of the medium. In the best mode, plural disks of gain media are arranged in an offset manner to provide a single resonator architecture. First and second mirrors are added to complete the resonator. In accordance with the inventive teachings, a method for pumping and cooling a laser is taught.

Abstract: A Ho:YAG crystal laser is disclosed which is doped with less than 2% holmium to reduce the lasing threshold and up-conversion, thereby increasing the operating efficiency of the laser. The laser does not need sensitizer ions so energy mismatches introduced by the sensitizer ions ale eliminated to the thereby increase the efficiency of the laser while minimizing detrimental thermal loading in the laser caused by up-conversion loss processes. The Ho:YAG crystal laser is directly pumped by a Thulium fiber laser at 1.9 ?m at the holmium 5I7 to 5I8 transition to produce an output at 2.1 ?m yielding a very low quantum defect. The laser is embodied as a thulium fiber laser pumped oscillator or an amplifier.