Abstract: Provided is a diode-pumped solid-state laser adapted for an intracavity sum-frequency mixing for generating a laser radiation of a visible wavelength range by performing a sum-frequency mixing of two laser inputs in a laser resonant cavity. A pair of laser resonators of two different wavelengths are formed along a common optical path and an intracavity sum-frequency mixing is conducted so as to obtain a laser radiation at a sum-frequency wavelength by placing a nonlinear optical crystal on this common optical path. By suitably selecting the properties of the reflective surfaces that form the laser resonators, a laser radiation of a relatively short wavelength range can be obtained even though the wavelength of the pumping laser beam is relatively long, and an extremely high conversion efficiency can be achieved.

Abstract: The present invention relates to a solid-state laser comprising: a) a semiconductor pump laser, b) a lens integrated on the surface of said semiconductor pump laser, c) a packaging material consisting essentially of a spin-on glass material, wherein the spin-on glass material is processable at a process temperature of less than 225° C., and d) a lasing material layer having a highly reflective coating in both sides. The invention also relates to a process for producing such a solid-state laser, which process comprises applying spin-on glass material onto semiconductor wafers having VCSEL pump lasers using different coating methods, such as spin coating, and curing the glass film layer at temperatures <225° C.

Abstract: A system for generating a powerful laser beam includes a first laser element and at least one additional laser element having a rear laser mirror, an output mirror that is 100% reflective at normal incidence and <5% reflective at an input beam angle, and laser material between the rear laser mirror and the output mirror. The system includes an injector, a reference laser beam source, an amplifier and phase conjugater, and a combiner.

Abstract: Co-doping the gain medium of a diode-pumped infrared laser to make the laser resistant to long-term degradation from high-intensity internal infrared radiation is disclosed. Co-doping the gain medium with ions such as Cr3+ and Ce3+ that make the gain medium resistant to external ionizing radiation solves problems of long-term degradation of the gain medium.

Abstract: The End Pumped Slab Laser Cavity incorporates all optical components required for a short-pulse laser. These optical components are ‘locked’ into alignment forming an optical laser cavity for diode laser or flash lamp pumping. The optical laser cavity never needs optical alignment after it is fabricated. The cavity is configured for optimal absorbtion for diode laser end-pumping over broad temperature ranges.

Abstract: A pump fiber is stripped of its cladding over the last section. This can occur by etching a coating off. The sheath is preferably etched off wedge-shaped. As a result thereof, the remaining pump power is eliminated into the environment. How much stray pump light still proceeds via the fiber core to the fiber exit can be monitored over a length of the fiber completely stripped of the protective sheath.

Abstract: Apparatus and method for stabilizing the wavelength of a tunable laser to a target wavelength, by correspondingly adjusting the electrooptical performance of the laser's gain medium, whereby to eliminate the frequency shift due to vibrational factors. The electrooptical performance of the laser's gain medium is adjusted, in the case of an electrically pumped laser, by changing the injection current used to pump the laser; and the electrical performance of the laser's gain medium is adjusted, in the case of an optically pumped laser, by changing the intensity of the pump laser used to energize the laser. The system is implemented with a feedback mechanism.

Abstract: An optical fiber amplifier module is disclosed which comprises a signal path located between a signal input and a signal output. A WDM coupler and an amplifying gain medium are disposed along the signal path. A pump laser is disposed out of the signal path in a manner that allows a pump signal from the pump laser to reflect off the WDM coupler and enter the signal path. An embodiment utilizing a second WDM coupler and a second pump laser is also disclosed.

Abstract: By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths.

Abstract: A diode pumped solid state laser using a laser diode bar or a stack of bars with cylindrical lenses is used to end pump a rectangular cross section solid state laser slab. The combination of lenses and polished slab surfaces provides overlap of the pump light with the laser mode combined with sufficient length of material to absorb all of the pump light to produce a compact, efficient laser source.

Abstract: A laser amplifier includes a gain medium of a glass fiber, a first exciting light source, a second exciting light source, and another first exciting light source. The gain medium of the glass fiber includes rare earth dopant in a host medium. Ions of the rare earth dopant has an energy level structure including a ground level and a pair of laser upper level and laser lower levels between which a stimulated transition is to be produced after production of a population inversion between the pair of laser upper and laser lower levels. The pair of laser upper and laser lower levels being higher than the ground level. The first exciting light source is coupled to the input side of the glass fiber for introducing first exciting light to the glass fiber to produce the population inversion.

Abstract: A Raman gain control method of controlling a Raman gain caused by simultaneous application of pump lights of a plurality of wavelengths to an optical fiber, which includes, based on a relation of a ratio coefficient which is a ratio of power of each pump light to total power of all the pump lights with the Raman gain, from a designated value of the Raman gain, calculating power of each pump light realizing the designated Raman gain within a designated wavelength range, and controlling power of each pump light applied to the optical fiber to apply each pump light at each power calculated.

Abstract: A laser includes an Nd:YVO4 crystal end-pumped with diode-laser light having a wavelength at which the absorption coefficient for Nd:YVO4 is less than about 0.35 (35%) of the absorption coefficient at 808 nm.

Abstract: An optical system has a diode pump source, and a gain media made of a material with an anisotropic absorption. The gain media is cut at an angle to produce substantially polarization-independent absorption of a pump beam. An optical coupler is positioned between the diode pump source and the gain media. The optical coupler produces a pump beam that has substantially equal amounts of pump power along any two orthogonal axis that are orthogonal to the pump beam in the gain medium. The wavelength range allowed for the pump source is extended.

Abstract: A laser system includes a laser diode with a low dimensional nanostructure, such as quantum dots or quantum wires, for emitting light over a wide range of wavelengths. An external cavity is used to generate laser light at a wavelength selected by a wavelength-selective element. The system provides a compact and efficient laser tunable over a wide range of wavelengths.

Abstract: This invention describes new developments in Sagnac Raman amplifiers and cascade lasers to improve their performance. The Raman amplifier bandwidth is broadened by using a broadband pump or by combining a cladding-pumped fiber laser with the Sagnac Raman cavity. The broader bandwidth is also obtained by eliminating the need for polarization controllers in the Sagnac cavity by using an all polarization maintaining configuration, or at least using loop mirrors that maintain polarization. The polarization maintaining cavities have the added benefit of being environmentally stable and appropriate for turn-key operation. The noise arising from sources such as double Rayleigh scattering is reduced by using the Sagnac cavity in combination with a polarization diversity pumping scheme, where the pump is split along two axes of the fiber. This also leads to gain for the signal that is independent of the signal polarization.

Abstract: An optical transmission equipment for use in an optical transmission system, having an optical amplifier (10A), comprising: a first optical doped fiber (1A); a second optical doped fiber (1B); a third optical doped fiber (1C); an optical isolator (6) of bringing loss in the optical signal, being provided between the first optical doped fiber and the second optical doped fiber; a dispersion compensator (7) being provided between the second optical doped fiber and the third optical doped fiber; and a pumping light source (2) being optically connected to so that the optical doped fibers (1A, 1B, 1C) are excited in common.

Abstract: A microchip laser arrangement is disclosed. The arrangement is operative to emit Q-switched laser pulses at 1.54 &mgr;m. The lasing medium of the laser arrangement is preferably comprised of Yb:Er-glass, and the Q-switch is comprised of a saturable absorber of cobalt doped spinel crystal. The lasing medium is preferably bonded to the absorber to form a monolithic body, upon the surface of which there are deposited dielectric stacks forming a resonant laser cavity. Pumping of the active medium is performed by means of an InGaAs laser diode emitting light at 0.97 &mgr;m, corresponding well with the absorption of the Yb:Er-glass material.

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: An apparatus for removing heat from a lasing medium of a solid-state laser assembly is provided that comprises a working fluid and at least one condensation surface defined by a housing in which at least a portion of the lasing medium is housed. The apparatus further comprises a coolant circuit and a wick disposed to distribute the working fluid in a liquid state over at least a portion of an outer surface of the lasing medium and to capture working fluid condensing upon the at least one condensation surface. During use, the wick distributes the working fluid in a liquid state over the at least a portion of the outer surface of the lasing medium. During contact with the at least a portion of the outer surface of the lasing medium, the working fluid evaporates and removes heat from the lasing medium. The working fluid in a vapor state contacts the at least one condensation surface, transfers heat to the at least one condensation surface, and condenses on the at least one condensation surface.

Abstract: The medical laser unit (1) includes at least one laser body (3) being made of laser material (4). A first type of a pump light source (11) is designed and arranged to continuously excite the laser material (4) and to generate continuous laser radiation (7). A second type of a pump light source (16) is designed and arranged to excite the laser material (4) by pulses and to generate pulsed laser radiation (7). A transmitting unit is designed and arranged to transmit the continuous laser radiation (7) and the pulsed laser radiation (7) to a surgical application site. More particularly, the medical laser unit (1) has two modes of operation, a first mode for cutting with continuous laser radiation (7) and a second mode for fragmenting with pulsed laser radiation (7) of short time and high power laser pulses.

Abstract: A multi-channel light source generator has a pumping laser source for generating a pumping laser having a predetermined wavelength, a multi-channel light source generating device for generating multi-channel light sources using the pumping laser, a light separating device for separating the pumping laser and the multi-channel light sources, a demultiplexing device for separating the multi-channel light sources into a plurality of individual light sources, an intensity adjusting device for adjusting an intensity of the individual light sources, and a multiplexing device for combining the individual light sources outputted from the intensity adjusting device.

Abstract: An object of the present invention is to prevent an increase of the degree of polarization of an output pumping light even if one of pumping light sources has a failure. Laser diodes (30a, 30b) are composed of FP-LDs made of InGaAsP to laser-oscillate at 1480 nm band. The outputs from the laser diodes (30a, 30b) enter a polarizing beam splitter (32) in orthogonal state of polarization and are combined there. The combined light by the polarizing beam splitter (32) enters a depolarizing element (34) and is depolarized there.

Abstract: An optical arrangement for direction dependent coupling out of light comprises a first and a second polarization converter each for converting the state of polarization of light received in a predetermined way. A polarization dependent coupling device is adapted for coupling out a portion of the light received, whereby the ratio of the coupled out portion substantially depends on the state of polarization of the light received. The polarization dependent coupling device is arranged between the first and the second polarization converters, and the optical arrangement receives from different sides light beams propagating in different directions. The characteristics of the first and the second polarization converters are adapted such that the polarization dependent coupling device receives light beams propagating with different states of polarization in the different directions.

Abstract: A semiconductor laser apparatus comprises a pumping beam source and a surface emission type of semiconductor device. The pumping beam source is constituted of a semiconductor laser device, in which a composition selected from the group consisting of InGaN and GaN is employed in an active layer. The surface emission type of semiconductor device comprises a substrate, and an active layer, which is constituted of a composition selected from the group consisting of InGaAlP and InGaP and is provided on the substrate. The surface emission type of semiconductor device is pumped by the pumping beam source to produce a laser beam. The semiconductor laser apparatus produces the laser beam having a wavelength of a red region or an ultraviolet region and undergoes oscillation in a fundamental mode with a high reliability and a high efficiency and up to a high output power.

Abstract: A double pumped Raman amplifier is provided that increases gain over a same length of gain fiber without significantly increasing a percentage of noise. The amplifier may include a source of pump light coupled to the output end of a coil of Raman gain fiber, and a reflector coupled to the input end of the coil which may be either a mirror, or a fiber Bragg grating. Alternatively, a beam splitter may be connected to the source of pump light and the resulting split output may be coupled to both the input and output ends of the gain fiber. The increase in amplification efficiency allows the optical fiber used in components such as dispersion compensating modules to also be used as Raman gain fiber in such amplifiers.

Abstract: The invention relates to an optical fiber amplifier device with an optical signal input and output with first piece of amplifying fiber doped with lanthanide in a double-clad structure, a second piece of amplifying fiber doped with lanthanide in a ring structure and lasers for pumping the two fiber pieces with at least one pump module.

Abstract: An optical transmission equipment for use in an optical transmission system, having an optical amplifier (10A), comprising: a first optical doped fiber (1A); a second optical doped fiber (1B); a third optical doped fiber (1C); an optical isolator (6) of bringing loss in the optical signal, being provided between the first optical doped fiber and the second optical doped fiber; a dispersion compensator (7) being provided between the second optical doped fiber and the third optical doped fiber; and a pumping light source (2) being optically connected to so that the optical doped fibers (1A, 1B, 1C) are excited in common.

Abstract: In a diode-pumped laser amplifier the inventive object is to increase the tolerance of the amplifier arrangement relative to variations of the input parameters significantly, so that fine-tuning is no longer necessary for guaranteeing the stability of the amplifier. Into a laser-active solid-state medium where a thermal lens of a strength which is different in orthogonal planes is generated in consequence of the irradiated pump radiation, a laser beam to be amplified is directed into the laser-active solid-state medium while being focused in the plane with a strong thermal lens, wherein a beam waist that is being generated lies in the area of the thermal lens. The laser amplifier can be used for amplifying the radiation of an oscillator.

Abstract: A laser emitting apparatus includes an incoherent light-emitting device having a light-emitting layer wherein an electric field is applied across the light-emitting layer to produce light which is transmitted out of the incoherent light-emitting device and a vertical laser cavity structure disposed to receive light transmitted from the incoherent light-emitting device and produce laser light.

Abstract: A chirp signal source includes first and second lasers formed on a solid-state chip or substrate. Each of the lasers has a resonator or cavity which incorporates or includes electrooptic material which changes refractive index in response to an electric field. The lasers are pumped, and the resulting laser beams are coupled to a light-to-electric converter which combines the light beams to generate an electrical difference frequency. The change in refractive index allows the lasers to be swept or chin,ed at a much higher rate than thermal or piezoelectrically operated lasers. This structure has the advantages of tending to reduce temperature effects on the difference frequency. It has the further advantage of a high sweep rate, which can be used to improve the signal-to-noise ratio. A radar or lidar ranging system according to an aspect of the invention uses multiple solid-state lasers, which are thermally coupled together.

Abstract: A laser crystal is formed on a substrate in a solid-state laser device. The laser crystal oscillates laser beam from a second end face when an excitation beam is projected to a first end face. An excitation beam emission element emitting the excitation beam is provided for the solid-state laser device. A waveguide path is formed on the substrate. The excitation beam is transmitted through the waveguide path. The waveguide path has a first end portion on which the excitation beam emitted by the excitation beam emission element impinges and a second end portion which opposes the first end face of the laser crystal. The excitation beam is emitted from the second end portion.

Abstract: A laser beam generation apparatus includes a solid state laser medium having first and second optically polished planes provided opposed with each other to allow a laser beam to be pumped to pass out of one of the first and second optically polished planes. At least one third optical polished plane which is different from the first and second optically polished planes is also provided. A pumping beam source emits a pumping light beam to pump the laser medium and impinges the pumping light source to be incident on the at least one third optically polished plane. Further, the pumping laser beam is provided at an incident angle substantially equal to the Brewster angle.

Abstract: Internal combustion engine with at least one cylinder, in which the combustion of a homogeneous air/fuel mixture compressed in the cylinder by a piston is initiated by a time-controlled external ignition, the air/fuel ratio of the air/fuel mixture in the combustion chamber (25) being greater than 1.9 and, for the time-controlled external ignition, at least one laser light source (10), at least one optical transmission apparatus (11) and at least one coupling optic (12) for the focussing of laser light into a combustion chamber (25) being provided.

Abstract: An apparatus and method are described for exploiting almost the full almost 25TH% of bandwidth available in the low-loss window in optical fibers (from 1430 nm-1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.

Abstract: A laser apparatus is described having multiple modes of operation using intracavity optical switching within a laser resonator. The laser resonator has a solid state gain medium and one or more optical switches located between a pair of end reflectors. The pump for the gain medium has controlled duration to allow varying the pumping energy and pulse repetition rate. The laser has a Q-switched mode for generating energy from the laser resonator at a fixed level of outcoupling when the laser pump is operated to produce a range of predetermined pulse, rates and durations. The laser also has a cavity dumped mode of operation in which the laser pump is operated to produce a second range of predetermined higher pulse repetition rates and shorter pulse durations so that the pulse energy, rate and duration are selected by first Q-switching with essentially no outcoupling and then rapidly cavity dumping all the optical energy in the resonator.

Abstract: An optical fiber amplifier module is disclosed which comprises a signal path locatee between a signal input and a signal output. A WDM coupler and an amplifying gain medium are disposed along the signal path. A pump laser is disposed out of the signal path in a manner that allows a pump signal from the pump laser to reflect off the WDM coupler and enter the signal path. An embodiment utilizing a second WDM coupler and a second pump laser is also disclosed.

Abstract: A diode-laser side-pumped solid-state laser device (SSLD) has a cylindrical laser rod, a cooling tube, and a cylindrical mirror member having an inner mirror surface and a plurality of openings therein for introducing pumping laser. The laser rod receives the pumping laser, absorbs a portion of the pumping laser, and passes and focus the remaining portion of the pumping laser at a focal point disposed on the mirror surface. Substantially all the remaining portion of the pumping laser is reflected to be received and absorbed by the laser rod.

Abstract: In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In a third embodiment, alternating short and long pulses of light from the excitation light source are directed into the ignitor laser. Each of the embodiments of the invention can be multiplexed so as to provide laser light energy sequentially to more than one ignitor laser.

Abstract: Many longitudinally pumped miniature lasers (single-frequency Nd:YAG microchip lasers and Q-switched microchip lasers) are sufficiently short that only a small fraction of the incident pump light is absorbed as it passes through the gain medium. The efficiency of such a laser is improved when the output face of the laser is coated to reflect the pump light, thereby allowing double-pass absorption of the light within the gain medium. The total absorption may still be small, however. Additionally, the divergence of typical pump sources (diode lasers or optical fibers) is large enough that there is often poor overlap between the reflected pump light and the oscillating mode, and the efficiency of the device is not significantly enhanced. If the output face of the miniature laser is coated to be highly transmitting to the pump radiation, the transmitted pump light can be collected with a lens and focused in to an amplifying medium (Nd:YVO4).

Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.

Abstract: A diode pumped solid state laser using a laser diode bar or a stack of bars with cylindrical lenses is used to end pump a rectangular cross section solid state laser slab. The combination of lenses and polished slab surfaces provides overlap of the pump light with the laser mode combined with sufficient length of material to absorb all of the pump light to produce a compact, efficient laser source.

Abstract: An optical transmission equipment for use in an optical transmission system, having an optical amplifier (10A), comprising: a first optical doped fiber (1A); a second optical doped fiber (1B); a third optical doped fiber (1C); an optical isolator (6) of bringing loss in the optical signal, being provided between the first optical doped fiber and the second optical doped fiber; a dispersion compensator (7) being provided between the second optical doped fiber and the third optical doped fiber; and a pumping light source (2) being optically connected to so that the optical doped fibers (1A, 1B, 1C) are excited in common.

Abstract: A laser gain medium having a layered coating on at least certain surfaces of the laser gain medium. The layered coating having a reflective inner material and an absorptive scattering outside material.

Abstract: An apparatus and method for coupling an array of light beams extending predominantly in one direction into an output port. The light beams are rearranged into a desired shape which extends more equally along two directions than does incident array of light beams. The operation of the rearranging is wavelength insensitive. The rearranged light beams are focused onto the output port. For output ports having a small interface, the focal length of a lens focusing the rearranged light beams to the output port should be as short as possible.

Abstract: In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In two embodiments the beam from the excitation light source is split with a portion of it going to the ignitor laser and a second portion of it being combined with either the first portion after a delay before injection into the ignitor laser or combined with the output of the ignitor laser. In another embodiment alternating short and long pulses of light from the excitation light source are directed into the ignitor laser.

Abstract: A sub-nanosecond passively Q-switched microchip laser is disclosed. It combines an optically pumped, passively Q-switched, high-frequency, microchip laser producing short pulses with an optically end-pumped amplifier producing high small-signal gain while pumped at low power. The microchip laser for emitting pulsed laser radiation is a monolithic body comprising two reflective elements defining an optical resonator for laser radiation, a laser gain medium, e.g., Nd:YAG, and a saturable absorber medium, e.g., Cr4+:YAG placed inside said resonator. The optical amplifier stage for amplifying the laser radiation comprises an amplifying medium, e.g., Nd:YVO4. The microchip laser and the amplifier are optically end-pumped, preferably by high-brightness diodes. This entirely passive laser system directly produces &mgr;J pulses at repetition rates of about 45 kHz.

Abstract: A slab laser includes a laser-resonator and a plurality of generally-triangular prismatic slabs of a solid-state gain-medium located in the resonator. The prismatic slabs are cooperatively arranged such that laser-light circulating in the laser-resonator follows a convoluted path through the prismatic slabs. Each of the prismatic slabs changes the direction of the convoluted path at least once by about one-hundred-eighty degrees.

Abstract: Visible light-emitting-diodes (LEDs) are inexpensive, provide emissions in many wavelengths and are powerful enough to pump solid state laser rods. The LED light is directed to the laser rod (laser gain element). The LED wavelength chosen matches the absorption spectrum of a transition element contained in the laser rod. It is know that the absorption bandwidths of these elements are typically very large. Besides a single LED, an array of LEDs may be used. Either of these arrangements may be imaged on the laser rod or fiber-coupled to the rod. A laser system that is pumped by one or more LEDs provides a low cost, relatively low power laser system. A low cost, higher powered, pulsed laser system is possible by pulsed LED operation. Thus it is possible to exceed the pump power threshold for a given laser by using a relatively small number of LEDs.

Abstract: The invention relates to a microlaser cavity (10) having: a solid active medium (2) emitting at least in a wavelength range between 1.5 and 1.6 &mgr;m, and a saturable absorber (4) of formula CaF2:Co2+ or MgF2:Co2+ or SrF2:Co2+ or BaF2:Co2+ or La0.9Mg0.5-xCoxAl11.433O19 or YalO3:Co2+ (or YAl5-2xCoxSixO3 YAl(1-2x)CoxSixO3) or Y3Al5-x-yGaxScyO12:Co2+ (or -3Al5-x-y2zGaxScyCozSizO12 Y3Al5-x-y-2zGaxScyCozSizO12) or Y3-xLuxAl5O12:Co2+ (or Y3-xLuxAl5-2yCoySiyO3) or Sr1-xMgxLayAl12-yO12:Co2+ (or Sr1-xMgx-yCoyLazAl12-zO12, with 0<y<x) Sr1-xLaxMgxAl12-xO19:Co2+ (or Sr1-xLaxMgx-yCoyAl12-xO19 , with 0<y<x).