Abstract: A crystalline material for optically pumped solid state lasers has the chemical composition of M3RE1-x Ybx(BO3)3, where M is selected from the group Mg, Ca, Sr, Ba, and Ra, optionally replaced at least partially with another element from this group, RE is selected from the group Sc, Y, Lu, and Y partially replaced with Lu, and x is greater than or equal to 0 and less than or equal to 1. The material is useful for preparing lasers having high average initial power and short pulse duration, and has flat amplification and fluorescence spectra, high thermal conductivity and a large emission cross-section.

Abstract: Non-linear single crystal obtained by crystallization of a congruent molten composition of general formula:M.sub.4 LnO(BO.sub.3).sub.3in which:M is Ca, or Ca partially substituted with Sr or Ba;Ln is one of the lanthanides of the group comprising Y, Gd, La and Lu.

Abstract: Neodymium-doped gehlenite crystal and laser using said crystal. The crystal according to the invention has the formula Ca.sub.2-x Nd.sub.x Al.sub.2+x Si.sub.1-x O.sub.7 with 0<.times..ltoreq.1. This crystal can be used as a laser emitter (4) optically pumped by a laser diode (6), whose temperature is not controlled by a Peltier element component.

Abstract: Mixed strontium and lanthanide oxides and a laser using monocrystals of these oxides.These oxides with a magnetolead type crystalline structure have the following formula:Sr.sub.x Ln1.sub.y1 Ln2.sub.y2 Ln3.sub.y3 M.sub.z A.sub.a B.sub.b O.sub.19--kin which Ln1 represents at least one trivalent element selected from lanthane, gadolinium and yttrium; Ln2 represents at least one trivalent element selected from neodymium, praseodymium, erbium, holmium and thulium; Ln3 represents an element selected from bivalent europium or trivalent cerium with retention of electric neutrality by virtue of oxygen holes; M represents at least one bivalent metal selected from magnesium, manganese and zinc; A represents at least one trivalent metal selected from aluminum and gallium; B represents a trivalent transition metal selected from chromium and titanium; x, yl, y2, y3, z, a, b and k represent numbers so that 0<x<1, 0.ltoreq.y1<1, 0<y2<1, 0.ltoreq.y3<1, 0<z<1, 10.5<a<12, 0.ltoreq.b.ltoreq.0.

Abstract: Mixed lanthanide-magnesium aluminates and lasers using monocrystals of these aluminates. These lasers in particular incorporate two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbito-aluminate emitting visible or infrared light, amplified between a mirror, a polarizing prism being used for passing to the outside of the laser the amplified light beam. The aluminate is of formula: (La.sub.1-x Tr.sub.x).sub.1-y-v Mg.sub.1-z-t Al.sub.11-u+y+2Z/3 Cr.sub.u O.sub.19-t-3v/3 in which Tr represents (a) at least one single trivalent substance chosen from among lanthanides, Y.sup.3+, Sc.sup.3+, or (b) at least one pair of lanthanides formed from a divalent element and a trivalent element, while retaining the electrical neutrality by adding aluminum or oxygen deficiencies, or any combination of (a) and (b); x is a number such that 0.ltoreq.x<1; y and v are numbers such that 0.ltoreq.y+v.ltoreq.0.4; z and t are numbers such that 0.ltoreq.z+t<1, provided that when z=t=O, y+v is .noteq.

Abstract: Mixed lanthanide-magnesium gallates and laser using monocrystals of these gallates. This laser has two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbite-type gallate emitting a light ranging from the UV to the IR, which is amplified between two mirrors and a polarizing prism serving to pass to the outside of the laser the amplified light beam. The gallate is of formula: ##STR1## in which M.sup.1 represents Nd, Pr, Ce, Nd-Ce or Pr-Ce in the trivalent state; M.sup.2 represents aluminium, optionally partly substituted by scandium and/or indium; k is a number between 0.94 and 1; x is a number between 0 and 1; t is a number such that 0.ltoreq.t.ltoreq.0.05, provided that t is.noteq.0 when x=0 and that x is .noteq.0 when t=0; v is a number such that 0.ltoreq.v+t<1 and z is a number between 0 and 0.5.

Abstract: Mixed lathanum-magnesium aluminates, their production process and lasers using these aluminates.These lasers comprise two flash lamps for longitudinally pumping a bar of an aluminate of formula La.sub.1-x Nd.sub.x Mg.sub.Y Al.sub.11 O.sub.18+y, x and y being numbers such that O<x.ltoreq.0.2 and O<y<1, preferably with y ranging from 0.5 to 0.55, emitting in the infrared, mirrors for amplifying the light emitted by the bar and a polarizing prism for passing the amplified light beam outside the laser.

Abstract: Mixed lanthanide-magnesium aluminates and lasers using monocrystals of these aluminates.These lasers in particular incorporate two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbite-aluminate emitting visible or infrared light, amplified between a mirror, a polarizing prism being used for passing to the outside of the laser the amplified light beam. The aluminate is of formula:(La.sub.1-x Tr.sub.x).sub.1-y-v Mg.sub.1-z-t Al.sub.11-u+y+2z/3 Cr.sub.u O.sub.19-t-3v/3.in which Tr represents a) at least one single trivalent substance chosen from among lanthanides, Y.sup.3+, Sc.sup.3+, or b) at least one pair of lanthanides formed from a divalent element and a trivalent element, while retaining the electrical neutrality by adding aluminium or oxygen deficiencies, or any combination of (a) and (b); x is a number such that 0.ltoreq.x<1; y and v are numbers such that 0.ltoreq.y+v.ltoreq.0.4; z and t are numbers such that 0.ltoreq.z+t<1, provided that when z=t=0, y+v is .noteq.

Abstract: These lasers in particular have two flashlamps (30, 32) for longitudinally pumping a monocrystalline aluminate bar (28) emitting in the visible and near infrared, two mirrors (38, 40) for amplifying the light emitted by the bath, a polarizer prism (42) used for feeding the amplified light beam to the outside of the laser cavity. The magnetoplumbite-type aluminate has in particular the formula:La.sub.1-x Mg.sub.1-y-z Mt.sub.v Al.sub.11+x+2y/ 3-v O.sub.19-z(II)in which Mt represents a transition metal chosen from titanium and zirconium; x is a number such that 0<x<0.3; y and z are numbers such that 0.ltoreq.y+z.ltoreq.1 with 0.ltoreq.y.ltoreq.1 and 0.ltoreq.z.ltoreq.1; v is a number such that 0<v<1.

Abstract: A mixed aluminum oxide having the following formula:X.sup.1.sub.(x.sbsb.1.sub.-x.sbsb.2.sub.) X.sup.2.sub.(x.sbsb.2.sub.) M.sup.1.sub.(y.sbsb.1.sub.-y.sbsb.2.sub.) M.sup.2.sub.(y.sbsb.2.sub.) Al.sub.(z.sbsb.1.sub.-z.sbsb.2.sub.) M.sup.3.sub.(z.sbsb.2.sub.) O.sub.19wherein X.sup.1 and X.sup.2, which can be the same or different, represent a metal selected from the group consisting of lanthanum, praseodymium, neodymium, samarium and gadolinium, provided that X.sup.1 and X.sup.2 are different when X.sup.1 or X.sup.2 represents lanthanum or gadolinium; M.sup.1 and M.sup.2, which can be the same or different, each represent a metal selected from the group consisting of magnesium and divalent transition metals; M.sup.3 represents a trivalent transition metal; x.sub.1 represents a number from 0.8 to 1; y.sub.1 represents a number from 0.7 to 1; z.sub.1 represents a number from 10 to 12; x.sub.2 represents a number from 0 to x.sub.1 ; y.sub.2 represents a number from 0 to y.sub.1 ; and z.sub.