A light-emitting device includes: a light source that radiates primary light; and a first phosphor that absorbs the primary light and converts the primary light into first wavelength-converted light having a longer wavelength than the primary light, the first wavelength-converted light includes fluorescence based on electron energy transition of Cr.sup.3+, and a fluorescence spectrum of the first wavelength-converted light has a maximum fluorescence intensity value in region of a wavelength exceeding 710 nm.

An oxide fluorescent material has a composition represented by the following formula (1).

(Ga.sub.1-uM.sup.1.sub.u).sub.2(Ge.sub.1-vM.sup.2.sub.v).sub.wO.sub.x:Cr.sub.y,M.sup.3.sub.z(1), wherein M.sup.1 represents at least one element selected from the group consisting of Al, Sc, and In; M.sup.2 represents at least one element selected from the group consisting of Si, Ti, Zr, Sn, and Hf, M.sup.3 represents at least one element selected from the group consisting of Ni, Eu, Fe, Mn, Nd, Tm, Ho, Er, and Yb; and u, v, w, x, y, and z satisfy 0u1.0, 0v0.5, 1.0w3.0, 5x9, 0.005y1.0, and 0z0.5, respectively.

Green-emitting phosphors are useful in devices including an LED light source radiationally coupled and/or optically coupled to the phosphors, which are selected from [Ba.sub.1abSr.sub.aCa.sub.b].sub.x[Mg,Zn].sub.y(UO.sub.2).sub.z([P,V]O.sub.4).sub.2(x+y+z)/3, where 0a1, 0b1, 0.75x1.25, 0.75y1.25, 0.75z1.25; and [Ba,Sr,Ca,Mg,Zn].sub.p(UO.sub.2).sub.q[P,V].sub.rO.sub.(2p+2q+5r)/2, where 2.5p3.5, 1.75q2.25, 3.5r4.5.

A wavelength converter includes a first phosphor activated with Cr.sup.3+; and a second phosphor activated with at least one ion of Ce.sup.3+ or Eu.sup.2+. A fluorescence spectrum of a fluorescence emitted by the second phosphor has a peak where a fluorescence intensity shows a maximum value in a wavelength range of 500 nm or more to less than 580 nm. The wavelength converter emits a fluorescence having a light component over an entire range of 500 nm or more to less than 580 nm. The wavelength converter emits a light having a spectrum in which a ratio of a minimum light emission intensity to a maximum light emission intensity is 40% or less in a wavelength range of 550 nm or more to 700 nm or less.

Green-emitting phosphors are useful in devices including an LED light source radiationally coupled and/or optically coupled to the phosphors, which are selected from [Ba.sub.1-a-bSr.sub.aCab].sub.x[Mg,Zn].sub.y(UO.sub.2).sub.z[P,V]O.sub.4).sub.2(x+y+z)/3, where 0a1, 0b1, 0.75x1.25, 0.75y1.25, 0.75z1.25; and [Ba,Sr,Ca,Mg,Zn].sub.p(UO.sub.2).sub.q[P,V].sub.rO.sub.(2p+2q+5r)/2, where 2.5p3.5, 1.75q2.25, 3.5r4.5.

A wavelength converting structure is disclosed, the wavelength converting structure including a spinel type SWIR phosphor material having emission wavelengths in the range of 1000 to 1700 nm, the SWIR phosphor material including AE.sub.1-x-zA.sub.z+0.5(x-y)D.sub.2+0.5(x-y)-z-u E.sub.zO.sub.4:Ni.sub.y,Cr.sub.u where AE=Mg, Zn, Co, or Be, or mixtures thereof, A=Li, Na, Cu, or Ag, or mixtures thereof, D=Ga, Al, B, In, or Sc, or mixtures thereof, and E=Si, Ge, Sn, Ti, Zr, or Hf, or mixtures thereof; where 0x1, 0<y0.1, 0z1, 0u0.2.

Provided is a phosphor represented by general formula (1) below,
(Gd.sub.1-x-y,Ln.sub.y,M.sup.II.sub.x).sub.3M.sup.III.sub.2(Ga.sub.1-z,M.sup.IV.sub.z).sub.3O.sub.12:Cr.sup.3+(1) where, in the formula, Ln is one or more elements selected from La, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Yb, and Lu, M.sup.II is a divalent element, M.sup.III is a trivalent element, M.sup.IV is a tetravalent element, and x, y, and z satisfy 0<x<0.5, 0y<0.5, and 0<z<0.5.

The purpose of the present invention is to increase the amount of near-infrared light emitted by a phosphor excited by near-ultraviolet light to blue light. The present invention relates to a phosphor containing gallium oxide Ga.sub.2O.sub.3 as the base composition, one or two elements selected from Cr and Fe as the light-emitting center, and aluminum fluoride AlF.sub.3 as the flux.

An oxide fluorescent material comprises: at least one first element M.sup.1 selected from Li, Na, K, Rb, and Cs; at least one second element M.sup.2 selected from Mg, Ca, Sr, Ba, and Zn; at least one third element M.sup.3 selected from B, Al, Ga, In, and rare earth elements; at least one fourth element M.sup.4 selected from Si, Ti, Ge, Zr, Sn, Hf, and Pb; O; and Cr, wherein when the molar ratio of the at least one fourth element M.sup.4 in 1 mol of the composition is 5, the molar ratio of the at least one first element M.sup.1 is 0.7 or more and 1.3 or less, the molar ratio of the at least one second element M.sup.2 is 1.5 or more and 2.5 or less, the molar ratio of the at least one third element M.sup.3 is 0.7 or more and 1.3 or less, the molar ratio of oxygen is 12.9 or more and 15.1 or less, and the molar ratio of Cr is more than 0 and 0.2 or less, and wherein the oxide fluorescent material has a light emission peak wavelength in a range of 700 nm or more and 1,050 nm or less in a light emission spectrum of the oxide fluorescent material.

A first luminescent material having peak emission wavelengths in the range of 1600-1900 nm comprises a Cr.sup.3+ and Tm.sup.3+ co-doped garnet phosphor having the general formula (Gd.sub.3-u-yTm.sub.yRE.sub.u) [Ga.sub.2-a-b-d-eLu.sub.aCr.sub.bSc.sub.d Al.sub.e]{Ga.sub.3-cAl.sub.c}O.sub.12 with RE=La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0u2, 0<y1.5, 0a1, 0<b0.3, 0c3, 0d0.5, 0e1.8. A second luminescent material having peak emission wavelengths in the range of 1400-1600 nm comprises a Cr.sup.3+ and Ni.sup.2+ co-doped garnet phosphor having the general formula (Gd.sub.3-uRE.sub.u) [Ga.sub.2-a-b-d-eNi.sub.aCr.sub.bL.sub.d Al.sub.e]{Ga.sub.3-cAl.sub.c}O.sub.12 with RE=La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L=Ti, Zr, Hf, Sn, Ge, Si and 0u2, 0<a0.1, 0<b0.3, 0<b3, 0c0.15, 0e2. A light source comprises the first and second luminescent materials and one or more semiconductor light emitting diodes arranged to excite luminescence from the luminescent materials to provide short wavelength infrared emission over the range 1300-2000 nm.