A wavelength converting structure is disclosed, the wavelength converting structure including an SWIR phosphor material having emission wavelengths in the range of 1000 to 1700 nm, the SWIR phosphor material including at least one of a perovskite type phosphor doped with Ni.sup.2+, a perovskite type phosphor doped with Ni.sup.2+ and Cr.sup.3+, and a garnet type phosphor doped with Ni.sup.2+ and Cr.sup.3+.

A value document has a security marking in the form of two luminescent substances whose the emission spectra partially overlap in a primary emission range. The emission spectra have a degree of overlap of less than 80% and more than 5%, wherein the luminescent substances have different individual decay times in the primary emission range. The individual decay times of the luminescent substances differ from each other by more than 50% with reference to the shortest individual decay time.

Embodiments of the invention include an infrared-emitting phosphor comprising (La,Gd).sub.3Ga.sub.5xyAl.sub.xSiO.sub.14:Cr.sub.y, where 0x1 and 0.02y0.08. In some embodiments, the infrared-emitting phosphor is a calcium gallogermanate material. In some embodiments, the infrared-emitting phosphor is used with a second infrared-emitting phosphor. The second infrared-emitting phosphor is one or more chromium doped garnets of composition Gd.sub.3x1Sc.sub.2x2yLu.sub.x1+x2Ga.sub.3O.sub.12:Cr.sub.y, where 0.02x10.25, 0.05x20.3 and 0.04y0.12.

Provided is a light source device including: at least one light emitting element of at least one type; at least one far-red phosphor that, when excited by output light from the light emitting element, emits light having a peak in a wavelength range of 680 nm or more to less than 780 nm; and at least one phosphor that, when excited by the output light from the light emitting element, emits light having a peak in a wavelength range different from the wavelength range of the light emitted from the far-red phosphor. The spectrum of light emitted from the light source device has characteristic A below. This light source device has sufficient emission intensity over the entire visible range, i.e., over a wavelength range of from 400 nm to 750 nm inclusive. Characteristic A: The ratio of a minimum emission intensity to a maximum emission intensity in a wavelength range of from 400 nm to 750 nm inclusive is 20% or more.

Embodiments of the invention include an infrared-emitting phosphor comprising (La,Gd).sub.3Ga.sub.5xyAl.sub.xSiO.sub.14:Cr.sub.y, where 0x1 and 0.02y0.08. In some embodiments, the infrared-emitting phosphor is a calcium gallogermanate material. In some embodiments, the infrared-emitting phosphor is used with a second infrared-emitting phosphor. The second infrared-emitting phosphor is one or more chromium doped garnets of composition Gd.sub.3x1Sc.sub.2x2yLu.sub.x1+x2Ga.sub.3O.sub.12:Cr.sub.y, where 0.02x10.25, 0.05x20.3 and 0.04y0.12.

The present invention relates to a phosphor and a composition.

Embodiments of the invention include an infrared-emitting phosphor comprising (La,Gd).sub.3Ga.sub.5xyAl.sub.xSiO.sub.14:Cr.sub.y, where 0x1 and 0.02y0.08. In some embodiments, the infrared-emitting phosphor is a calcium gallogermanate material. In some embodiments, the infrared-emitting phosphor is used with a second infrared-emitting phosphor. The second infrared-emitting phosphor is one or more chromium doped garnets of composition Gd.sub.3x1Sc.sub.2x2yLu.sub.x1+x2Ga.sub.3O.sub.12:Cr.sub.y, where 0.02x10.25, 0.03x20.3 and 0.04y0.12.

An object of the present invention is to provide an infrared light-emitting phosphor which emits light in a wavelength range where the sensitivity of a detector is high by combination with a semiconductor light-emitting element that emits light in the visible light region, and to provide an infrared light-emitting device using the infrared light-emitting phosphor. The object can be achieved with a light-emitting device including a semiconductor light-emitting element that emits ultraviolet light or visible light and a phosphor that absorbs ultraviolet light or visible light emitted from the semiconductor light-emitting element and emits light in the infrared region, wherein an emission peak wavelength in the infrared region of the phosphor emitting in the infrared region is from 750 to 1,050 nm, and the half width of an emission peak waveform is more than 50 nm.

Disclosed are a red light and near-infrared light-emitting material and a preparation method thereof, and a light-emitting device including the light-emitting material. The red light and near-infrared light-emitting material contains a compound represented by a molecular formula, aSc.sub.2O.sub.3.Math.Ga.sub.2O.sub.3.Math.bR.sub.2O.sub.3, wherein the element R includes one or two of Cr, Ni, Fe, Yb, Nd or Er; 0.001?a?0.6; and 0.001?b?0.1. The light-emitting material can be excited by a spectrum having a wide wavelength range (ultraviolet light or purple light or blue light) to emit light with a wide spectrum of 650 nm to 1700 nm or multiple spectra, thus having higher light-emitting intensity.

An optical device includes an LED chip, a visible-light luminescent material, and a near-infrared luminescent material, wherein a luminous power of light emitted by the near-infrared and visible-light luminescent materials in a band of 650-1000 nm under the excitation of the LED chip is A, and a sum of a luminous power of light emitted by the near-infrared and visible-light luminescent materials in a band of 350-650 nm under the excitation of the LED chip and a luminous power of residual light emitted by the LED chip in the band of 350-650 nm after the LED chip excites the near-infrared and visible-light luminescent materials is B, with B/A*100% being 0.1%-10%. According to the implementation where the optical device employs the LED chip to combine the near-infrared luminescent material and the visible-light luminescent material simultaneously.