Patent ID: 8729579

Claim:
An illuminating device comprising at least a first nitride-based semiconductor light-emitting element and a second nitride-based semiconductor light-emitting element, wherein the first nitride-based semiconductor light-emitting element and the second nitride-based semiconductor light-emitting element each comprise a semiconductor chip, wherein the semiconductor chip comprises a nitride-based semiconductor multilayer structure formed from an Al x In y Ga z N (x+y+z=1, x≧0, y≧0, z≧0) semiconductor, and the nitride-based semiconductor multilayer structure comprises an active layer region formed from a nitride semiconductor layer, wherein the Al x In y Ga z N (x+y+z=1, x≧0, y≧0, z≧0) semiconductor is a GaN-based semiconductor, wherein the active layer region is at an angle of 1° or more with an m plane, and an angle formed by a normal line of a principal surface in the active layer region and a normal line of the m plane is 1° or more and 5° or less, wherein the first nitride-based semiconductor light-emitting element and the second nitride-based semiconductor light-emitting element each emit polarized light from the active layer region, and wherein, when the polarized light emitted from the first nitride-based semiconductor light-emitting element and the polarized light emitted from the second nitride-based semiconductor light-emitting element have wavelengths λ 1 and λ 2 , respectively, and thicknesses of the semiconductor chips of the first nitride-based semiconductor light-emitting element and the second nitride-based semiconductor light-emitting element are given as d 1 and d 2 , respectively, the following relations are satisfied: λ1<λ2; d1<d2; 420 nanometers≦λ 1 ≦470 nanometers; and 110 micrometers≦d 1 ≦150 micrometers; wherein an optical polarization ratio of the first nitride-based semiconductor light-emitting element is not less than 0.9, and wherein an optical polarization ratio of the second nitride-based semiconductor light-emitting element is not less than 0.9.