Patent ID: 7102174

Claim:
A light emitting device comprising a substrate transparent at the emission wavelength and an active layer structure formed on such substrate, wherein the light emitting device has a first-conduction-type clad layer having the same conduction type as said substrate and a single first-conduction-type, low-refractive-index layer for suppressing spectral-intensity-modulation due to the substrate-mode, wherein said first-conduction-type clad layer is provided between said substrate and said active layer structure, wherein said first-conduction-type, low-refractive-index layer is provided between said substrate and said first-conduction-type clad layer, wherein a relation expressed by the following inequality is satisfied: n sub >n clad1 >n LIL1 (inequality 1) where n sub represents the refractive index at the emission wavelength of said substrate, n clad1 represents the real part of an average refractive index at the emission wavelength of said first-conduction-type clad layer, and n LIL1 represents the refractive index at the emission wavelength of said first-conduction-type, low-refractive-index layer, and wherein the thickness of said first-conduction-type clad layer is 2.0 to 3.5 μm.