| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor laser device in which output detection of a laser element is accurately performed with a light receiving element and light is stably outputted, even when output wavelength of the laser element varies due to a temperature rise of the laser element. SOLUTION: A multi-layer film in which films of high refractive index and low refractive index are alternately formed is provided to a light emitting surface of a semiconductor laser element 21 on the light receiving element 22 side. A single layer film of low refractive index is provided to the other light emitting surface. The thickness of the single layer film isλ/4n<SB>1</SB>-λ/2n<SB>1</SB>(whereλ/4n<SB>1</SB>andλ/2n<SB>1</SB>are not included, and n<SB>1</SB>: refractive index of the single layer film). When the outermost layer in the multi-layer film is the layer of high refractive index, its thickness is 0-λ/4n<SB>2</SB>(where 0 andλ/4n<SB>2</SB>are not included, and n<SB>2</SB>: refractive index of the outermost layer). When the outermost layer in the multi-layer film is the layer of low refractive index, its thickness isλ/4n<SB>3</SB>-λ/2n<SB>3</SB>(whereλ/4n<SB>3</SB>andλ/2n<SB>3</SB>are not included, and n<SB>3</SB>: refractive index of the outermost layer). COPYRIGHT: (C)2004,JPO
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