| 摘要 |
An optical semiconductor device includes a semiconductor laser having an equivalent refractive index nc; and a low-reflective coating film disposed on one end face of the semiconductor laser. The low-reflective coating film includes a first-layer coating film having a refractive index n 1 and a thickness d 1 ; and a second-layer coating film having a refractive index n 2 and a thickness d 2 . n 0 and lambda 0 denote refractive index of free space on a surface of the second-layer coating film and the wavelength of laser light produced by the semiconductor laser. Both a real part and an imaginary part of amplitude reflectance, determined by the wavelength lambda 0 , the refractive indexes n 1 and n 2 , and the thicknesses d 1 and d 2 , are zero and only one of refractive indexes n 1 and n 2 is smaller than the square root of a product of the refractive indexes nc and n 0. |
