| 摘要 |
PROBLEM TO BE SOLVED: To provide a ridge type optical waveguide in which wide band light beams having wavelengths of 1.2 to 1.70μm are effectively confined. SOLUTION: All parts of the waveguide are made of semiconductor materials. The waveguide is made of a layer construction, i.e., a lower section clad layer 2, a lower section SCH layer 7a, a core layer 3, an upper section SCH layer 7b and an upper section clad layer 4 and they are laminated in this order on a substrate 1. Moreover, the upper section of the waveguide has a ridge section A1 in which a ridge a1 having a prescribed plane pattern with a width W is formed as an optical waveguide. Furthermore, when a standardized frequency V(λ) against the light beam having an wavelengthλis expressed by V(λ)=(2π/λ).W. na 2<2> (λ)-nb <2> (λ)}<1/2> where na (λ) is an equivalent refractive index of the layer construction that constitutes the section A1 against a light beam having a wavelengthλand n6 (λ) is an equivalent refractive index of the layer construction which constitutes a portion A2 that is other than the section A1 against the light beam having a wavelengthλ, the following relationship is established, i.e., 0.95<=V(λ1 )/-V(λ2 )<=1.05 whereλ1 andλ2 are placed within 1.2μm to 1.70μm andλ2 is 1.3μm, against the light beams having wavelengthsλ1 andλ2 . |
