Patent ID: 7546014
Filing Date: 2009-06-09
Classification: G02B

Abstract:
1. An optical directional coupler comprising: two straight optical waveguides having respective cores extending longitudinally close to each other to form an optical coupler portion, each core of each straight optical waveguide having a centerline; and a tapered optical waveguide having a core connected to the core of at least one of the straight optical waveguides; wherein a width of the core of the tapered optical waveguide becomes narrow toward the at least one of the straight optical waveguides and a profile of the tapered waveguide is asymmetric relative to the centerline of the core of the at least one of the straight optical waveguides, wherein a width of the core of the straight optical waveguide and a distance between the cores of the two straight optical waveguides are determined by a V-parameter V and a coupling coefficient K, wherein the V-parameter V is represented by; wherein the coupling coefficient K is represented by wherein K is represented by wherein γ is represented by and wherein λ is a wavelength of light to be transmitted, n1 is a value of refractive index of the cores, W