Photocoupler and method for producing the same

摘要

A photocoupler according to the present invention includes: an optical waveguide including a substrate, at least a first dielectric layer provided on the substrate, the first dielectric layer having a tapered structure whose thickness varies in an x-direction in which light is propagated after coupling, and a second dielectric layer provided on the first dielectric layer; a light incidence component provided above the optical waveguide, which causes light incident thereon to be directed toward a surface of the optical waveguide at a prescribed angle; and a bonding section for bonding the light incidence component to the optical waveguide. The bonding section has an edge surface which makes contact with the surface of the waveguide in a straight line and has a portion which makes contact with neither the light incidence component nor the surface of the optical waveguide. The tapered structure of the first dielectric layer has a shape set such that a radiation pattern of light with a wavelength &lgr; output from the optical waveguide of the photocoupler fulfills the following expression:PPa.sub.n- 1 (1-r.sub.n) a.sub.n (1-r.sub.n+1)PP where &agr;. sub.rn is a radiation coefficient at a section X.sub.n-1 X X. sub.n of the first dielectric layer where a thickness thereof varies in a tapering manner; a.sub.n is an amplitude at a distance X.sub.n from the edge surface of the bonding section; and r.sub. n is exp(k.sub.0 &agr;. sub.rn &Dgr;X); k.sub.0 is 2&pgr;/&lgr;; and &Dgr;X is X.sub.n -X. sub.n- 1.