Patent ID: 8170385

Claim:
A light coupler, comprising: a plurality of light input terminals; a plurality of light output terminals; a plurality of half mirrors; and an optical wave guide connecting the plurality of the light input terminals, the plurality of the light output terminals, and the plurality of the half mirrors, and having a kinked line shape, wherein each of the plurality of half mirrors is placed at a respective corner of the kinked line shape, wherein the optical wave guide includes a polygon network, wherein each of the plurality of the half mirrors is placed at a respective corner of the polygon network, wherein for a number of the plurality of the input terminals Ni, a number of the plurality of the output terminals No, and a number of the plurality of the half mirrors N, Ni, No, and N satisfy following relations: Ni≦N and No≦N, wherein the polygon network comprises N corners, wherein the optical wave guide comprises an optical reactive resin; wherein the plurality of the half mirrors comprises a first half mirror, a second half mirror and a third half mirror, wherein a first optical path length between the first and the third half mirror is longer than a second optical path length between the first and the second half mirror, and a third optical path length between the second and the third half mirror, and wherein the second half mirror has a transparency for P-wave lower than 90% and a reflectivity for S-wave lower than 90%.