Patent ID: 9257810
Filing Date: 2016-02-09
CPC Classification: G02B,H01S

Claim Text:
1. An optical device comprising: a first optical fiber in which an outer shell part is removed in a first area inclusive of an end surface thereof; a second optical fiber in which (i) an outer shell part is removed in a second area inclusive of an end surface thereof and (ii) the end surface of the second optical fiber is fused to the end surface of the first optical fiber; a first medium which (a) has a refractive index lower than (I) a refractive index of an outermost shell part in the first area of the first optical fiber and (II) a refractive index of an outermost shell part in the second area of the second optical fiber and (b) surrounds a side surface in the entire first area of the first optical fiber; and a second medium which (A) has a refractive index higher than a refractive index of the outermost shell part in the second area of the second optical fiber and (B) surrounds a side surface in at least a part of the second area of the second optical fiber, the outermost shell part in the first area of the first optical fiber abutting, in the end surfaces of the respective first and second optical fibers, the outermost shell part in the second area of the second optical fiber, the second optical fiber having, at a boundary between the first medium and the second medium, a diameter larger than a diameter in the first area of the first optical fiber; and the boundary between the first medium and the second medium being closer to the second optical fiber than a point where the first optical fiber and the second optical fiber are fused to each other, the first medium covering said point and a part of the second optical fiber which part is close to said point.