Patent ID: 8537872

Claim:
A light emitting device comprising: a first cladding layer; an active layer formed above the first cladding layer; and a second cladding layer formed above the active layer, wherein the active layer includes a first side surface and a second side surface, at least a part of the active layer configures a first gain region and a second gain region, the first gain region has a first end surface on the second side surface, a third end surface on the first side surface and a reflecting plane between the first end surface and the third end surface, and the second gain region has a second end surface on the second side surface and a fourth end surface on the first side surface, a part of the first end surface of the first gain region overlaps with the second end surface of the second gain region to configure an overlapping plane, a first center line connecting a first center of the first end surface and a third center of the reflection plane is angled relative to a perpendicular direction relative to the second side surface, a second center line connecting a second center of the second end surface and a fourth center of the fourth end surface is angled relative to the perpendicular direction, and the first center line and the second center line intersect at an intersection point, the intersection point is disposed in an opposite side of the second side surface to the active layer side, in a plan view, the first gain region is disposed from the first end surface to the third end surface with a constant width W, in the plan view, the second gain region is disposed from the second end surface to the fourth end surface with the constant width W, and when a length between the intersection point and the overlapping plane is L, the width W and the length L satisfy the following formula 1; 0 <L<W (1).