Semiconductor laser device and semiconductor laser device array
In an active layer 15 of a semiconductor laser device 3 , a refractive index type main waveguide 4 is formed by a ridge portion 9 a of a p-type clad layer 17 . Side surfaces 4 g and 4 h of the main waveguide 4 form a relative angle θ, based on a total reflection critical angle θc at the side surfaces 4 g and 4 h , with respect to a light emitting surface 1 a and a light reflecting surface 1 b . The main waveguide 4 is separated by predetermined distances from the light emitting surface 1 a and the light reflecting surface 1 b , and optical path portions 8 a and 8 b , for making a laser light L 1 pass through, are disposed between one end of the main waveguide 4 and the light emitting surface 1 a and between the other end of the main waveguide 4 and the light reflecting surface 1 b . The optical path portions 8 a and 8 b are gain type waveguides and emit light components L 2 and L 3 , which, among the light passing through the optical path portions 8 a and 8 b , deviate from a direction of a predetermined axis A, to the exterior. A semiconductor laser device and a semiconductor laser device array that can emit laser light of comparatively high intensity and can reduce side peaks are thereby realized.
1. A semiconductor laser device comprising:
a first conductive type clad layer;
a second conductive type clad layer;
an active layer, disposed between the first conductive type clad layer and the second conductive type clad layer;
a light emitting surface and a light reflecting surface, disposed so as to oppose each other in a predetermined axial direction;
a refractive index type main waveguide, formed in the active layer, having a pair of side surfaces, and making laser light resonate between the light emitting surface and the light reflecting surface; and
an optical path portion, disposed at least at one of either between the light emitting surface and one end of the main waveguide or between the light reflecting surface and the other end of the main waveguide, wherein
a relative angle θ of the pair of side surfaces of the main waveguide with respect to the light emitting surface and the light reflecting surface is based on a total reflection critical angle θc at the pair of side surfaces, and
the optical path portion is arranged in a manner such that light deviating from the predetermined axial direction in the optical path portion is suppressed in resonance and is emitted from a non-resonance end face region for the resonance suppressed light, differing from a resonance end face region for the laser light which resonates, at least at one surface among the light emitting surface and the light reflecting surface.
2. The semiconductor laser device according to claim 1 , wherein the optical path portion is disposed between the light emitting surface and one end of the main waveguide.
3. The semiconductor laser device according to claim 1 , wherein at least a portion of the optical path portion is a gain type waveguide formed in the active layer.
4. The semiconductor laser device according to claim 1 , wherein the optical path portion has a pair of side surfaces, disposed between the light emitting surface and one end of the main waveguide and forming a refractive index type waveguide, and
for the side surface of the main waveguide at the side, at which an extension line to the light emitting surface and the light emitting surface form an acute angle at an inner side of an extension of the main waveguide, the optical path portion side surface, positioned at the same side as the main waveguide side surface, forms a relative angle with respect to a normal to the light emitting surface that is greater than an angle 2 (90°−θ) and enlarges the optical path portion toward the light emitting surface.
5. The semiconductor laser device according to claim 1 , wherein the optical path portion has a pair of side surfaces, disposed between the light reflecting surface and the other end of the main waveguide and forming a refractive index type waveguide, and
for the side surface of the main waveguide at the side, at which an extension line to the light reflecting surface and the light reflecting surface form an acute angle at an inner side of an extension of the main waveguide, the optical path portion side surface, positioned at the same side as the main waveguide side surface, forms a relative angle with respect to a normal to the light reflecting surface that is greater than an angle 2 (90°−θ) and enlarges the optical path portion toward the light reflecting surface.
6. The semiconductor laser device according to claim 1 , wherein the length of the main waveguide and the mutual interval between the pair of side surfaces of the main waveguide are set so that light that resonates between the light emitting surface and the light reflecting surface in the main waveguide is reflected the same number of times at each of the pair of side surfaces of the main waveguide.
7. The semiconductor laser device according to claim 1 , wherein the relative angle θ of the side surfaces of the main waveguide with respect to the light emitting surface and the light reflecting surface is in a range of θc<θ<θc+1°.
8. The semiconductor laser device according to claim 1 , wherein the relative angle θ of the side surfaces of the main waveguide with respect to the light emitting surface and the light reflecting surface is substantially matched to the total reflection critical angle θc at the side surfaces of the main waveguide.
9. A semiconductor laser device array comprising: a plurality of the semiconductor laser devices according to claim 1 , wherein
the plurality of semiconductor laser devices are formed integrally upon being positioned in a direction that intersects the predetermined axial direction.