Semiconductor chip and optical module

1 . A semiconductor chip comprising:

a waveguide having a terminated face at an output end portion from which light is emitted, the terminated face being located at an internal position inside of the semiconductor chip spaced apart from an emission end face;

a window region made of a bulk semiconductor and disposed between the terminated face of the waveguide and the emission end face;

an open groove formed in the output end portion, the emission end face being a side wall of the open groove formed by etching; and

a cleavage plane provided in the open groove and onto which the light emitted from the emission end face is incident,

wherein

the terminated face of the waveguide is an end face that emits the light to the window region in a direction along a perpendicular line of the terminated face,

a terminated face of the window region forming the emission end face has a perpendicular line in a direction different from a perpendicular line of the cleavage plane, the light that has propagated through the window region is incident onto the terminated face of the window region at an incident angle shifted from the perpendicular line of the terminated face of the window region, and the light incident at the incident angle is refracted and emitted in the direction along the perpendicular line of the cleavage plane.

2 . The semiconductor chip according to claim 1 , wherein a length L of the window region extending from a terminal end of the waveguide to the emission end face is 5 μm<L<15 μm.

3 . The semiconductor chip according to claim 1 , wherein the waveguide is a bent waveguide forming an angle of θ wg with respect to the perpendicular line of the cleavage plane, and when an angle formed between the emission end face and the cleavage plane is defined as θ f , an incident angle of light with respect to the emission end face is defined as θ 1 and the light is refracted at the emission end face and emitted to the open groove at an emission angle θ 2 , θ wg =θ 2 −θ 1 and θ f =θ 2 is satisfied.

4 . The semiconductor chip according to claim 3 , wherein the incident angle θ 1 of light with respect to the emission end face is 4°<θ 1 <8°.

5 . The semiconductor chip according to claim 1 , further comprising:

a DFB laser having an active layer composed of a multiple quantum well that generates an optical gain by current injection, and a diffraction grating;

an EA modulator having an absorption layer composed of a multiple quantum well having a composition different from that of the DFB laser; and

a semiconductor optical amplifier having an active region with the same composition as the DFB laser and connected to the waveguide of the output end portion,

wherein the DFB laser, the EA modulator, and the semiconductor optical amplifier are monolithically integrated on a same substrate.

6 . The semiconductor chip according to claim 5 , wherein the DFB laser, the EA modulator, and the semiconductor optical amplifier are formed on a (100) plane of an InP substrate, and an optical axis of the DFB laser is a direction of a crystallographic orientation [011] or [01-1-] of the substrate.

7 . An optical module, comprising:

a semiconductor chip mounted in a package and including:

a waveguide having a terminated face at an output end portion from which light is emitted, the terminated face being located at an internal position inside of the semiconductor chip spaced apart from an emission end face;

a window region made of a bulk semiconductor and disposed between the terminated face of the waveguide and the emission end face;

an open groove formed in the output end portion, the emission end face being a side wall of the open groove formed by etching; and

a cleavage plane provided in the open groove and onto which the light emitted from the emission end face is incident,

wherein

the terminated face of the waveguide is an end face that emits the light to the window region in a direction along a perpendicular line of the terminated face,

a terminated face of the window region forming the emission end face has a perpendicular line in a direction different from a perpendicular line of the cleavage plane, the light that has propagated through the window region is incident onto the terminated face of the window region at an incident angle shifted from the perpendicular line of the terminated face of the window region, and the light incident at the incident angle is refracted and emitted in the direction along the perpendicular line of the cleavage plane, and

wherein the waveguide is a bent waveguide forming an angle of θ wg with respect to the perpendicular line of the cleavage plane, and when an angle formed between the emission end face and the cleavage plane is defined as θ f , an incident angle of light with respect to the emission end face is defined as θ 1 and the light is refracted at the emission end face and emitted to the open groove at an emission angle θ 2 , θ wg =θ 2 −θ 1 and θ f =θ 2 is satisfied.

8 . The optical module according to claim 7 , wherein the incident angle θ 1 of light with respect to the emission end face is 4°<θ 1 <8°.