Optical semiconductor device, method of producing the optical semiconductor device, and laser device using optical semiconductor devices

An optical semiconductor device comprising:

• a first waveguide;
• and
• a second waveguide intersecting said first waveguide,
• an intersecting portion of said first and second waveguides comprising:
• first and second cladding layers,
• a light guide layer sandwiched between said first and second cladding layers, and
• a layer structure provided in said light guide layer, said layer structure having a first periodic variation in a refractive index in a predetermined direction with a predetermined angle with respect to a direction in which light is propagated through said first waveguide, and a second periodic variation in an optical gain in the predetermined direction, the first periodic variation having a period identical to that of the second periodic variation, and the first periodic variation and the second periodic variation having a phase difference.

A semiconductor laser device comprising:

• an optical fiber;
• two optical semiconductor devices connected to respective ends of the optical fiber;
• and
• each of said two optical semiconductor devices comprising:
• first and second cladding layers,
• a light guide layer sandwiched between said first and second cladding layers, and
• a layer structure provided in said light guide layer, said layer structure having a first periodic variation in a refractive index in a predetermined direction, and a second periodic variation in an optical gain in the predetermined direction, the first periodic variation having a period identical to that of the second periodic variation, and the first periodic variation and the second periodic variation having a phase difference.

A semiconductor laser device comprising:

• two optical semiconductor devices;
• optical fibers connected to said two optical semiconductor devices so that a ring laser device is formed;
• and
• each of said two optical semiconductor devices comprising:
• first and second cladding layers,
• a light guide layer sandwiched between said first and second cladding layers, and
• a layer structure provided in said light guide layer, said layer structure having a first periodic variation in a refractive index in a predetermined direction, and a second periodic variation in an optical gain in the predetermined direction, the first periodic variation having a period identical to that of the second periodic variation, and the first periodic variation and the second periodic variation having a phase difference.

A semiconductor laser device comprising:

• an array of semiconductor lasers formed on a substrate;
• light branching and amplifying devices coupling said semiconductor lasers so that said array thereof is formed;
• and
• each of said light branching and amplifying devices comprising:
• first and second cladding layers,
• a light guide layer sandwiched between said first and second cladding layers, and
• a layer structure provided in said light guide layer, said layer structure having a first periodic variation in a refractive index in a predetermined direction with a predetermined angle with respect to a direction in which light from an adjacent one of the light branching and amplifying devices is propagated, and a second periodic variation in an optical gain in the predetermined direction, the first periodic variation having a period identical to that of the second periodic variation, and the first periodic variation and the second periodic variation having a phase difference.

A method of producing an optical semiconductor device having a base, said method comprising the steps of:

• (a) forming a first layer structure having a surface on the base, said first layer functioning as one of a light guide layer, a cladding layer and an active layer;
• (b) forming a plurality of grooves on the surface of the first layer structure;
• (c) obliquely projecting a gas onto the surface of the first layer so that a second layer having a refractive index larger than that of the first layer structure is formed on the grooves;
• and
• (d) forming a third layer on the second layer, said third layer having a refractive index smaller than that of said second layer, said third layer functioning as one of an active layer and a light guide layer, wherein the function of said third layer is different from the function of the first layer structure.