Abstract: A semiconductor laser diode optically coupled to an optical fiber is mounted on a stem. A cap having a light transmissive hole between the optical fiber and the semiconductor laser diode is fixed to the stem. A ball lens is fixed in the light transmissive hole. The ball lens has a refractive index of 1.9 or more and a diameter between 1.5 mm and 2.5 mm.

Abstract: A semiconductor optical device which has a ridge structure includes a waveguide area between paired mesa trenches; first and second mount areas disposed outside the mesa trenches; a first spacer layer disposed in a first mount area and a second spacer layer disposed in a second mount area; a first metal layer electrically connected to an upper cladding layer in the waveguide area and extending from the waveguide area over the first mount area; and a second metal layer disposed over the second mount area. Thicknesses from a back surface of the semiconductor optical device to the first metal layer in the first mount area and to the second metal layer in the second mount area are both larger than thickness from the back surface to the first metal layer in the waveguide area.

Abstract: A semiconductor laser array device for outputting a higher power includes: a plurality of semiconductor laser chips, arranged in a predetermined pitch; a submount for mounting each semiconductor laser chip; and a heat sink for dissipating heat from the semiconductor laser chip through the submount; wherein a distance S between the centers of the chips and a thickness T of the submount satisfy the following inequality: 2×T?S?10×T, whereby improving efficiency of heat dissipation with a good process yield.

Abstract: A semiconductor laser diode optically coupled to an optical fiber, is mounted on a stem. A cap having a light transmissive hole between the optical fiber and the semiconductor laser diode is fixed to the stem. A ball lens is fixed in the light transmissive hole. The ball lens has a refractive index of 1.9 or more and a diameter between 1.5 mm and 2.5 mm.

Abstract: A semiconductor optical device which has a ridge structure comprises: a waveguide area which is between paired mesa trenches; first and second mount areas disposed outside the mesa trenches; a first spacer layer disposed in the first mount area and a second spacer layer disposed in the second mount area; a first metal layer which is electrically connected to the upper cladding layer in the waveguide area and which expands from the waveguide area over the first mount area; and a second metal layer which is disposed over the second mount area. The height from the back surface to the first metal layer in the first mount area and the height from the back surface to the second metal layer in the second mount area are both higher than the height from the back surface to the first metal layer in the waveguide area.