Kabushiki Kaisha Toshiba

Akio Makuta

Akira Tanaka

Hideo Shiozawa

Koichi Gen-Ei

Osamu Horiuchi

Yoshiyuki Itoh

A semiconductor laser device comprises: a cladding layer of a first conductivity type; an active layer provided on the cladding layer; and a cladding layer of a second conductivity type provided on the active layer. At least a part of the cladding layer of the second conductivity type has a ridge stripe. The ridge stripe includes: an upper part having substantially vertical sidewalls; and a lower portion having sidewalls inclined so that the stripe becomes wider toward the active layer.

Semiconductor laser device and its manufacturing method

A laser element has a first periodic structure (i.e., a diffraction grating) provided along an optical waveguide, and optical feedback is performed by the first periodic structure. Structural factors, including at least one of the width, thickness and refractive index of the optical waveguide, the composition of the laser medium, or the period of the first periodic structure is continuously changed at least in part in the axial direction of a cavity In such a manner that the continuous change provides a periodic structure of second, third or higher order.

Laser element

A periodic structure is formed along the laser medium in the axial direction of a cavity. One of the end facet of the cavity has high reflectivity and the other end facet has low reflectivity. A phase discontinuous portion of the periodic structure is disposed in position deviated from the central portion of the cavity towards the high-reflectivity end facet. The phase discontinuous portion is formed of a phase shifting portion or a phase shifting area having the same effect as the phase discontinuity. The phase shift .DELTA..PHI. of the phase shifting portion or phase shifting area is set to exceed 3.pi./4 which is represented in terms of the phase of waveguiding light (which corresponds to 3.lambda./8 when the lasing wavelength is .lambda.). Thus, the performances of high power and linearity of light output can be simultaneously achieved.

High power distributed feedback semiconductor laser excellent in

Method of manufacturing phase-shifted diffraction grating

Laser device and method of manufacturing the same

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Yokohama, Japan

Akio Makuta