Matsushita Electric Industrial Co., Ltd.

Kazuo Fujimoto

Kunio Itoh

Hirokazu Shimizu

Takashi Sugino

Masaru Wada

Iwao Teramoto

Hirotsugu Hattori

Hiroyuki Mizuno

Yoshimi Tanaka

Eiiti Kosoegawa

Yuichiro Takayama

In a laser of such type that the distribution of the effective refractive index varies in a direction which is along the face of its active layer and perpendicular to the direction of the laser light transmission, thereby defining the active region to be between a pair of refractive index changing zones, the refractive indexes of a pair of end surfaces of a laser resonator (i.e. the active region) is made smaller than the intrinsic refractive indexes of the cleavage face of the active layer.

Semiconductor laser

In a semiconductor laser of terraced substrate type, comprising on a terraced substrate (11) of n-GaAs substrate, a first clad layer (12) of n-GaAlAs, an active layer (13) of non-doped GaAlAs, a second clad layer (14) of p-GaAlAs and a current limiting layer (15) of n-GaAs, and further thereon a thick overriding layer (19) of n-GaAlAs with strip shaped opening (191), are epitaxially formed, and a current injection layer (16) is formed by Zn diffusion through the opening (191) in a manner one corner (161) of the injection front penetrate the current limiting layer (15) and reaches the second clad layer (14). By means of thick overriding layer (19), shortcircuiting between the active layer (13) and a p-side electrode (7) is prevented.

Terraced substrate semiconductor laser

A cathodic protection, anticorrosive circuit comprises a diode connection of a transistor or a Schotkky diode interconnected between a buried structure to be protected and a galvanic anode or the like so that even when the difference in potential between them is relatively low, an effective forward or anticorrosion current may flow while positively preventing the reverse current which causes the corrosion of the buried structure.

Anticorrosive circuit for a buried structure

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Takatsuki, Japan

Kazuo Fujimoto