Hitachi, Ltd.

Yasutoshi Kashiwada

Naoki Chinone

Takashi Kajimura

Takao Kuroda

Kunio Aiki

Yoshihisa Fujisaki

Shinji Tsuji

Tsukuru Ohtoshi

Motohisa Hirao

Hitoshi Nakamura

Kazuhisa Uomi

Tadashi Fukuzawa

Yuichi Ono

Toshihiro Kawano

Kenji Hiruma

Shinichi Nakatsuka

Jun-ichi Umeda

Shigeo Yamashita

Atsushi Suzuki

Hirobumi Ouchi

Shinkichi Tanimizu

Hiroyoshi Matumura

Yoshio Furuhata

Akio Oishi

A semiconductor laser having a stripe-like lasing region, wherein the structure of the lasing region such as the mechanism of optical guiding of the lateral mode control structure is made different between the central portion in the lasing region and portions close to facets, in order to reduce optical feedback induced noise and astigmatism, and to facilitate the manufacture thereof.

Semiconductor laser

A distributed feedback semiconductor laser provided with a grating which effects optical feedback by means of periodic corrugation disposed inside an optical resonator. The optical resonator has at least two regions having different Bragg wavelengths, and these regions are arranged longitudinally in the direction of an optical axis. The laser device can realize stable single longitudinal mode oscillation through variation of the refractive indexes of the regions nonuniformly around an average value.

Distributed-feedback semiconductor laser device

Disclosed is a distributed feedback semiconductor laser provided with a grating which effects optical feedback by means of periodic corrugation disposed inside an optical resonator. The optical resonator has at least two regions having different bragg wavelength, and these regions are arranged longitudinally in the direction of an optical axis. The laser device can realize stable single longitudinal mode oscillation.

Disclosed herein is a semiconductor laser device including at least an optical confinement region having at least first, second and third semiconductor layers disposed on a semiconductor substrate, wherein the first and third semiconductor layers have refractive indices greater than the refractive index of the second semiconductor layer but have forebidden band gap smaller than that of the second semiconductor layer and the conductivity types of the first and third semiconductor layers are opposite to each other; the second semiconductor layer has a smooth change of its thickness in two directions parallel to a junction surface of the optical confinement region; and a difference exists in the refractive indices of the first and third semiconductor layers.

Buried heterojunction laser

Disclosed is a semiconductor laser device having at least an optical confinement region which includes a first semiconductor layer, and second and third semiconductor layers holding the first semiconductor layer therebetween and having a greater band gap and a lower refractive index than those of the first semiconductor layer, the second and third semiconductor layers having conductivity types opposite to each other; characterized in that the relationship between a donor density (N.sub.D .times.10.sup.17 cm.sup.-3) of the n-conductivity type semiconductor layer in the second and third semiconductor layers and a proportion (.GAMMA..sub.n %) of an optical output existing in the n-conductivity type semiconductor layer relative to a total optical output of the laser is set at N.sub.D .times..GAMMA..sub.n .gtoreq.500. Noise characteristics are sharply improved.

Semiconductor laser device

A semiconductor laser device including at least a laminated region of first, second, third and fourth semiconductor layers on a predetermined semiconductor substrate, wherein the third semiconductor layer has a refractive index smaller than that of the second semiconductor layer; the first and fourth semiconductor layers have a refractive index smaller than that of the second and third semiconductor layers and have a conductivity type opposite that of the second and third semiconductor layers; the forbidden band gap of the first and third semiconductor layers is greater than that of the second semiconductor layer; and at least the second and third semiconductor layers are bent so that the laser light generated inside the second semiconductor layer in the proximity of the laser light-emitting facets generates optical coupling in the third semiconductor layer and is emitted from the crystal facets of the third semiconductor layer. The device of the present invention is effective for increasing the output of semiconductor laser devices.

In a semiconductor laser device having at least a first semiconductor layer, second and third semiconductor layers which are formed in a manner to sandwich the first semiconductor layer and which have a wider band gap and a lower refractive index than those of the first semiconductor layer, an optical resonator and carrier injection means; a semiconductor laser device characterized in that at least said first semiconductor layer has an angle of inclination (.theta.) relative to an axis which is perpendicular to optically flat faces constituting said optical resonator. The inclination angle .theta. (rad) should most preferably lie in a range of: ##EQU1## where .theta..sub.z denotes a reflection angle, .theta..sub.c a critical angle, W 1/2 of a thickness of a waveguide, and l a cavity length. The laser device is effective for preventing laser facets from breaking down, and can produce high power.

Infrared-infrared phosphors having a composition represented by the general formula

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Nishitama, Japan

Yasutoshi Kashiwada