Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Hiromasu Matsuoka

Yasuyuki Nakagawa

Harumi Nishiguchi

Yasuhiro Kunitsugu

Kazushige Kawasaki

Kimio Shigihara

Junichi Horie

Tetsuya Yagi

Kyosuke Kuramoto

Yosuke Suzuki

Toshihiko Shiga

Masatsugu Kusunoki

Takeo Shirahama

A semiconductor light-emitting device includes a light generation unit generating light with an oscillation wavelength &#x3bb;, a light outgoing facet from which light generated at the light generation unit emerges, a light reflecting facet at which light generated at the light generation unit is reflected, and a high reflection film at the light reflecting facet and made of a dielectric multilayered film of at least three layers. The high reflection film includes a first layer which is in contact with the light reflection facet, is constituted of AlO, and has a thickness smaller than &#x3bb;/4n, wherein n is the refractive index of AlO, a second layer which is in contact with the first layer, and a third layer which is in contact with the second layer and has a refractive index different from the refractive index of the second layer.

Semiconductor laser device including highly reflective coating film

A GaN laser, includes a coating film on a front end surface through which laser light is emitted. The coating film includes a first insulating film in contact with the front end surface and a second insulating film on the first insulating film. The optical film thickness of the second insulating film is an odd multiple of &#x3bb;/4 with respect to the wavelength &#x3bb; of laser light produced by the semiconductor laser. The adhesion of the first insulating film to GaN is stronger than the adhesion of the second insulating film to GaN. The refractive index of the second insulating film is 2 to 2.3 thick. The first insulating film is 10 nm or less. The first insulating film is an oxide film having a stoichiometric composition.

Semiconductor laser

A semiconductor laser device includes a semiconductor laser body including a resonator and having a front end face and a rear end face facing each other, the resonator being located between the front end face and the rear end face. The front end face emits principal laser light. A reflectance control film is disposed on the front end face or the rear end face of the semiconductor laser body and is made up of either an aluminum oxide film or a five-layer film including the aluminum oxide film disposed such that it is the layer in the five-layer film farthest from the front end face or the rear end face. A silicon oxide film is disposed on the aluminum oxide film of the reflectance control film and has a thickness of 20 nm or less.

Semiconductor laser device

A semiconductor laser device comprises a GaN substrate having a refractive index of 3.5 or below, a semiconductor layer laminated on the substrate, and a pair of facets forming a resonator and in face-to-face-relation to each other in a direction perpendicular to the direction of the laminated layer. One of the facets of the resonator includes a low reflection film, of a first dielectric film, a second dielectric film, a third dielectric film, and a fourth dielectric film. When the refractive indexes of these films are taken as n, n, n, and n, nand n=n. The following relationship between the first dielectric film and the third dielectric film, and between the second dielectric film and the fourth dielectric film is established, nd+n'd&#x2032;=p&#x3bb;/4, where p is an integer, and &#x3bb; is oscillation wavelength of a laser beam generated by the semiconductor laser device.

Semiconductor laser device having a low reflection film of stable reflectance

A low reflective film is formed of, in sequence from a side in contact with a laser chip, a first dielectric film of a refractive index nand a thickness d, a second dielectric film of a refractive index nand a thickness d, a third dielectric film of a refractive index nand a thickness d, and a fourth dielectric film of a refractive index nand a thickness d, specifically, aluminum oxide AlOwith a refractive index n=1.638 is used for the first dielectric film, silicon oxide SiOwith a refractive index n=n=1.489 for the second and fourth dielectric films, tantalum oxide TaOwith a refractive index n=2.063 for the third dielectric film, respectively, resulting in a semiconductor laser device with a reflectance which is stably controllable.

Semiconductor laser devices

A semiconductor laser device includes a dielectric multilayer film with a reflectance of 40% or more, on at least one of optical exit faces of a laser chip. The dielectric multilayer film includes a film of tantalum oxide (TaO) and another film of a dielectric oxide, such as aluminum oxide (AlO), and silicon oxide (SiO). The tantalum oxide film has an optical absorption coefficient smaller than that of silicon (Si) and thermal stability in emission superior to that of titanium oxide (TiO), thereby remarkably improving the catastrophic optical damage degradation level of the laser chip.

A nonreflective film includes films having refractive indices higher than 1 and a high-refractive index film (first film, third film, fifth film) and a low-refractive index film (second film, fourth film, sixth film, seventh film) respectively having refractive indices higher and lower than the square root of an effective refractive index of a semiconductor laser. The films have least three different compositions. Each film has a single composition. The films bring a real part and an imaginary part of an amplitude reflectance to zero, as a whole. Therefore, a semiconductor optical device with an improved degree of freedom in design of the nonreflective film is provided, even when a total thickness of the films is different from one quarter wavelength of the incident light.

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Hyogo, Japan

Hiromasu Matsuoka