Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Yasuhiro Kunitsugu

Yasuyuki Nakagawa

Harumi Nishiguchi

Hiromasu Matsuoka

Yasuo Nakajima

Junichi Horie

Tetsuya Yagi

Hitoshi Tada

A back-surface-incidence semiconductor light element includes: a semiconductor substrate of a first conductivity type; a first semiconductor layer of a first conductivity type on the semiconductor substrate; a light absorbing layer on the first semiconductor layer; a second semiconductor layer on the light absorbing layer; and an impurity diffusion region of a second conductivity type in a portion of the second semiconductor layer. A region including a p-n junction between the first semiconductor layer and the impurity diffusion region, and extending through the light absorbing layer, is a light detecting portion that detects light incident on a back surface of the semiconductor substrate. A groove in the back surface of the semiconductor substrate surrounds the light detecting portion, as viewed in plan.

Semiconductor light detecting element with grooved substrate

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 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.

Semiconductor laser device

In a method of producing a .lambda./4-shifted diffraction grating, a positive type photoresist is applied to a substrate so that the surface level of the photoresist is in the vicinity of the node of the nodes in a standing wave light intensity distribution in the thickness direction of the photoresist that is nearest to the substrate, the light intensity distribution is produced by interference between incident light in the film and light reflected by the substrate. Then, the photoresist is subjected to two-luminous-flux interference exposure, followed by development, providing a pattern of photoresist films regions each having an over-hanging portion. Thereafter, an insulating film is deposited on the photoresist and exposed parts of the substrate, a first protective resist is selectively formed on the photoresist, the insulating film which is not covered with the first resist is removed, the substrate is etched using the photoresist, which is not covered with the first resist, as a mask, the photoresist is removed together with the first resist and the insulating film on the photoresist by lift-off, leaving the insulating film on the substrate, a second protective resist is selectively formed on the etched surface of the substrate, and the substrate is etched using the insulating film on the substrate as a mask, whereby two regions of grooves in the substrate having reversed phase are produced.

Growing community of inventors

Tokyo, Japan

Yasuhiro Kunitsugu