Kabushiki Kaisha Toshiba

Naohiro Shimada

Satoshi Komoto

Seiji Iida

Koichi Genei

Kazuo Fukuoka

Masaki Okajima

Hideaki Kinoshita

Yoshio Iizuka

Yukio Watanabe

Motoyuki Yamamoto

Nawoto Motegi

Hiroko Nagasaka

Gen-ichi Hatakoshi

Nobuyuki Matsuura

Hatsumi Kawata

Light emitting device

An InGaAlP active region,which substantially lattice-matches with a GaAs substrate,has a multiple quantum well structure (MQW) formed by quantum well layers,of InGaP. When the oscillating wavelength caused by the current injection is less than or equal to 670 nm, the thickness (Lz) of the InGaP quantum well layers,is set to be less than 8 nm to form a lattice mismatching so that the quantum well layers,have a greater lattice constant than that of the GaAs substrate,and a compressive strain is added to the quantum well layers,Thus, gain is increased by reducing the thickness of the quantum well layers,and adding the compressive strain thereto, so that it is possible to achieve the improvement of the temperature characteristics, such as a reduced threshold, an improved efficiency, and a reduced current during operation at a high temperature, in a laser having an oscillating wavelength of 650 nm.

Multiple quantum well semiconductor laser diode and DVD system using the same

An optical waveguide layer formed on a semiconductor substrate is etched to form two parallel grooves, thereby obtaining a low ridge having a relatively small height along the longitudinal direction of the grooves. Thereafter, a current blocking layer and a third cladding layer are formed. For this reason, the dimensions such as the height and width of the ridge can be controlled with high precision, and crystal growth for the current blocking layer can be relatively easily performed. Therefore, crystal defects are not concentrated near the ridge, and laser characteristic values fall within a sufficiently allowable range which cannot be obtained by the conventional laser device. A reliable laser device capable of obtaining desired laser characteristics with excellent uniformity and reproducibility can be obtained.

Semiconductor laser device having uniform and reproducible laser

A semiconductor laser device for oscillating laser beams having different wavelengths from adjacent regions includes an n-type first cladding layer, a first active layer, a p-type second cladding layer, a p-type first contact layer, a p-type third cladding layer, a second active layer, an n-type fourth cladding layer, and an n-type second contact layer in this order from an n-type substrate. The first and second electrodes are arranged on the first and second contact layers, respectively, and the third electrode is arranged on the lower surface of the substrate. A difference in energy gaps of the second cladding layer and the first contact layer is so large that no current flows across the second cladding layer and the first contact layer, and a difference in energy gaps of the third cladding layer and the first contact layer is so large that no current flows across the third cladding layer and the first contact layer. P-type intermediate energy-gap layers are formed into stripes between the second cladding layer and the first contact layer and between the third cladding layer and the first contact layer, respectively, and current paths are respectively formed through the intermediate energy-gap layers. The two current paths are substantially aligned to each other in a vertical direction.

Integrated semiconductor laser device

A semiconductor laser device comprises a substrate formed of elements of the III-V groups and having one conductivity type, a lower clad layer formed on the substrate and having the same conductivity type as that of the substrate, and an upper clad layer formed on the lower clad layer and having a conductivity type opposite to that of the lower clad layer. A waveguide layer having a large refractive index is formed within the lower clad layer by decreasing the band gap of the upper clad layer. The light generated in an activation layer is guided to the lower clad layer, so as to suppress adverse effects which the upper clad layer may have on element characteristics.

Semiconductor laser device

A semiconductor laser diode includes two semiconductive cladding layers of different conductivity types, which are stacked on a substrate. An active layer of an undoped semiconductor film is sandwiched between the cladding layers. A channel groove is formed in a current blocking layer and the underlying cladding layer, to be deep enough to cause the current blocking layer to be divided into two parts. A waveguide layer covers the channel groove and the current-blocking layer, to provide a slab-coupled waveguide structure for transverse mode oscillation. The second cladding layer, the current-blocking layer, and the waveguide layer are composed of gallium arsenide containing aluminum.

Transverse-mode stabilized semiconductor laser diode with slab-coupled

A hetero junction type semiconductor laser device is provided wherein a hetero layer is formed on a clad layer leaving a stripe shape portion. The clad layer is formed on an active layer over a substrate. At least two coating layers of the same conductivity type as the clad layer are formed on the hetero layer so as to have a current confining effect and a built-in waveguide effect. The refractive index of the coating layers which is nearer to the active layer is greater than the refractive index of the clad layer and the refractive index of the other coating layer is smaller than the refractive index of the coating layer which is nearer to the active layer. Using this construction, a low lasing threshold current is achieved.

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Kawasaki, Japan

Naohiro Shimada