Nippon Electric Co., Ltd.

Nippon Selfoc Co., Ltd.

Hiroo Yonezu

Masayasu Ueno

Izuo Hayashi

Tonao Yuasa

Isamu Sakuma

Katsuhiko Nishida

Roy Lang

Yasuo Nannichi

Tsuneo Shinohara

Taibun Kamejima

Toshio Uji

A stripe-shaped excitation region is provided in an active layer of a double heterojunction laser device, the excitation region and the other region of the active layer being endowed with an effective refractive index difference or optical absorption coefficient difference therebetween, and a carrier injection region is provided contiguously to the excitation region, whereby the laser device exhibits a low ohmic resistance, effects a stable lower-order transverse mode oscillation and suppresses relaxation oscillations. By preventing the stripe-shaped excitation region and the carrier injection region from being exposed to reflective surfaces, the aforecited beneficial results can be realized over a wide range of operating currents, and a laser device of extremely high power density emission is achieved due to the increase of the threshold of the catastrophic optical damage on mirrors.

Stripe-geometry double heterojunction laser device

A semiconductor laser having a double heterostructure configuration is provided with a light waveguide layer extending between a pair of mirrors. A thin active layer is disposed adjacent to the waveguide layer, and is formed in the shape of a stripe having a width of approximately 5 .mu.m. The stripe is shorter in axial length than the waveguide, such that the ends of the stripe are spaced from the mirrors by a distance of 30 to 60 .mu.m.

Injection-type semiconductor laser

A device for coupling a laser beam to an end surface of an optical fiber comprises a beam converging lens, a holder for the fiber, a block of a solid material, and a mass of a binder between the block and the end surface and between the block and the holder. The lens and the holder are fixed to each other so as to make the laser beam focus on the end surface. Use is preferred of an arrangement comprising a first and a second holder in which the holders have axial lines, respectively, and hold a laser element for the laser beam and the lens with a beam axis of the laser beam and an optical axis of the lens rendered coincident with the respective axial lines and in which the holders are fixed to each other with the axial lines aligned. The arrangement is effective also in coupling the laser beam to a general transmission medium. Instead of using the arrangement, a lens holder may be fixed to the fiber holder and then to a laser element holder so as to make the laser beam focus on the optical fiber end surface. A nonreflecting coating is desirable on the block at a portion exposed to the incident laser beam either when the laser beam is incident onto the block with a small angle of convergence or when the block is thin. The solid material, the binder, and the optical fiber usually have an approximately equal refractive index.

Device for excellently coupling a laser beam to a transmission medium

In a double heterojunction semiconductor laser, extremely high optical power density emission is achieved by forming a stripe-geometry exciting region in an active layer so as not to be exposed on the opposite reflective surfaces, and selecting a band gap of the stripe-geometry exciting region narrower than that of surrounding non-exciting region of the active layer. A pair of window regions formed between the respective reflective surfaces and the tip ends of the stripe-geometry exciting region are sandwiched between a pair of heterojunction interfaces and thus acting low loss optical waveguides. In addition, by providing an optical obstacle region in the vicinity of the window region, higher order modes in horizontal transverse mode oscillations are suppressed, and thereby extremely high optical power output at the fundamental mode can be obtained without causing catastrophic optical damage on the reflective surfaces.

Stripe-geometry double heterojunction laser element

In a semiconductor laser element, a semiconductor laser crystal having a pair of reflection surfaces and a pair of opposing principal surfaces is fused to a heat sink having a planar surface wider than each of the principal surfaces by a layer formed of a fusible metal on the planar surface, whereby one of the ohmic contacts formed on predetermined areas of the principal surfaces is brought into contact with a predetermined portion of the fusible metal layer. A unitary film of an electrically insulating material, such as silicon monoxide, silicon dioxide, silicon nitride, and/or aluminium oxide, is sputtered or otherwise formed continuously on the reflection surfaces and on the exposed portion of the fusible metal layer left uncovered by the laser crystal fused to the heat sink. After the unitary film is formed on the other of the contacts, it is still possible to bond a metal lead directly to the other contact by employing an ultrasonic bonding technique. The fusible metal may be indium, tin, a solder, or a gold-tin, gold-silicon, or gold-germanium alloy, all of which are fusible at a temperature below about 370.degree. C. The laser crystal may be a double or single heterojunction or a homojunction crystal of lead sulfide or telluride or an intermetallic compound, such as GaAs-Al.sub.x Ga.sub.1-x As. The heat sink may be made of silicon, diamond of the IIa type, or copper.

Semiconductor laser element having a unitary film on a laser crystal and

A semiconductor laser device in which at least one of the main surfaces of a semiconductor laser crystal body which generates heat during operation is brought into thermal contact with a silicon crystal heat-sink body.

Semiconductor laser device equipped with a silicon heat sink

A hermetically sealed injection semiconductor laser device includes a hollow cylinder in which a crystal laser pellet is enclosed. The ends of the cylinder are sealed by metal electrodes one of which projects axially into the cylinder and is connected to an electrode surface of the crystal pellet. A lens element is disposed within the cylinder.

Hermetically-sealed injection semiconductor laser device

A semiconductor laser device includes a narrow elongated semiconductor region of the same conductivity type as another semiconductor region lying in the vicinity of the active region of the laser device. The elongated region extends in depth from the surface of the device to the vicinity of the active region. A surface semiconductor layer of an opposite conductivity type covers the entire surface of the device except for the elongated region.

Double heterostructure stripe geometry semiconductor laser device

An injection semiconductor laser having an active region normal to the reflecting surfaces includes an ohmic metal film on the side of the heat sink near the active region. The ohmic metal film is plated with a layer of a thermally conductive material. The shape and dimensions of the plated layer are selected to protect the laser from being damaged when the laser device is bonded to the heat sink, and also to prevent light rays emerging through one of the reflecting surfaces from impinging on the surface of the heat sink.

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Tokyo, Japan

Hiroo Yonezu