Mitsubishi Denki Kabushiki Kaisha

Akira Takemoto

Etsuji Omura

Hitoshi Watanabe

Katsuhiko Goto

Shogo Takahashi

Syoichi Kakimoto

Masatoshi Fujiwara

Harumi Namba

Kimio Shigihara

Yutaka Nagai

Tatsuya Kimura

Yutaka Mihashi

Tohru Takiguchi

Yasuaki Yoshida

Takushi Itagaki

Tomoko Kadowaki

Ryoichi Hirano

Yoriko Tanigami

Kisuke Matsumoto

A method of making a semiconductor optical device, including an integrated laser diode and optical waveguide lens with a continuous resonator extending along a resonator length direction between a pair of resonator facets, includes forming a pair of dielectric films disposed on a surface of a substrate on which a semiconductor layer of the optical waveguide is to be grown, the dielectric films having a linear symmetry about a hypothetical line extending in the resonator length direction, having edges opposing each other and parallel to the hypothetical line, and widths perpendicular to the resonator length direction that gradually narrow toward one facet from a position in the resonator length direction of the films. A mask pattern that produces a precise layer thickness profile is easily designed.

Method of fabricating semiconductor optical device

An optical integrated circuit device includes a compound semiconductor substrate, a semiconductor laser including a compound semiconductor layer, a waveguide of a compound semiconductor layer having the same energy band gap as that of the semiconductor laser, a semiconductor amplifier having the same energy band gap as that of the semiconductor laser, a common electrode disposed on the rear surface of the substrate, a semiconductor laser electrode for current flow between the laser electrode and the common electrode so that the current is injected into the laser, a waveguide electrode for current flow between the waveguide electrode and the common electrode so that the current is injected into the waveguide, and a semiconductor amplifier electrode for current flow between the amplifier electrode and the common electrode so that the current is injected into the amplifier. Therefore, the compound semiconductor layers constituting the semiconductor laser, the waveguide, and the amplifier are grown as a single layer and the optical integrated circuit device is easily fabricated, and an absorption loss in the waveguide is suppressed by applying a voltage across the common electrode and the waveguide electrode to inject current into the waveguide.

Optical integrated circuit device and driving method therefor

In a semiconductor laser module, a semiconductor laser element is disposed on a side surface of a submount perpendicular to a front surface of a pedestal. The semiconductor laser element, the submount, a lens, and an optical fiber are positioned on the front surface of the pedestal so that laser light emitted from the semiconductor laser element is applied through the lens to a prescribed portion of the optical fiber with high reliability. Positioning of the laser element in the direction perpendicular to the front surface of the pedestal is facilitated, and positioning accuracy is improved, resulting in a low-cost and high-performance semiconductor laser module.

Semiconductor laser module and method of assembling semiconductor laser

A semiconductor laser device includes a ridge waveguide having two side surfaces, a crystalline burying layer disposed at both side surfaces of the ridge waveguide, and a second conductivity type contact layer disposed on the burying layer and the ridge waveguide. The burying layer includes a first conductivity type first current blocking layer in contact with the side surfaces of the ridge waveguide, a second conductivity type second current blocking layer disposed on a portion of the first current blocking layer and separated from the ridge waveguide by a portion of the first current blocking layer near the ridge waveguide, a first conductivity type third current blocking layer disposed on a portion of the first current blocking layer near the ridge waveguide and on the second current blocking layer, and a second conductivity type final burying layer disposed on the third current blocking layer. In this structure, there is no pn junction at a regrowth interface between the final burying layer and the contact layer so that reduction in the forward voltage of the pn junction in continuous operation is avoided and increasing leakage current is suppressed so that the threshold current and light output of the laser do not deteriorate over time.

Semiconductor laser device

A semiconductor laser device includes semiconductor layers including an active layer and cladding layers sandwiching the active layer and current injecting structure for regulating a region in the active layer into which current is injected. A light confinement coefficient in the current injection region perpendicular to the active layer is smaller than a light confinement coefficient in the same direction of a saturable absorption region. The function of the saturable absorption region is enhanced and pulsation oscillation can be produced at a high power light output.

A semiconductor light emitting device includes a semiconductor light emitting element mounted on a package stem via a radiating heatsink block, the light emitting point of the light emitting element being positioned on the central axis of the stem and at or near the center of mass of the heatsink block. Another light emitting device includes a light emitting element mounted on a stem via a heatsink block, the light emitting point of the element being positioned on the central axis of the stem with only a portion of a lower surface of the heatsink block close to the central axis of the stem attached to the stem. The movement of the light emitting point with temperature variations is suppressed. Another light emitting device includes a laser chip element mounted on a package stem via a heatsink block, the laser chip element being mounted on the heatsink block so that the emitted light forms an angle .theta. with a surface of the stem and the position and angle of the emitted light do not vary when the temperature changes.

Semiconductor light emitting device

A semiconductor laser includes a semiconductor substrate of a first conductivity type having opposite front and rear surfaces, a double-heterojunction structure including a first conductivity type lower cladding layer, an undoped active layer, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, successively disposed on the front surface of the semiconductor substrate wherein the double-heterojunction structure is a mesa having opposite sides, and a light and current confinement structure disposed on the opposite sides of the mesa for confining laser light and laser driving current within the mesa. The confinement structure includes a first conductivity type mesa embedding layer, a second conductivity type mesa embedding layer, and a semi-insulating InP layer which are successively disposed on the semiconductor substrate contacting the opposite sides of the mesa. In this structure, since the semi-insulating semiconductor layer is not in contact with the active layer, unfavorable diffusion of impurities contained in the semi-insulating layer into the active layer is prevented.

Semiconductor laser with semi-insulating current blocking layers

An optical integrated circuit includes a laser diode emitting laser light and a photodiode detecting light emitted from the laser diode on the same semiconductor substrate but not colinear and a mirror optically coupling the laser diode with the photodiode. The axes of the laser diode and the photodiode are parallel. The mirror is parallel to a laser light emitting facet of the laser diode to couple the laser diode and the photodiode. Resonator facets of the laser diode are produced by cleaving, not etching, whereby an optical integrated circuit including a laser diode having high performance and high reliability is obtained.

Mirror coupled monolithic laser diode and photodetector

A semiconductor laser includes a semiconductor substrate of a first conductivity type; a double heterojunction structure comprising a lower cladding layer of the first conductivity type disposed on the semiconductor substrate and having a first energy band gap, a band gap discontinuity reduction layer of the first conductivity type having a thickness from five to forty nanometers disposed on the lower cladding layer and having a second energy band gap, an undoped active layer disposed on the band gap discontinuity reduction layer and having a third energy band gap smaller than the first energy band gap, the second energy band gap being intermediate the first and third energy band gaps, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer and having a fourth energy band gap larger than the third energy band gap, the double heterojunction structure having a ridge shape; a current confinement structure disposed on opposite sides of the double heterojunction structure for confining current flow to the double heterojunction structure; and first and second electrodes electrically contacting the semiconductor substrate and the upper cladding layer, respectively.

Semiconductor laser

A semiconductor laser device includes a p type semiconductor substrate, an active layer having a smaller energy band gap than the p type semiconductor substrate and an n type semiconductor layer having a larger energy band gap than the active layer successively formed on the p type semiconductor substrate, a mesa formed by selectively etching the semiconductor substrate, active layer, and n type semiconductor layer, p-n-p layers having larger energy band gaps than the active layer and disposed at both sides of the mesa, a small energy band gap layer having a smaller energy band gap than the p type semiconductor substrate and disposed on the p-n-p layers, and an n type semiconductor layer disposed on the small energy band gap layer and on the n type semiconductor layer. The small energy band gap layers decrease the current flowing through the thyristor structure and are disposed close to the active region but in a different processing step from the formation of the active layer. A waveguide structure in which the active layer is surrounded by semiconductor layers having larger energy band gaps is realized.

A semiconductor laser device having an active layer sandwiched by semiconductor layers having larger energy band gaps than that of the active layer, includes a semiconductor absorption layer having an energy band gap no larger than that of the active layer and having a thickness periodically changing in the cavity length direction of the resonator, close to the active layer so that light which is generated at the active layer reaches the absorption layer, and a semiconductor refractive index matching layer, having a larger energy band gap than that of the active layer and a higher refractive index than those of the semiconductor layers sandwiching the active layer, to make the equivalent refractive indices in layer thickness direction substantially equal along the resonator direction.

Method of producing a semiconductor laser

A semiconductor optical element includes a semiconductor layer on a semiconductor substrate, a plurality of parallel stripe-shaped grooves in the layer having widths sufficiently narrow to produce a quantum effect and spaced at an interval sufficiently narrow to produce a quantum effect in a semiconductor layer disposed between adjacent grooves, and a structure including alternating semiconductor quantum well and barrier layers disposed on the semiconductor layer in which the quantum well layer thickness is less than the depth of the grooves and sufficiently thin to produce a quantum effect and the barrier layer thickness is larger than the depth of the grooves, the quantum well and barrier layers being alternatingly disposed on the semiconductor layer in the grooves and on regions between adjacent grooves.

Light interactive heterojunction semiconductor device

A semiconductor laser device having an active layer sandwiched by semiconductor layers having larger energy band gaps than that of the active layer, includes a semiconductor absorption layer having an energy band gap no larger than that of the active layer and having a thickness periodically changing in the cavity length direction of the resonator close to the active layer so that light which is generated at the active layer reaches the absorption layer, and a semiconductor refractive index matching layer having a larger energy band gap than that of the active layer and a higher refractive index than those of the semiconductor layers sandwiching the active layer to make the equivalent refractive indices in layer thickness direction substantially equal along the resonator direction.

A buried heterojunction semiconductor laser appropriate for integration with other electronic circuitry and method of producing same, in which the width of a central stripe of the active region can be reduced beyond the physical size limitations of the connecting electrode so as to allow the semiconductor laser to oscillate in a stable manner and with low threshold current. The semiconductor laser is provided with a portion of the surface of the upper cladding layer located above the disordered active layer regions electrically connected with the upper cladding layer located above the nondisordered central stripe. As a result, the central stripe electrode can be of a width larger than that of the central stripe itself.

Method of making a semiconductor laser using superlattice disordering

A semiconductor laser device of the buried heterostructure type in which leakage current is substantially reduced. A mesa portion carries the active lasing portion of the laser, and current blocking layers are grown at either side of the mesa portion. One of the current blocking layers has its conductivity type inverted to the opposite type to eliminate a current leakage path, thereby to provide a high efficiency low leakage current semiconductor laser. Conductivity inversion is accomplished by adjusting the impurity concentration levels in the layers on either side of the mesa portion, and controllably diffusing impurities from one layer to another until conductivity inversion is accomplished in a thin tip portion of one of the layers.

Growing community of inventors

Itami, Japan

Akira Takemoto