Abstract: A set of semiconductor laser elements and manufacturing method. The set of semiconductor laser elements have mutually different oscillation wavelengths, and perform single longitudinal mode oscillation by having periodically varying refractive index within the elements. The set of semiconductor laser elements are formed together from one semiconductor substrate. Duty cycle of a diffraction grating in each element differs from each other corresponding to the oscillation wavelength to realize equal coupling coefficient. Alternatively; a product of coupling coefficient and the length of area in which the diffraction grating is formed or a product of coupling coefficient and the length of the element is made substantially constant.

Abstract: An integrated semiconductor laser produced by forming waveguide layers each having a particular band gap and a particular layer thickness collectively and then forming an InP current blocking layer is disclosed. After an InGaAsP layer has been formed on an InP substrate, a waveguide including a multiple quantum well active layer is formed by selective MOVPE. Then, the waveguide is buried in an InP current blocking layer. In this configuration, the current blocking layer exhibits its expected function without regard to the width of SiO2 stripes used for selective metalorganic vapor phase epitaxial growth (MOVPE). The laser is feasible for high output operation and can be produced at a high yield.

Abstract: An integrated semiconductor laser produced by forming waveguide layers each having a particular band gap and a particular layer thickness collectively and then forming an InP current blocking layer. After an InGaAsP layer has been formed on an InP substrate, a waveguide including a multiple quantum well active layer is formed by selective MOVPE. Then, the waveguide is buried in an InP current blocking layer. In this configuration, the current blocking layer exhibits its expected function without regard to the width of SiO2 stripes used for selective metalorganic vapor phase epitaxial growth (MOVPE). The laser is feasible for high output operation and can be produced at a high yield.

Abstract: There is provided an optical semiconductor device including an optical waveguide structure having a quantum well layer and an optical confinement layer as a core layer, wherein the core layer has a thickness varying in a lengthwise direction of the optical waveguide to thereby have a function of spot-size conversion, and the quantum well layer is designed to have a band-gap energy which is constant within .+-.30 meV in the direction. The above-mentioned optical semiconductor device makes it possible to an optical gain to laser oscillation wavelength over all ranges of a resonator, and hence makes it no longer necessary to form a region only for spot-size conversion (SSC). This ensures that a device length can be as small as that of a conventional laser diode. In addition, lower threshold value characteristic and high temperature operation performance could be achieved, and a yield in devices per a wafer can be significantly enhanced.

Abstract: Disclosed is an optical semiconductor device which has:an optical waveguide where a multilayer structure including an active layer is selectively grown like a stripe with both side facets provided with a specific crystalline surface; and a semiconductor current blocking structure which is formed in contact with the side facets of the optical waveguide, the optical waveguide and the semiconductor current blocking structure being formed on a main plane of a first conductivity-type semiconductor substrate; wherein the semiconductor current blocking structure comprises a bottom surface which is selectively formed to contact only the main plane near the optical waveguide.

Abstract: Disclosed is an electro-absorption type semiconductor optical modulator utilizing the Quantum Confinement Stark Effect, in which a quantum well structure introduced in its optical absorption layer is arranged to have a potential structure such that one of the electron affinity and the energy of the top of the valence band increases in the laminating direction, while the other decreases, thereby canceling the built-in field. It is intended to lower the drive voltage and to enhance an on/off ratio (extinction ratio). Thus, the absorption peak becomes narrow at a no bias state to attain a low drive voltage and an enhanced extinction ratio.

Abstract: In a method of manufacturing an optical semiconductor device having a semiconductor substrate, an optical waveguide formed by a semiconductor layer is formed on the semiconductor substrate by the use of the selective metal-organic vapor phase epitaxy including source materials. The source materials are intermittently supplied in the selective metal-organic vapor phase epitaxy.

Abstract: A pair of SiO.sub.2 stripe masks are formed on a p-InP substrate (31) with a separation of 1.5 .mu.m in ?011! direction and an optical waveguide including a p-InP clad layer (32), an active layer (33) and an n-InP clad layer (34) is formed on the p-InP substrate (31) at the 1.5 .mu.m exposed area according to MOVPE selective growth process. Both sides of the optical waveguide are buried with pnpn current blocking structure according to the MOVPE selective growth, wherein a p-InP layer (36) and n-InP layer (37) are formed, then a surface of the n-InP layer (37) is inverted to p-type to form a p-InP inversion layer (38) according to Zn open tube diffusion process carried out in MOVPE system, thereby the interconnection between the n-InP layer (37) and the n-InP clad layer (34) is prevented, and then a p-InP layer (39) and n-InP layer (40) are formed. An n-InP layer (41) is formed thereon.

Abstract: On an n-InP substrate (101), a mask (102) having a first portion (102a) and a second portion (102b) is formed. The mask (102) has a first gap (NG) at the first portion (102a). A width of the second portion (102b) is greater than a width of the first portion (102a). A core layer (120) is epitaxially grown selectively on the substrate (101) at an area corresponding to the first gap (NG). The first gap (NG) is widened and an additional gap (AG) is formed at the second portion (102b) to form a second gap (WG) comprising the first gap after widened and the additional gap (AG). A clad layer (106) is epitaxially grown on the substrate (101) at an area corresponding to the second gap (WG) so as to cover the core layer(120). A difference in width between the first portion (102a) and the second portion (102b) is set so that a thickness of the clad layer at an area corresponding to the second portion (102b) becomes equal to a thickness of the clad layer (106) at an area corresponding to the first portion (102a).

Abstract: A pair of SiO.sub.2 stripe masks are formed on a p-InP substrate (31) with a separation of 1.5 .mu.m in ?011! direction and an optical waveguide including a p-InP clad layer (32), an active layer (33) and an n-InP clad layer (34) is formed on the p-InP substrate (31) at the 1.5 .mu.m exposed area according to MOVPE selective growth process. Both sides of the optical waveguide are buried with pnpn current blocking structure according to the MOVPE selective growth, wherein a p-InP layer (36) and n-InP layer (37) are formed, then a surface of the n-InP layer (37) is inverted to p-type to form a p-InP inversion layer (38) according to Zn open tube diffusion process carried out in MOVPE system, thereby the interconnection between the n-InP layer (37) and the n-InP clad layer (34) is prevented, and then a p-InP layer (39) and n-InP layer (40) are formed. An n-InP layer (41) is formed thereon.

Abstract: The invention provides a semiconductor optical integrated device which includes (a) a semiconductor layer, (b) a plurality of masks formed on the semiconductor layer, each of the masks having a shape varying in an axial direction of a light waveguide, and (c) quantum well structure selectively grown on the semiconductor layer by metal organic vapor phase epitaxy (MOVPE). The quantum well structure includes a well layer having a thickness and a bandgap wherein at least one of the thickness and bandgap in a region is different from those in another regions, a shape of said masks in the region being different from that in the another regions. The invention provides many advantages, one of which is that light waveguides having different bandgaps from one another can be formed on a common plane by single selective growth. This makes it possible to communicate regions to one another with high optical coupling ratio.

Abstract: A semiconductor optical monolithic integration device has a semiconductor substrate including an active region and a passive region. Epitaxial layers including a multiple quantum well structure have a variation in band gap energy and thickness along a waveguide direction. The epitaxial layers in the active region are selectively grown by a metal organic vapor phase epitaxy on a first selective growth area defined by a first mask pattern provided in the active region except in the passive region. The first mask pattern has a variation in width along the waveguide direction. The epitaxial layers are simultaneously and non-selectively grown on an entire surface of the passive region by the metal organic vapor phase epitaxy and the epitaxial layers have a mesa structure in the active region and a plane structure in the passive region.

Abstract: In a fabricating method of an optical semiconductor device, a pair of SiO.sub.2 films are formed on an n-InP substrate so as to have a large width in a region I (laser region) and a small width in a region II (optical waveguide region) and have the same gap interval therebetween in the regions I and II, and then an InGaAsP optical guide layer, a MQW (multiquantum well) active layer comprising InGaAsP quantum well layers and InGaAsP barrier layers, and a p-InP layer are selectively grown by MOVPE (metal-organic vapor phase epitaxial growth) method, whereby compressive lattice strain is introduced in the InGaAsP quantum well layers of the region I, and tensile lattice strain is introduced in the InGaAsP quantum well layers of the region II.

Abstract: On an n-InP substrate (101), a mask (102) having a first portion (102a) and a second portion (102b) is formed. The mask (102) has a first gap (NG) at the first portion (102a). A width of the second portion (102b) is greater than a width of the first portion (102a). A core layer (120) is epitaxially grown selectively on the substrate (101) at an area corresponding to the first gap (NG). The first gap (NG) is widened and an additional gap (AG) is formed at the second portion (102b) to form a second gap (WG) comprising the first gap after widened and the additional gap (AG). A clad layer (106) is epitaxially grown on the substrate (101) at an area corresponding to the second gap (WG) so as to cover the core layer (120). A difference in width between the first portion (102a) and the second portion (102b) is set so that a thickness of the clad layer at an area corresponding to the second portion (102b) becomes equal to a thickness of the clad layer (106) at an area corresponding to the first portion (102a).

Abstract: A SiO.sub.2 mask is formed on an n-type InP substrate. The mask gap width is narrower in a region I (laser region) and wider in a region II (modulator region). With taking the mask as growth blocking masks, an optical guide layer of InGaAsP, an MQW active layer of InGaAs well layer and InGaAsP barrier layer, p-type InP layer are selectively grown. By removing a part of the mask, p-type InP clad layer and p-type InGaAs cap layer are formed. By this, regions having mutually different bandgap can be formed through one selective growth process. Also, it becomes possible to form the regions having large bandgap difference while avoiding lattice mismatching.

Abstract: A semiconductor optical monolithic integration device comprises a semiconductor substrate including an active region and a passive region. Epitaxial layers including a multiple quantum well structure have a variation in band gap energy and thickness along a waveguide direction. The epitaxial layers in the active region are selectively grown by a metal organic vapor phase epitaxy on a first selective growth area defined by a first mask pattern provided in the active region except in the passive region. The first mask pattern has a variation in width along the waveguide direction. The epitaxial layers are simultaneously and non-selectively grown on the entirety of the passive region by metal organic vapor phase epitaxy and epitaxial layers having a mesa structure in the active region and a plane structure in the passive region are formed.

Abstract: In a method of making a tunable twin guide (TTG) type tunable semiconductor laser, over the surface of a semiconductor substrate of one conductivity type, an active layer, a central layer of the opposite conductivity type, and a tuning layer, each being stripe-shaped and overlying the top of the preceding one is provided. This method is characterized in that the processing of semiconductor elements for defining the current path/optical waveguide inside the laser is carried out not by etching but by using selective epitaxy method such as metal organic vapor phase epitaxy (MOVPE). The use of selective MOVPE permits to form stripe-shaped layers at high precision and good uniformity, with consequent effects of minimizing scattering of laser light, increasing the efficiency of the drive power to laser light output conversion and enhancing the coupling efficiency with optical fibers. Besides thinner central layer that can be formed can contributes to enlarging the tunable bandwidth of laser light.