Abstract: Disclosed is a high frequency optical pulse source generating stable optical pulses over a wide current range in an optical transmission system to enhance stability and reliability, the high frequency optical pulse source implementing, in one chip, a multi-section distributed feedback (DFB) laser diode with a phase control section arranged between two DFB laser diodes. By controlling the current applied to the electrode of the phase control section while applying currents to the first and second DFB sections, the present invention causes self-mode locking between the compound-cavity modes having similar threshold currents, thereby generating stable tens GHz-level optical pulses. Hence, the present invention generates optical pulses uniformly over a wide current range, thereby enhancing the stability and reliability of the element.

Abstract: Disclosed is a method for the fabrication of a spot-size converter with a lateral-tapered waveguide (or an active layer), which utilizes a mask during a lithographic process wherein the mask has a pad that can absorb strain to be occurred during forming a lateral-tapered waveguide pattern at its distal end and the lateral-tapered waveguide is fabricated by forming the distal end on the order of about 0.6 &mgr;m in width followed by forming the lateral-tapered waveguide on the order of 0.1 &mgr;m using an wet etching. Thus, it is possible to reduce a fabrication cost because it is free from a high-resolution electron beam lithography and a stepper, and hence enhance a reproducibility of the lateral-tapered waveguide because it is free from an excessive wet etching during the use of a contact exposure equipment.

Abstract: A semiconductor optical device with a differential grating formed by a holography method and a method for manufacturing the same are provided. The provided semiconductor optical device includes an n-type InP substrate, a stack structure on the InP substrate having a waveguide and active layers, a first grating formed under the stack structure and on the InP substrate, and a second grating formed on the stack structure. The provided method for manufacturing the semiconductor optical device forms a first grating on the n-type InP substrate and under the active layer, and forms a second grating on the active layer. The first and second gratings are formed by the holography method.

Abstract: The present invention relates to a method of manufacturing a semiconductor optical device. The present invention discloses a method of manufacturing an optical device of a planar buried heterostructure (PBH) type by which an active layer region of a taper shape at both ends is patterned, an undoped InP layer is selectively grown in order to reduce the propagation loss and two waveguides are simultaneously formed by means of a self-aligned method, thus simplifying the process to increase repeatability and yield.

Abstract: Disclosed is a method for the fabrication of a spot-size converter with a lateral-tapered waveguide (or an active layer), which utilizes a mask during a lithographic process wherein the mask has a pad that can absorb strain to be occurred during forming a lateral-tapered waveguide pattern at its distal end and the lateral-tapered waveguide is fabricated by forming the distal end on the order of about 0.6 &mgr;m in width followed by forming the lateral-tapered waveguide on the order of 0.1 &mgr;m using an wet etching. Thus, it is possible to reduce a fabrication cost because it is free from a high-resolution electron beam lithography and a stepper, and hence enhance a reproducibility of the lateral-tapered waveguide because it is free from an excessive wet etching during the use of a contact exposure equipment.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.

Abstract: A 0.98 &mgr;m semiconductor laser of a ridge waveguide (RWG) structure includes: to be lengthen the durability of a semiconductor laser by increasing a catastrophic optical damage (COD) level, a ridge having a fixed width and length so that the strip may stop in the position of 30 &mgr;m on the basic of end portion of an output facet along length direction of a resonator; and a non-waveguide region in the end portion of both sides of a resonator.

Abstract: A method of fabricating a semiconductor laser comprises the steps of sequentially depositing a lower cladding layer, an active layer, a first upper cladding layer, an etching stop layer, a second upper cladding layer and an ohmic contact layer over a compound semiconductor substrate, forming an etching mask over the ohmic contact layer so as to expose channel regions and to shield the ridge regions between the channel regions, performing wet etching to etch the ohmic contact layer and the second upper cladding layer so as to expose the etching stop layer so as to form the channels and the ridges having narrower widths than the parts of the etching mask shielding the ridge regions, and implanting dopant ions into the parts of the first upper cladding layer and the active layer below the channels to form ion-implanted regions by using the etching mask as the ion implantation mask.

Abstract: The present invention relates to high power semiconductor laser device and method for fabricating the same utilizing ion implanting process, by which a beam steering phenomenon of an optical output due to filaments is eliminated. This elimination is achieved by a periodically varying gain given for a resonator of the semiconductor laser device. That is, this invention changes a gain distribution which causes the generation of filaments in the resonator into different distribution. According to the present invention, there is formed an insulation layer through ion implantation to an active layer to adjust current density implanted to the active layer, thereby eliminating non-uniform distribution of the light along the longitudinal direction of the resonator.

Abstract: Disclosed is a method for fabricating a planar buried heterostructure laser diode, comprising the steps of sequentially forming a first clad layer, an undoped active layer and a second clad layer on a substrate so as to complete a first crystal growth; forming a patterned mask layer on the second clad layer; non-selectively etching the second clad layer, the active layer, the first clad layer and the substrate using the mask layer as an etching mask; selectively etching the substrate and the first and second layers; sequentially forming a first and second current blocking layers on a structure formed by the selective etching step so as to complete a second crystal growth; sequentially forming a third clad layer and an ohmic contact layer thereon after removal of the mask layer so as to complete a third crystal growth; and forming a first electrode on a rear surface of the substrate and forming a second electrode on a surface of the third clad layer.

Abstract: A method for manufacturing the semiconductor laser device comprising the steps of sequentially forming an active layer, a photo-waveguide layer, a cladding layer, and an ohmic contact layer on an upper surface of an InP substrate; forming a first patterned dielectric layer on the ohmic contact layer; depositing a patterned photoresist on the ohmic contact layer to define a p- electrode stripe layer; forming the p- electrode stripe layer only on a part of the ohmic contact layer; performing an annealing process; etching back the layers until the photo-waveguide layer is exposed, using the first patterned dielectric layer and the p- electrode stripe layer as an etching mask, to form a ridge; depositing a second dielectric layer on the substrate formed thus; selectively removing the second dielectric layer to form a contact hole on the p- electrode stripe layer; coating a bonding pad metal layer on the second dielectric layer and in the contact hole; and coating an n- electrode metal layer on bottom surface of t