Abstract: A rod lens or a cylindrical lens is disposed in front of a semiconductor laser to increase a divergence angle of a laser beam emitted from the semiconductor laser so as to form a substantially circular far field pattern. In another constitution, there is disposed in front of a semiconductor laser a composite lens having two cylindrical surfaces whose cylindrical axes are perpendicular to each other. The cylindrical surface on the side of the semiconductor laser is a convex surface and the other cylindrical surface is a convex or concave surface. In still another constitution, two semiconductor lasers emitting the same optical signal are arranged adjacent each other so that respective light emitting portions of two pn junction planes are located in the same plane and perpendicular to each other, and that laser beams form orthogonal spots at a single predetermined position.

Abstract: A light source unit of the present invention is provided with a plurality of semiconductor lasers each emitting one laser beam, a bar body to which the semiconductor lasers are attached so that p-n junctions planes of respective semiconductor lasers are arranged in the same direction, and a beam restricting plate where holes for passing a part of the beam from the semiconductor laser are formed so as to correspond to the semiconductor lasers. With this feature, a plurality of laser beams of uniform optical power can be emitted at predetermined spaces.

Abstract: An optical fiber receptacle has a glass rod lens in its one end side and a front end of an optical fiber to be connected to the opposite end side of the receptcle is brought into physical contact with a spherical surface of the glass rod lens to thereby make the optical fiber optically couple with an optical element to be provided on the glass rod lens side, wherein a housing including a sleeve for insertion of the front end of the optical fiber therein is fixed to a lens holder for fixedly holding the glass rod lens by fusion so that the center of the sleeve and the center of the spherical surface of the glass rod lens are aligned.

Abstract: A semiconductor laser is inserted into a first hole of a fixing member. An optical system including a cylindrical lens barrel and a lens attached inside the lens barrel is inserted into a second hole in order to direct a light beam emitted from the semiconductor laser to a predetermined position. The first and second holes are formed to be opposite to each other and are arranged on the same axis. The semiconductor laser and the optical system inserted into the first and second holes, respectively, so as to be partly exposed are fixed by laser welding at entrances of the first and second holes. The fixing member is provided with a third hole vertically penetrating the second hole. An adhesive is filled into the third hole. Further, an adhesive is applied onto laser welding points at the entrance of the first hole.

Abstract: A laser diode and a lens are fixed onto a laser fixing member. A laser beam emitted from the laser diode passes through the lens, and a part of the laser beam passes through a pinhole provided to a beam restricting plate. The pinhole is formed so that its diameter is smaller than the laser beam diameter at the beam restricting plate. The laser beam is transmitted therethrough while being diffracted.

Abstract: An optical branching and coupling device is provided in which the loss of light in receiving and in transmission is substantially reduced while at the same time the wavelength-branching characteristic is remarkably improved.

Abstract: A laser diode is provided which includes a substrate, a laser diode chip bonded on the substrate through a sub-mount, and a monitor element formed on the sub-mount. A space between a rear cleavage face of the laser diode chip and the surface of the monitor element is connected by a solid state waveguide, and the surface of the solid state waveguide is covered by a light reflecting resin layer.

Abstract: An optical pick-up is arranged to detect information recorded on an optical disk by causing laser light projected onto and reflected from a signal surface of the optical disk disposed within an optical system and the laser light is received by a light receiving element provided in the optical system. The optical pick-up is mounted with a laser diode unit which includes a metallic substrate, a laser diode, a photo-diode, a current feeding lead portion to the laser diode and a current output lead portion which forms the photo-diode, respectively disposed at one side face in the direction of thickness of the metallic substrate for emitting the laser light. The laser diode unit is positioned and fixed at a predetermined position of the optical system through a mounting member.

Abstract: A laser diode, which includes a substrate, a laser diode chip bonded on the substrate through a sub-mount, and a monitor element formed on the substrate, monitors laser light emitted from a rear cleavage face of the laser diode chip. The laser diode chip has its front cleavage face covered by a transparent resin. As a result, variations of the surface state of the front cleavage face are prevented.

Abstract: In an optical pick-up arranged to detect information recorded on an optical disk by causing laser light projected onto and reflected from a signal surface of the optical disk disposed within an optical system, to be received by a light receiving element provided in the optical system, a method of mounting onto the optical pick-up is provided with a laser diode unit which includes a metallic substrate, a laser diode, a photo-diode, a current feeding lead portion to the laser diode and a current output lead portion from the photo-diode, respectively disposed at one side face in the direction of thickness of the metallic substrate for emitting the laser light. The laser diode unit is positioned and fixed at a predetermined position of the optical system through a mounting member. The mounting method of the laser diode unit includes the steps of setting the other side face in the direction of thickness of the substrate and the mounting member in a desired positional relation for contact with each other.