Abstract: The invention provides a semiconductor laser module and an optical transmission system, with which noise caused by light reflected back from a transmission path can be suppressed. The semiconductor laser module, includes a package having a window, a semiconductor laser chip outputting light, a lens that is optically designed such that it couples the light that is output by the semiconductor laser chip into an optical transmission path, an optical isolator that is disposed between the lens and the window, a temperature control mechanism for keeping temperature of these components constant, and a tubular ferrule that is holds and covers the optical transmission path. The semiconductor laser chip, the lens, the optical isolator, and the temperature control mechanism are arranged inside the package. A polarizer is arranged at an end face of the ferrule on the side of the package, such that the polarizer matches a polarization plane of the light that is emitted through the window of the package.

Abstract: A semiconductor laser includes a substrate of a first conductive type, a mesa provided on the substrate and having a multilayered structure including at least a cladding layer of the first conductive type, an active layer and another cladding layer of a second conductive type, a current blocking layer provided on both sides of the mesa, a buried layer of the second conductive type provided on the mesa and the current blocking layer, and a contact layer of the second conductive type provided in a predetermined region on the buried layer. The predetermined region does not include a portion immediately above the mesa.

Abstract: A semiconductor laser includes a substrate of a first conductive type, a mesa provided on the substrate and having a multilayered structure including at least a cladding layer of the first conductive type, an active layer and another cladding layer of a second conductive type, a current blocking layer provided on both sides of the mesa, a buried layer of the second conductive type provided on the mesa and the current blocking layer, and a contact layer of the second conductive type provided in a predetermined region on the buried layer. The predetermined region does not include a portion immediately above the mesa.

Abstract: The optical fiber amplifier of this invention includes plural pump light sources for emitting pump light; a first wavelength multiplexer for receiving the pump light emitted by the pump light sources at plural input ports and wavelength multiplexing the received pump light, so as to generate wavelength multiplexed pump light and output the wavelength multiplexed pump light from an output port; a second wavelength multiplexer for receiving the wavelength multiplexed pump light at a first input port and receiving signal light at a second input port, so as to generate coupled light by coupling the wavelength multiplexed pump light and the signal light and emit the coupled light from an output port; and a rare earth-doped optical fiber for receiving the coupled light emitted from the output port of the second wavelength multiplexer and amplifying the coupled light.

Abstract: A semiconductor light emitting element includes a p-type electrode which in turn includes a contact electrode layer including at least a Pt layer. Particularly, the semiconductor light emitting element further includes a layered structure including at least an n-type cladding layer, an active layer, and a p-type cladding layer; and a p-type contact layer formed above the layered structure, and the contact electrode layer is formed on the p-type contact layer.

Abstract: An n-InP buffer layer 102, an InGaAsP active layer 103, a p-InP cladding layer 104 and a p-InGaAsP surface protective layer 105 are successively epitaxially grown on an n-InP substrate 101 having a (100) plane as a main plane. An etching mask 106, an insulating film, is formed in a stripe in the <011> direction by photolithography and dry etching. Using a solution comprising a mixture of hydrochloric acid, oxygenated water and acetic acid, the n-InP buffer layer 102 is etched to a depth lower than the p-InP cladding layer 103, to form a mesa stripe 107. Next, the insulating film 106 is removed and the p-InGaAsP surface protective layer 105 is removed using a solution comprising a mixture of sulfuric acid and oxygenated water. Thereafter, InP current blocking layers 108 and 109 are selectively formed at the regions other than the mesa stripe 107 by the liquid-phase epitaxial growth. Thus, a buried heterostructure semiconductor laser is fabricated, having good laser characteristics and a high reliability.