摘要:
An optical modulating device is disclosed which has, on a substrate directly or via a lower cladding layer, an optical waveguide layer, an upper cladding layer of a refractive index smaller than that of the optical waveguide layer and a pair of electrodes for applying an electric field across the substrate and the upper cladding layer and in which the absorption coefficient for incident light of a fixed intensity incident to the optical waveguide layer is varied by the electric field applied across the pair of electrodes to perform the modulation of the light and the modulated light is emitted from a light emitting end face of the optical waveguide layer. In accordance with the present invention, a pn junction is formed in the upper cladding layer and at least one buffer layer of an energy gap smaller than that of the upper cladding layer but larger than that of the optical waveguide layer is interposed between the upper cladding layer and the optical waveguide layer.
摘要:
An optical modulation device is disclosed in which a difference between the photon energy of incident light and the band-gap energy of the modulation waveguide layer is set to a value greater than 50 meV to thereby suppress the degradation of the modulation voltage and the modulation band width which is caused by an increase in the intensity of incident light and in that the optical modulation device is formed in a predetermined length to thereby decrease the modulation voltage. The energy gap of the optical waveguide layer of the optical modulation device is varied continuously or discontinuously in the direction of its thickness to provide a constant absorption coefficient thickwise of the optical waveguide layer so that the electric field intensity distribution in the optical waveguide layer is compensated for, by which overlap of the light distribution and the absorption coefficient is increased so as to decrease the modulation voltage and broaden the modulation band by the reduction of the length of the device. The composition, thickness and stripe width of the optical waveguide layer are changed so that its absorption coefficient increases from the light receiving end face of the optical waveguide layer toward its light emitting end face, thereby making the number of carriers absorbed per unit length substantially constant in the direction of travel of light.
摘要:
An optical modulation element is disclosed which has, on a substrate directly or through a lower clad layer, an optical waveguide layer of a low impurity concentration, an upper clad layer of a refractive index smaller than that of the optical waveguide layer, and electrodes, and in which light of a constant intensity incident on a light incident end face of the optical waveguide layer is intensity-modulated by changing the absorption coefficient of the optical waveguide layer by means of an electric field applied thereto across the electrodes so that the thus modulated light is emitted from a light emitting end face of the optical waveguide layer. In accordance with the present invention, a plurality of low impurity concentration regions and a plurality of high impurity concentration regions are disposed alternately with each other in contact with at least one of the lower and upper clad layers in the direction of travel of light in such a manner that the distribution density of the plurality of high impurity concentration regions increases in the direction of travel of light.
摘要:
A semiconductor integrated light emitting device is disclosed which comprises a light emitting waveguide including a light emitting layer, and an external waveguide directly coupled to the light emitting waveguide. In accordance with the present invention, the light emitting waveguide and the external waveguide are mutually laminated in the vicinity of a region where they are directly coupled together.The intensity of the optical output from the light emitting waveguide is modulated in the external waveguide by the electroabsorption effect.
摘要:
An optical communication system of a construction wherein the average wavelength dispersion value of the transmission optical fiber used, the optical output intensity of each optical amplifier repeater inserted in the transmission optical fiber and the widths of return-to-zero optical pulses transmitted over the transmission line are determined so as to compensate for the pulse compression effect by the nonlinear optical effect produced on the optical pulses by the pulse spreading effect by the wavelength dispersion effect. An optical multiplexer in the optical transmitting device time-division multiplexes the return-to-zero optical pulses, and the optical multiplexed signal is provided as an alternating-amplitude optical signal with the amplitudes of the return-to-zero optical pulses alternated.
摘要:
An optical semiconductor device manufacturing method is disclosed which involves an ion implantation step of implanting ions into a compound semiconductor wafer through an ion implantation mask and an annealing step of activating atoms in the compound semiconductor wafer through an annealing mask film. The ion implantation step and the annealing step are performed in succession after laminating mono- or multi-layered compound semiconductor layers as the ion implantation mask and the annealing mask film on the compound semiconductor wafer.
摘要:
An avalanche photodiode with a quantum well layer in which a thin film, periodic multilayer structure composed of two different semiconductors is formed in a carrier multiplying region, the effective ionization coefficient ratio of carriers is raised by a quantum well layer formed by the thin film, multilayer periodic structure, and only electrons of large ionization coefficient are injected into the multiplying region, thereby to reduce noise in the APD.
摘要:
A semiconductor device, which is formed by a sequential lamination of a first semiconductor layer having a carrier concentration more than 10.sup.17 cm.sup.-3, a second semiconductor layer having a carrier concentration less than 10.sup.16 cm.sup.-3, a third semiconductor layer having a carrier concentration more than 10.sup.17 cm.sup.-3 and a thickness less than 300 .ANG., a fourth semiconductor layer having a carrier concentration less than 10.sup.16 cm.sup.-3, and a fifth semiconductor layer having a carrier concentration more than 10.sup.17 cm.sup.-3 and, in which the first and fifth semiconductor layers are the same in conductivity type and the third semiconductor layer is different in conductivity type from the fifth semiconductor layer. In accordance with the present invention, the energy gap of the third semiconductor layer is larger than the energy gaps of the second and fourth semiconductor layers. An annular region of a semi-insulating material or of the same conductivity type as that of the third semiconductor layer may be formed around an active region to extend from the fifth semiconductor layer to the second semiconductor layer.
摘要:
A method for manufacturing diffraction grating, in which after forming, on a substrate, one of a negative type photoresist film (an N film) and a positive type photoresist film (a P film) to cover a first region A and the other of the negative type photoresist film and the positive type photoresist film, or the latter film on the former one to cover a second region B, the first region and the second region are subjected to two-beam interference exposure, thereby forming a diffraction grating in which corrugations in the first region and the second region are reverse in phase to each other, through utilization of characteristics of the negative type photoresist film and the positive type photoresist film. Another feature of the present invention resides in that after forming, on a substrate, a structure in which a negative type photoresist film (an N film) is formed to cover only a first region A and the negative type photoresist film is formed on a positive type photoresist film (a P film) to cover a second region B, the first region and the second region of the substrate are subjected to two-beam interference exposure, thereby forming a diffraction grating in which corrugations in the first region and the second region are reverse in phase to each other, through utilization of characteristics of the negative type photoresist film and the positive type photoresist film.
摘要:
A quantum well structure is disclosed, which is comprised of a quantum well layer of a thickness substantially equal to the de Broglie wavelength of electrons and carrier confinement layers of an energy gap greater than that of the quantum well layer. A second material of a lattice constant different from that of a first material primarily for the quantum well layer is disposed in the quantum well layer to provide a phase shift in the period of the crystal lattice of the first material, thereby forming energy levels in the forbidden band of the quantum well layer. A semiconductor device which employs such a quantum well structure and is so constructed as to utilize its physical phenomenon which is caused by the energy levels in the forbidden band. In concrete terms, the present invention has its feature in allowing ease in the fabrication of an intermediate infrared or blue light emitting device, for instance.