Abstract: A layout of a carrier in an optical component having the carrier and an optical device is described. The layout comprises a pair of terminals, a resistor connected to a first terminal, a wire bond connected in series with the resistor for connecting the resistor to an optical device, and a first ground patch connected to a second terminal and for connecting to an optical device for providing a common ground on a first surface on a substrate on which the carrier is based, whereby the pair of terminals, the resistor, the wire bond and an optical device form an optical signal transmission system in the optical component.

Abstract: A layout of a carrier in an optical component having the carrier and an optical device is described. The layout comprises a pair of terminals, a resistor connected to a first terminal, a wire bond connected in series with the resistor for connecting the resistor to an optical device, and a first ground patch connected to a second terminal and for connecting to an optical device for providing a common ground on a first surface on a substrate on which the carrier is based, whereby the pair of terminals, the resistor, the wire bond and an optical device form an optical signal transmission system in the optical component.

Abstract: An optical modulator whose cutoff frequency is not halved even in the case of differential driving, as well as a mounting substrate of such an optical modulator and a driving method of such an optical modulator. An optical modulator is configured in such a manner that two EA modulators A and B are connected in series to each other via a transparent waveguide. When voltages are applied to the two EA modulators A and B simultaneously, light that is input from an end face of the optical modulator is absorbed first by the EA modulator A and then by the EA modulator B. Therefore, an extinction ratio that is two times larger than in a conventional optical modulator can be obtained. To prevent pulse superimposition in a modulated light waveform, a line may be made longer than a line so that a drive electrical signal reaches the EA modulator B with a delay. To mount the optical modulator, flip-chip mounting with a coupled coplanar substrate and gold balls or the like may be used.

Abstract: A semiconductor laser device in which a semiconductor laser emitting laser light and a light modulator modulating the laser light are integrated on a compound semiconductor substrate, includes a hole trapping layer for suppressing a reactive current that is generated when the semiconductor laser is operated and that does not contribute to laser oscillation. The hole trapping layer has a first region in the semiconductor laser and a second region in the light modulator. The hole trapping layer has a high carrier concentration and a low resistance and is discontinuous between the semiconductor laser and the light modulator, so that isolation between the laser and the modulator is increased, whereby a high-frequency signal applied to the light modulator is prevented from flowing through the hole trapping layer into the laser.

Abstract: A semiconductor photodetector includes a semiconductor substrate of a first conductivity type; a light absorption recombination layer disposed on a front surface of the semiconductor substrate and having a band gap energy smaller than the semiconductor substrate; a first conductivity type barrier layer disposed on the light absorption recombination layer and having a band gap energy larger than the light absorption recombination layer; an undoped light absorption layer disposed on the barrier layer and having a band gap energy larger than the light absorption recombination layer and smaller than the barrier layer; an undoped window layer disposed on the light absorption layer and having a band gap energy larger than the light absorption layer; and an impurity doped region of a second conductivity type in a region extending from the window layer to the light absorption layer.

Abstract: A semiconductor device includes a laminated layer structure including at least one semiconductor layer disposed on a first conductivity type semiconductor substrate, a semi-insulating semiconductor layer disposed on the semiconductor laminated layer structure, a second conductivity type semiconductor region disposed on the front surface of the semi-insulating semiconductor layer, a first electrode on the rear surface of the substrate, and a second electrode disposed on the semi-insulating semiconductor layer and in ohmic contact with the second conductivity type semiconductor region.

Abstract: A light absorption modulator includes a semiconductor substrate of a first conductivity type; a first cladding layer of the first conductivity type disposed on the substrate; an optical waveguide disposed on the first cladding layer and including a multiple quantum well optical waveguide layer through which light travels and first and second light confinement layers respectively disposed on opposed surfaces of the optical waveguide layer to confine light in the optical waveguide layer; and a second cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the optical waveguide, one of the first and second cladding layers being n type, the one of the first and second light confinement layers that contacts the n type cladding layer being p type, and light traveling through the optical waveguide layer being modulated by applying an electric field to the optical waveguide layer.

Abstract: In an optical semiconductor device including a DFB laser and a light absorption modulator, a semi-insulating semiconductor layer is disposed between a carrier blocking layer and a upper cladding layer, the upper cladding layer having an opposite conductivity type from that of the semiconductor substrate and disposed on a buried waveguide and the carrier blocking layer. The capacitance between the carrier blocking layer and the upper cladding layer is reduced. Therefore, mutual interference between the DFB laser and the light absorption modulator through the carrier blocking layer is reduced.

Abstract: A semiconductor optical device having a small difference in level between first and second electrodes includes, at a first electrode, a junction of a p-type contact and an electron trapping semi-insulating semiconductor region in an n-type semiconductor substrate which is rectifying. At the second electrode, a diode includes a p-type window region, a light absorption region, and the n-type semiconductor substrate. When light enters this diode, a photocurrent is generated. When a bias voltage is applied to the diode in a reverse direction, the photocurrent flows between the electrodes.

Abstract: A light modulator module includes a submount; a semiconductor laser and a semiconductor light modulator having a signal input terminal integrated on the submount, the semiconductor laser outputting laser light and the semiconductor light modulator modulating the laser light in response to a high-frequency signal input to the signal input terminal; a strip line for transmitting the high-frequency signal, the strip line having first and second terminals, the second terminal receiving the high-frequency signal; a terminating resistor terminating the strip line and having opposed first and second ends with the second end being grounded; a first wire connecting the signal input terminal of the semiconductor light modulator to the first terminal of the strip line; and a second wire connecting the first end of the terminating resistor to the signal input terminal of the semiconductor light modulator.

Abstract: A semiconductor light intensity modulator utilizing the electric field absorbing effect, includes a light absorption layer which absorbs light due to the electric field absorption effect and a phase correcting semiconductor layer to which an electric field is applied independently from the light absorption layer, having a larger energy band gap than that of the light absorption layer disposed in the light waveguide path or in the vicinity thereof, of the semiconductor light intensity modulator.In this construction, by adjusting the refractive index of the phase correcting semiconductor layer and the length of the light waveguide path, the change in the refractive index in the light absorption layer can be cancelled, whereby a semiconductor light intensity modulator free of phase modulation is obtained.

Abstract: A semiconductor optical modulator includes a light absorbing layer having a multi-quantum well structure including two quantum wells including quantum well layers bounded and separated by barrier layers, the quantum wells having respective, different .DELTA.Ev/.DELTA.Ec ratios where .DELTA.Ec is the discontinuity between the barrier layer and a quantum well layer in the conduction band edge and .DELTA.Ev is the discontinuity between the barrier layer and a quantum well layer in the valence band edge. By this construction, the absorption peak when no electric field is applied significantly shifts toward the longer wavelength side, resulting in a large difference between the absorption peak wavelength when no electric field is applied and the absorption peak wavelength when an electric field is applied, whereby the absorption loss of a semiconductor optical modulator when no electric field is applied is reduced.

Abstract: A semiconductor laser device has an active layer, a cladding layer, and a contact layer successively disposed on a semiconductor substrate. A pair of electrodes for passing a current parallel to the cladding and contact layers and perpendicular to the resonator direction of the active layer for heating the active layer are disposed opposite the stripe-shaped active layer. The pair of electrodes are disposed on the contact layer and the contact layer between the pair of electrodes is missing. One of the pair of electrodes may be disposed directly on the cladding layer. An improved wavelength change response property as a function of the active layer temperature controlling current flowing between the two electrodes is obtained. Further, the production of the laser is easy.