Abstract: An optical driving device and an optical communication system are provided which can improve signal quality of laser light that uses a PAM method. A laser driver drives a semiconductor laser by using an N-level (N is an integer of 3 or more) PAM signal. A clock control circuit determines a driving timing of the laser driver. In a case where N=4, for example, the clock control circuit determines a driving timing in association with a transition of the PAM signal from a fourth level to a first level to be earlier than a driving timing in association with a transition in an opposite direction by a first time, assuming that levels are the first level, . . . , and the fourth level in an order from a level at which light intensity is minimum.

Abstract: An optical driving device and an optical communication system are provided which can improve signal quality of laser light that uses a PAM method. A laser driver drives a semiconductor laser by using an N-level (N is an integer of 3 or more) PAM signal. A clock control circuit determines a driving timing of the laser driver. In a case where N=4, for example, the clock control circuit determines a driving timing in association with a transition of the PAM signal from a fourth level to a first level to be earlier than a driving timing in association with a transition in an opposite direction by a first time, assuming that levels are the first level, . . . , and the fourth level in an order from a level at which light intensity is minimum.

Abstract: A second optical modulator is provided between a semiconductor laser and a first optical modulator. Further, a second optical waveguide branched from a first optical waveguide is provided between the semiconductor laser and the second optical modulator, and a light receiving element which converts received laser light into a second electrical signal is provided at an end of the second optical waveguide. Furthermore, the second optical modulator adjusts a light intensity of the laser light entering the first optical modulator to a fixed light intensity, based on data transmitted as the second electrical signal. Still further, the first optical modulator modulates the laser light based on data transmitted as a first electrical signal, and converts the first electrical signal into an optical signal.

Abstract: A photoelectric conversion device is provided that has high linearity of output current to illuminance and is applicable to illumination sensors. The photoelectric conversion device outputs appropriate current by complementing first current, which is generated in response to incident light, with complementary current. The complementary current is generated based on second current flowing in response to the light. The second current is generated by a device having the same element area as that of a device that generates the first current. When the second current flows, the complementary current is generated based on a direction of the second current and is then added to the first current.

Abstract: Provided is an optical disk device to output a reproduction signal to reproduce an optical disk, including: a light output circuit to output light having a high frequency superimposed thereon; a first light receiving circuit to receive the light to output a first voltage corresponding to an amount of the light; a second light receiving circuit to output a second voltage corresponding to an amount of reflected light from the optical disk; an arithmetic circuit to output a calculation result based on a difference between the first voltage and the second voltage; and a reproduction signal generating circuit to control one of the first voltage and the second voltage based on the calculation result to generate the reproduction signal to reproduce the optical disk.

Abstract: A semiconductor light receiving element has: a semiconductor substrate; a plurality of photodiodes formed on the semiconductor substrate and configured to receive respective lights of different wavelengths; and an anti-reflection film provided on light receiving surfaces of the plurality of photodiodes. A structure of the anti-reflection film on at least one photodiode of the plurality of photodiodes is different from a structure of the anti-reflection film on another photodiode of the plurality of photodiodes.

Abstract: A semiconductor light receiving element has: a semiconductor substrate; a plurality of photodiodes formed on the semiconductor substrate and configured to receive respective lights of different wavelengths; and an anti-reflection film provided on light receiving surfaces of the plurality of photodiodes. A structure of the anti-reflection film on at least one photodiode of the plurality of photodiodes is different from a structure of the anti-reflection film on another photodiode of the plurality of photodiodes.

Abstract: The present invention discloses a semiconductor laser device having: a lead frame; a resin molding provided for sealing a part of said lead frame and including a main body and a flange portion having opposite end faces, said resin molding being formed into such a shape that said flange portion protrudes outwardly from a periphery of said main body; a laser chip having an optical axis and mounted on a surface of said lead frame for emitting laser light; and a heat-radiating fin provided on said lead frame for cooling said laser chip, said heat-radiating fin being disposed in an exposed state on the side of at least one of said two end faces of said flange portion.

Abstract: In an image forming apparatus, a mechanism for scanning the inner periphery of a hollow cylindrical drum has stationary optics including two semiconductor lasers fixed in place. The two lasers have their p-n junction planes positioned perpendicular to each other, i.e., one of them is horizontal while the other is vertical. Lights from the lasers are combined on the same axis by a polarizing beam splitter. A quarter-wave plate has its optical axis inclined .+-.45 degrees relative to the direction of polarization. The combined wave from the beam splitter is transformed by the quarter-wave plate to light having a clockwise and a counterclockwise polarization overlapping each other on the same axis. In the rotary optics, another quarter-wave plate converts the incident light to a composite wave of linear polarizations perpendicular to each other. This composite wave is incident to a splitting element as a P wave and an S wave or as ordinary rays and extraordinary rays.