Abstract: The present invention provides an optical receiving device, in which a portion of an optical signal is deflected for optical axis detection only when the optical axis is misaligned to thereby achieve a high S/N ratio of a received signal. A condensing section 100 condenses a received optical signal. An optical element 110 includes a transmission region 111 and a deflecting region 112, and receives the optical signal, which has been condensed through the condensing section 100. A signal light receiving section 120 receives the transmitted light, which has been transmitted through the transmission region 111. A detection light receiving section 130 receives deflected light, which has been deflected through the deflecting region 112 and performs a photoelectric conversion on the received light to thereby output a detection intensity signal that indicates an intensity of the deflected light.

Abstract: A transmission device includes a first light emission unit having a light source for emitting one optical signal. A reception unit includes an X-Y address system image sensor, having a pixel region including a plurality of pixels, for receiving the optical signal by the pixel region; a classification unit for creating classification information representing a pixel group including pixels, among the plurality of pixels, which are irradiated with the optical signal; and a control unit for controlling the X-Y address system image sensor in accordance with the classification information to simultaneously read signals of the pixels belonging to the pixel group.

Abstract: In order to improve a transmission speed of multilevel light transmission, increasing the number of light emitting elements is effective. However, in a method in which light outputs from a plurality of light emitting elements are added, because common mode noise contained in the light outputs is added, deterioration in transmission quality caused by the common mode noise prominently arises. Therefore, a difference between two light outputs is previously assigned to data to be transmitted. Specifically, an optical transmitter 102 converts data Dt to multilevel optical signals OSm1 and OSm2 and transmits the converted multilevel optical signals to an optical receiver 103. The optical receiver 103 restores the data Dt which is previously assigned to a difference between electrical signals ESr1 and ESr2 converted from the multilevel optical signals OSm1 and OSm2.

Abstract: A CATV station apparatus subjects received optical signals to processes such as optical-electrical conversion, signal separation, coupling, and demodulation for obtaining an uplink signal. A received photocurrent monitoring section compares a received photocurrent at a optical receiving section with a predetermined reference current. If the received photocurrent is equal to or higher than the reference current, an amplifying section amplifies a signal output from a signal separating section at a predetermined level. If the received photocurrent is lower than the reference current, on the other hand, it is determined that a non-linear phenomenon, such as stimulated Brillouin scattering, has occurred in an optical fiber. The amplifying section then outputs a signal at a level which does not affect, even after being coupled with other signals, communications performed by other optical transmission systems.

Abstract: A space optical transmission apparatus is provided which achieves high-speed simultaneous space optical transmission with respect to a plurality of terminals. In the space optical transmission apparatus, a light receiving section receives an optical signal from a terminal. A control section estimates how much optical axes of a master station and the terminal are deviated from each other, based on the received optical signal. The control section selects one of a plurality of light sources which requires a smallest amount of shift of an optical axis thereof, based on the estimated optical axis deviation amount, so as to communicate with the terminal.

Abstract: There are provided a first modulation section for performing low-speed digital modulation of first data; a second modulation section for performing high-speed digital modulation of second data; a first light transmitting section for emitting/quenching visible light in accordance with an output signal of the first modulation section to transmit a visible light signal which conveys the first data; and a second light transmitting section for changing the intensity of the infrared light in accordance with an output signal of the second modulation section to transmit an infrared light signal, which conveys the second data, in parallel with the visible light signal.

Abstract: Modulators respectively modulate baseband signals into IF signals having different frequencies. A multiplexer multiplexes the IF signals. An electrical-optical converter intensity modulates the multiplexed IF signals into optical signals. A local oscillation signal source outputs a predetermined local oscillation signal. An external modulator intensity-modulates the optical signal using the local oscillation signal. An optical branching portion branches the intensity-modulated optical signal and respectively outputs branched optical signals to radio base stations. An optical-electrical converter converts the optical signal into an electric signal, to obtain an RF signal by frequency-converting the IF signal. An antenna only transmits a component having a desired radio frequency extracted in a band filter from the RF signal to a subscriber terminal.

Abstract: A light emission section, including a light emitting element such as a semiconductor laser, emits a light beam in accordance with communication data. A light reception section, including a light receiving element such as a photodiode, receives the light beam emitted by the light emission section. The light emission section and the light reception section are positioned and an emission angle and an incidence angle of the light beam are determined such that the light beam emitted by the light emission section to the light reception section is prevented from being reflected by a surface of the optical reception section and/or a mounting substrate and being returned to the light emission section.

Abstract: There included are a plurality of light receiving sections (121, 122) for receiving a plurality of optical signals (R1, R2) and respectively converting the received optical signals to a plurality of electrical signals (r1, r2); a first calculating section (130) for subjecting the plurality of electrical signals (r1, r2) to a process of canceling interference components occurring due to propagation of the plurality of optical signals through space; and a second calculating section (140) for calculating, with respect to each of the plurality of electrical signals whose interference components have been canceled by the first calculating section, whether or not a distortion occurring due to optical beat interference has a value less than or equal to a predetermined permissible value.

Abstract: A light receiver comprises a Fresnel lens for collecting light signals, and a light receiving element disposed closer to the Fresnel lens than the focal point of the Fresnel lens for receiving the light signals collected by the Fresnel lens. The Fresnel lens comprises a lens surface group having a plurality of lens surfaces, and a back cut surface group having a plurality of back cut surfaces connecting the lens surfaces. The back cut surfaces are inclined with respect to the center axis of the Fresnel lens. Thus, the light receiver has a high light collection efficiency of light signals incident within a certain acceptance angle.

Abstract: A wireless communication system capable of keeping a level of a wireless signal received by a relay apparatus within a predetermined dynamic range. In a control apparatus, a transmitting section converts a downstream electric signal into a downstream optical signal and transmits the downstream optical signal to the relay apparatus via an optical transmission path. The relay apparatus converts the received downstream optical signal into a downstream electric signal and transmits the downstream electric signal as a wireless signal to a wireless communication terminal from a transmitting/receiving antenna section. In the relay apparatus, a level adjustment section adjusts the level of the wireless signal transmitted by the relay apparatus such that the receiving level of the wireless signal received by the relay apparatus is kept within a predetermined range.

Abstract: An optical space transmission module is provided, which reduces an upper limit of light output based on safety standard of laser, reduces light returned to a laser, and is made smaller in size. The optical space transmission module comprises a light emitting section 100 which outputs a transmission light, a base section including a reflection section 111 which reflects the transmission light, a reflection type diffusion section 120 which reflects and converts into a diffused light the reflected light which has been reflected by the reflection section 111. The reflection section 111 has a function to increase a beam diameter of the transmission light after reflection.

Abstract: Modulators respectively modulate baseband signals into IF signals having different frequencies. A multiplexer multiplexes the IF signals. An electrical-optical converter intensity modulates the multiplexed IF signals into optical signals. A local oscillation signal source outputs a predetermined local oscillation signal. An external modulator intensity-modulates the optical signal using the local oscillation signal. An optical branching portion branches the intensity-modulated optical signal and respectively outputs branched optical signals to radio base stations. An optical-electrical converter converts the optical signal into an electric signal, to obtain an RF signal by frequency-converting the IF signal. An antenna only transmits a component having a desired radio frequency extracted in a band filter from the RF signal to a subscriber terminal.

Abstract: An optical transmitter for performing high-rate data communication by means of optical space transmission is provided, which can reliably perform optical axis adjustment manually and visually, and can prevent a device from being made large in size and manufacturing cost of the device from being increased by using an simply-constructed optical transmitter. Thus, the optical transmitter of the present invention comprises an incident beam restriction section operable to allow only a visible beam which is emitted by a terminal located within a range in which an infrared beam is emitted and incident thereon to pass therethrough, a reflection section operable to reflect the visible beam which has passed through the incident beam restriction section, and a light source operable to emit the infrared beam to pass through the reflection section according to a data transmission request signal from the terminal.

Abstract: A plurality of first refraction surfaces 121 and a plurality of second refraction surfaces 122 are alternately provided on an emission surface of a lens element 120 so as to form concentric circles each having an optical axis 113 at the center thereof, and having diameters different from each other, and a light reflected by a plurality of reflection surfaces 123 provided on an incident surface of the lens element so as to form concentric circuits each having the optical axis 113 at the center thereof and having diameters different from each other, is refracted and emitted by the plurality of second refraction surfaces 122 at desired angles. Therefore, it is possible to enhance efficiency and an emission intensity, and reduce variations in brightness of an emitted light without increasing the diameter of the lens element 120, thereby realizing a light emitting module 100 enabling advantageous performance.

Abstract: Modulators respectively modulate baseband signals into IF signals having different frequencies. Multiplexers multiplex the IF signals. A local oscillation signal source outputs a predetermined local oscillation signal. An external modulator intensity-modulates an optical signal using the local oscillation signal. An optical branching portion branches the intensity-modulated optical signal. Modulators respectively modulate the multiplexed IF signals onto the branched optical signals and then output the optical signals to radio base stations. Optical-electrical converters convert the optical signals into electric signals and antennas transmit the electrical signals to subscriber terminals.

Abstract: The present invention provides an optical receiving device, in which a portion of an optical signal is deflected for optical axis detection only when the optical axis is misaligned to thereby achieve a high S/N ratio of a received signal. A condensing section 100 condenses a received optical signal. An optical element 110 includes a transmission region 111 and a deflecting region 112, and receives the optical signal, which has been condensed through the condensing section 100. A signal light receiving section 120 receives the transmitted light, which has been transmitted through the transmission region 111. A detection light receiving section 130 receives deflected light, which has been deflected through the deflecting region 112 and performs a photoelectric conversion on the received light to thereby output a detection intensity signal that indicates an intensity of the deflected light.

Abstract: A light emission section 13, including a light emitting element such as a semiconductor laser, emits a light beam in accordance with communication data. A light reception section 23, including a light receiving element such as a photodiode, receives the light beam emitted by the light emission section 13. According to the present invention, the light emission section 13 and the light reception section 23 are positioned and an emission angle and an incidence angle of the light beam are determined such that the light beam emitted by the light emission section 13 to the light reception section 23 is prevented from being reflected by a surface of the optical reception section 21 and/or a mounting substrate 22 and being returned to the light emission section 13.

Abstract: An optical transmission apparatus is provided in which high optical output power is secured in an optical transmitter, the fine adjustment of the optical axis is unnecessary, and the propagation range of the optical output signal can be adaptively changed. A diffusing liquid lens includes a first liquid and a second liquid containing a scattering material that scatters light, and the curvature of the boundary surface between the first and the second liquids is changed according to the control voltage applied from a controlling unit. A first optical signal outputted from a light emitting device is diffused in the first liquid, and emitted as a second optical signal having a spread angle corresponding to the curvature of the boundary surface and a substantially uniform radiant intensity distribution.

Abstract: A first peaking current generating section 1 generates a first peaking current P1 in synchronism with the transitions of a digital signal S, being positive at the rising edge and negative at the falling edge. A second peaking current generating section 3 generates a second peaking current P2 in synchronism with the transitions of the digital signal S, being negative at the rising edge and positive at the falling edge. A first light emitting element driving section 2 produces a first driving current D1 obtained by combining together a signal amplitude current according to the amplitude of the digital signal S and a first peaking current P1. A second light emitting element driving section 4 produces a second driving current D2 obtained by combining together the signal amplitude current according to the amplitude of the digital signal S and a second peaking current P2.