Abstract: A quantum key delivery system includes an optical circulator, an optical low-pass filter, optical splitters, and first and second optical couplers arranged for outputting various wavelength components including correlated-photon pair wavelength components outputted from an optical loop path. The first and second optical couplers output light beams, which are sent over first and second quantum channels to first and second recipients, respectively. Other optical splitters are adapted to output light rays, from which first and second control signals are produced. From auxiliary idler light components transmitted over the first and second quantum channels, clock signals are extracted. The system thus extracts a clock signal for detecting arrival of photons, and stably operates with an expected value of the number of generated correlated photon pairs maintained at a substantially constant value.

Abstract: Methods and devices for detecting at least one first input signal superimposed on at least one second signal. The method comprises the steps of providing said at least one first input signal superimposed on at least one second signal to at least one half-wave rectifier; transforming, in said at least one half-wave rectifier, said at least one first input signal superimposed on at least one second signal into a half-wave rectified signal; providing said half-wave rectified signal to an envelope detector; and transforming, in said envelope detector, said half-wave rectified signal into an envelope signal and wherein the at least one half-wave rectifier comprises at least one optoelectronic device. In this way, a simpler and cheaper method and/or device are provided for e.g. detecting a transmitted information signal superimposed on a high frequency carrier signal.

Abstract: The present invention relates to an optical access system for dual service network, which mainly comprises an optical modulation device which is used to receive on-off keying (OOK) signal from cable network and radio frequency (RF) signal from wireless network, the optical modulation device then modulates the OOK signal and the RF signal to an optical signal and send out an output optical signal. Lastly, the output optical signal is being delivered to an optical receiving device through an optical fiber transmission channel, and the optical receiving device can access the OOK signal and RF signal from the output optical signal. In addition, the present invention does not require remote nodes (receiver side) to use any optical filter to discern on-off keying signal from cable network and RF signal from wireless network. The present invention can also apply to the field of wavelength-division multiplexing system.

Abstract: A bandwidth allocation and management system for cellular communication networks. The system includes at least one master optical switch and processing station, a number of aggregation base stations that are in optical fiber communication with a master optical switching and processing station and a number of auxiliary cellular base stations surrounded by and supported by each aggregation base station. In preferred embodiments a plurality of sets of three neighboring base stations are each adapted to receive and process RF signals transmitted by cellular users within a broadcast and receive range and transmit the RF signals received, by each of the three neighborhood base stations, from each of the cellular users in analog form to the master optical switching and processing station.

Abstract: Jitter reduction of electrical signals from limiting optical modules is described. In one example, a process includes receiving an amplitude limited electrical signal that has been converted from an optical signal, applying a filter to the received electrical signal, measuring an indication of jitter of the filtered signal, and selecting parameters of the linear filter based on the measured indication.

Abstract: Example embodiments may include a coaxial Free Space Optical (FSO) telescope providing a simplified and more precise structure. Example embodiment telescopes include a prism structure having at least two parallel surfaces associated with a filter and mirror. The filter may reflect or transmit optical signals based on their electromagnetic characteristics. Example embodiment systems include example embodiment coaxial FSO telescopes and transmitters and receivers for receiving and transmitting optical signals. A V-groove and/or lens array may be included in example embodiment FSO systems.

Abstract: An optical transmission device includes a wavelength multiplexing/demultiplexing unit, a plurality of transponders, an optical switch unit and a controller. The controller includes a table in which a plurality of items at least including priority order, a transmission label, a receiving label and a receiving label expected value correspond to the respective transponders. And the controller rewrites the transmission label of the transponder corresponding to the client device of the lower priority order than the priority order of the client device connected to the transponder of the irregular input, upon the optical signal provided by the wavelength multiplexing/demultiplexing unit to one of the transponders being irregular, and controls the label-changed transponder for which the transmission label has been rewritten so that the label-changed transponder provides the wavelength multiplexing/demultiplexing unit with the optical signal including the rewritten transmission label.

Abstract: A data transmission method for transmitting a digital optical signal over an optical transmission link includes creating a digital optical signal defining at least two service levels, each service level transporting information via a modulation scheme comprising at least three different modulation symbols. The data transmission method also includes transmitting the digital optical signal over the transmission link and receiving the transmitted digital optical signal at a remote end of the transmission link by demodulating the received signal and extracting the information of the at least two service levels. In case that the transmission performance is below a given threshold due to increased constraints of the transmission link a compensating action is taken to drop at least one of the service levels from the optical signal or to determine parameters associated with the transmission so as to increase one of the service levels to a predetermined quality level.

Abstract: Provided is an optical access system, including: an optical line terminal, a plurality of optical network units and an optical switching unit. The optical line terminal sends to the optical switching unit a control frame including a switching time when the optical switching unit is to make a switch from one of the optical communication paths between the optical line terminal and the plurality of optical network units to another, and an identifier of an optical communication path to which the switch is made in order to switch the optical communication paths between the optical line terminal and the plurality of optical network units. The optical switching unit switches the optical communication paths between the optical line terminal and the plurality of optical network units based on the switching time and the identifier of the optical communication path after switching which are included in the control frame.

Abstract: There is provided an optical transmission apparatus including: a plurality of wavelength selective switches including input ports, a transmission port, and monitor port used to output a light switched so that the light from the input port is monitored; a multiplexer to combine the lights output from the transmission ports of the plurality of wavelength selective switches; a monitor to monitor whether a same wavelength of the light output from the monitor port exists in wavelengths of the lights combined by the multiplexer; and a controller to control the wavelength selective switch so as to output, from the transmission port, the light switched to the monitor port in case that the same wavelength of the light output from the monitor port is absent in wavelengths of the lights combined by the multiplexer, based on a monitor result by the monitor.

Abstract: A lock-in ratio measurement system including a plurality of channels. Each of the channels generates and transmits a radiation signal modulated by a sequence of tones. The sequence of tones for each channel being unique in time to that respective channel. Each respective modulated signal is absorbed/reflected from a target or medium and received. Each channel computes a lock-in value based on the received modulation signal. The lock-in values are used to compute ratios between the channels for characterizing a target or medium.

Abstract: The light transmitting and receiving module includes a light outputting section; alight receiver which receives input light and which outputs an electric signal having an intensity corresponding to a light intensity of the input light; a first variably attenuation controller which variably attenuates the light output from the light outputting section; a second variably attenuation controller which variably attenuates the input light to the light receiver; a first switch which selectively switches a path through which the light from the first variably attenuation controller is output between a light transmitting path and an alternative path different from the light transmitting path; and a second switch which selectively switches light to be output to the second variably attenuation controller between light from an external entity and the light through the alternative path of the first switch.

Abstract: A method for enabling bidirectional data communication using a single optical carrier and a single laser source with the aid of an integrated, colorless demodulator and detector for frequency modulated signals, and a reflective modulator. A receiving optical system holds a technique for demodulation and detection of optical frequency modulated signals, enabling remodulation of the incoming signal to establish bidirectional communication with the transmitting optical system, without introducing a high penalty. A colorless demodulator and detector, which provides the functionality of a periodic filtering device for demodulation of the downstream, and also detection capability. The principle of operation of the CDD relies on the introduction of a comb transfer function with the help of a Semiconductor Optical Amplifier, by providing a reflected feedback signal to the CDD's active element.

Abstract: In a digital signal processing optical transmission apparatus such as a predistortion or OFDM type one, optical transmission at a stable S/N ratio is intended to be able to be made by controlling an output of an optical transmission signal with fixed average power, even if a peak to average power ratio of the optical transmission signal changes. The apparatus is provided with an average power calculation unit (30) that calculates the average power of a digital signal outputted from a digital signal processing circuit (2), and an optical power variable unit (31) that serves to make constant the average power of an optical transmission signal outputted from an optical vector modulator (5).

Abstract: In the case in which an input voltage to a comparator COMP reaches (½)×Vcc from initial Vcc in accordance with lowering of the electric potential at a nodal point N1, an output level of the comparator COMP is inverted to make the output level LOW. In the case in which the output level of the comparator COMP is made LOW, a switch for amplifying part SW3 is connected, and an optical receiver circuit 1 makes the shift to a half start-up state. A signal detector circuit SD as well is started up by the connection of the switch for amplifying part SW3. In the case in which an amplifying part 2 is started up, the signal detector circuit SD judges whether a transmission signal is included in an output from the amplifying part 2. In the case in which the signal detector circuit SD shows that a transmission signal is not included, the resetting switch SW2 is connected to reset a capacitor C1.

Abstract: An optical sensor system comprises one or more optical sensor devices, a master device and an electrical bus connecting the sensor devices to the master device. The bus comprises a signal daisy chain for the transmission of synchronization events. The sensor devices are adapted to detect a synchronization event at a signal input terminal, to time an optical activity based on this synchronization event and to provide at a signal output terminal a synchronization event delayed by an offset time with respect to the detected synchronization event. A property of the synchronization events provided by the sensor devices is indicative of an output value of the respective sensor device, corresponding to a state of an optical section to which the sensor is sensitive.

Abstract: When a neighbor ONU receives a signal with light intensity high enough to secure communication between an OLT and a remote ONU, the light intensity may be excessively high to damage a receiver of the neighbor ONU. In order to avoid such a problem, each ONU is notified of a downstream signal transmission plan (downstream light intensity map) prior to transmission of a downstream signal. Each ONU receives the downstream light intensity map (light intensity transmission schedule of downstream signal) in advance. Thus, the neighbor ONU can block or attenuate an optical signal addressed to the remote ONU, and the remote ONU can determine normal operation even when the remote ONU cannot receive a signal addressed to the neighbor ONU. Thus, the remote ONU can be prevented from issuing a wrong error signal.

Abstract: A detector module for the reception of optical signals (SE) including a module housing having at least one electrical and at least one optical bushing, at least one electrical assembly connected to the electrical bushing, and at least one optical assembly connected to the optical bushing, the electrical and optical assemblies being arranged within the module housing, the optical and electrical assemblies being connected to one another via at least one optical interface, and the electrical assembly having at least one photodiode for converting the optical output signals of the optical assembly into electrical signals. The optical assembly has at least one collimator and on the output side transmits at least one beam comprising collimated electromagnetic rays running parallel to one another via a free-radiating connection as optical interface to the electrical assembly, and the electrical assembly receives the beam from the optical assembly via the free-radiating connection.

Abstract: While altering a plurality of wavelength setting parameters according to a control sequence, a local oscillation light having a wavelength controlled by those wavelength setting parameters is generated. Further, the received signal light and the generated local oscillation light are mixed, and if an electric signal is generated by photoelectric conversion from the resulting light, then the wavelength control of the local oscillation light is terminated.

Abstract: An optical interface device determines whether frequency deviation of a clock signal corresponding to an optical signal from a client side is abnormal based on a stuff amount when subjecting a data signal corresponding to an optical signal input from the client side to a stuffing process, inserts an alarm indication signal (AIS) indicating that the frequency deviation is abnormal into a predetermined region of a data signal when the deviation is determined to be abnormal, and outputs an optical signal generated corresponding to the data signal to a WDM line side so as to transfer the AIS to another component disposed downstream therefrom, so that locating a site where an abnormal state occurs is made easier.