Abstract: There is provided a method in a wavelength convertible flexible optical wavelength-division multiplexing (WC-FWDM) network. The network has a plurality of optical nodes interconnected by a plurality of optical fibers. The network is for providing an overall spectrum divisible into a set of consecutive wavelength slots. At least one optical node has at least one wavelength converter for wavelength conversion. The method includes determining a channel route through the network commencing at a source node and ceasing at a destination node. The determined channel route is selectively tunable responsive to selected ones of a plurality of routing methods. The routing methods are so selected responsive to a routing policy having one or more objectives of minimization of channel blocking, minimization of a number of wavelength converters used in the network, and minimization of physical distance traversed by a channel, and minimization of operating wavelengths of a channel.

Abstract: A method of providing routes through heterogeneous subsystems in an optical network is disclosed, which includes generating, using a processing device, a reachability matrix based on subnetwork information; and generating, using the processing device, a topology associated with the optical network using the reachability matrix. The method also includes determining, using the processing device, a shortest path through the optical network using the reachability matrix and a cost model graph; and displaying, using a graphical user interface, subsystems associated with the shortest path, regeneration locations associated with the shortest path, wavelengths associated with the shortest path, the topology, and the shortest path. Corresponding apparatus and computer-readable storage media are also disclosed.

Abstract: Disclosed herein is an optical network terminal. The Optical Network Terminal (ONT) includes a laser diode for generating an optical signal to be transmitted to the OLT. A laser diode driving unit supplies driving current required for light emission of the laser diode. A driving current detection unit detects the driving current. A light emission time determination unit calculates a light emission time of the laser diode depending on a time for which the driving current is detected, and outputs a power control signal including information about results of a comparison between the light emission time of the laser diode and a preset reference time. A power supply voltage control unit interrupts a power supply voltage of the laser diode driving unit when the power control signal includes information indicating that the light emission time of the laser diode is longer than the reference time.

Abstract: Optical safety functions are incorporated into protection switching modules which maintain redundant pathways to avoid interruptions in optical network connections. The optical safety functions which lower optical power levels upon interruptions of optical connections are effectively combined with protection switching procedures which are also triggered by interruptions in optical network connections. The interoperation of protection and safety processes keep optical power levels below hazardous levels at system points which might be accessible to human operators.

Abstract: An optical switching device includes plural wavelength selective switches that respectively have a first port and a plurality of second ports; and an optical coupler that has a plurality of third ports on an input-side or an output-side, respectively optically coupled to the first ports of the wavelength selective switches.

Abstract: A communications device includes a transmitter device having first and second optical sources and generating respective first and second modulated optical carrier signals at first and second optical carrier frequencies based upon an input signal. The communications device also includes an optical waveguide coupled to the transmitter device, and a receiver device coupled to the optical waveguide and including an FM-PM discriminator having a transfer function with a positive slope portion and a negative slope portion so that the first optical carrier frequency is positioned on the positive slope portion and the second optical carrier frequency is positioned on the negative slope portion.

Abstract: Consistent with the present disclosure, an optical communication system, such as a passive optical network (PON), is provided that includes an optical line terminal (OLT) and a plurality of optical network units (ONUs). The OLT includes a plurality of photonic integrated circuits that have both optical transmitters and receivers provided therein. Accordingly, the OLT may have fewer components and a simpler, more reliable and cost-effective design than a conventional OLT including discrete components. In addition, various ONU configurations are provided that also have a simple design and fewer components. Thus, ONUs consistent with the present disclosure may also have reduced costs.

Abstract: A method for generating an optical single sideband signal comprising the steps of splitting an optical field into two parts and introducing a relative phase delay of +/??/4 radians in each direction of transmission to one of the parts, intensity reflection-modulating each part with electrical signals having a relative phase delay of +/??/2 radians and then recombining the reflection-modulated signals.

Abstract: A dispersion compensation design system includes a changing unit setting a changed value for the amount of dispersion compensation for a span connecting nodes constituting an optical network; a path classification unit determining whether respective paths in the optical network are capable of transmission with the changed value and classifying one or more of the paths as second category paths based on the determination results; an updating unit updating the amount of dispersion compensation with the changed value if the number of the second category paths in the latest classification result is less than the number of the second category paths in the retained previous classification result; and a repeating unit that, if not all of the paths in the optical network are capable of transmission, prevents use of combinations of amounts of dispersion compensation applied to the spans in the second category paths in the latest classification result.

Abstract: There is a need to prevent two receivers from converging on a state of receiving the same polarization state, fast start receivers, and ensure highly reliable operations. A polarization-multiplexed transmitter previously applies frequency shifts of frequencies +?f and ??f to X-polarization and Y-polarization digital information signals to be transmitted. Optical field modulators modulate and polarization-multiplex the signals. As a result, a frequency difference of 2?f is supplied to X-polarization and Y-polarization components. A polarization diversity coherent optical receiver 215 receives the signal. A frequency estimation portion in a digital signal processing circuit detects a frequency difference signal in both polarization components. This signal is used to a polarization splitting circuit in the digital signal processing circuit.

Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.

Abstract: Adaptive power setting techniques for optical transceivers are provided. Optical signals are received at a first optical transceiver device that are transmitted from a second optical transceiver device. A receive power of the optical signals received at the first optical transceiver device from the second optical transceiver device is determined. A characteristic of optical signals transmitted by the first optical transceiver device to the second optical transceiver device is modulated to indicate to the second optical transceiver device a disparity of the receive power with respect to a target receive power level at the first optical transceiver device. Conversely, the first optical transceiver device adjusts a power level of optical signals transmitted by the first optical transceiver device to the second optical transceiver device based on a characteristic of the optical signals received at the first optical transceiver device.

Abstract: There is provided an optical fiber communication system restricting enlargement of the diameter of an optical fiber as well as enabling achievement of a large-capacity optical communication with a small number of optical fibers. An optical fiber communication system 100 includes an optical transmitter 10 transmitting a plurality of optical signals in parallel, a multicore fiber 20 in which outer circumferences of a plurality of cores are covered with a common clad, and the respective optical signals transmitted in parallel from the optical transmitter 10 are input into the cores, and an optical receiver 30 receiving the optical signals output in parallel from the respective cores of the multicore fiber, wherein the optical transmitter 10 and the optical receiver 30 perform a MIMO communication.

Abstract: A digital coherent receiver includes a front end, an A/D convertor, and a processor. The front end converts a light signal into an electric signal by using a signal light and a local oscillator light. The A/D convertor converts the electric signal of the front end into a digital signal. The processor calculates a spectrum gravity center of the digital signal converted by the A/D convertor, estimates a frequency offset of the digital signal based on the calculated spectrum gravity center, and reduces the frequency offset of the digital signal based on the estimated frequency offset.

Abstract: A method of generating an information-bearing optical signal (614) from input digital information (602) includes generating (604, 606) an information-bearing electrical signal comprising an in-phase (I) component and a quadrature (Q) component. Each of the components has a predetermined baseband bandwidth requirement (B). The I and Q signal components are combined (610) with corresponding I and Q components of a radio frequency (RF) carrier (608). The carrier has a central frequency greater than the signal bandwidth requirement (B). An optical source is modulated (612) with the combined I and Q signal and carrier components, in order to produce a modulated optical signal (614) which comprises an optical carrier corresponding with the RF carrier, and substantially only a single information-bearing optical sideband in an optical frequency domain, corresponding with the information-bearing electrical signals. Transmitters implementing the method are also disclosed.

Abstract: A relay station has an optical switch that switches a reception path of an optical signal. The relay station generates a subsignal that has a wavelength different from the wavelength of a data signal corresponding to a signal to be transmitted and transmits an optical signal obtained by multiplexing the generated subsignal and the data signal. In this state, when the data signal is not included in the received optical signal, the relay station determines whether the subsignal is included in the optical signal. When it is determined that the subsignal is included, the relay station maintains a connection path of the optical switch without switching the connection path.

Abstract: The invention relates to the field of optical transmission systems. In particular, the invention relates to a system and a method for adjusting an optical OFDM transmission system in a power optimized manner. An optical OFDM transmitter (310) operating at an overall bit-rate is provided. It comprises an adjustable mapping unit (314) associated with one of N OFDM subcarriers, operable to map M bits of a digital input signal (360) into a constellation point, thereby yielding a subcarrier signal of the corresponding OFDM subcarrier. Furthermore, it comprises an adjustable transformation unit (315, 316), operable to transform the subcarrier signal to yield an electrical output signal. In addition, the OFDM transmitter comprises an electrical-to-optical converter (324, 325), operable to convert the electrical output signal into an optical output signal.

Abstract: A digital coherent receiver includes a front end, an A/D convertor, and a processor. The front end converts a light signal into an electric signal by using a signal light and a local oscillator light. The A/D convertor converts the electric signal of the front end into a digital signal. The processor calculates a spectrum gravity center of the digital signal converted by the A/D convertor, estimates a frequency offset of the digital signal based on the calculated spectrum gravity center, and reduces the frequency offset of the digital signal based on the estimated frequency offset.

Abstract: Consistent with the present disclosure, an optical communication system, such as a passive optical network (PON), is provided that includes an optical line terminal (OLT) and a plurality of optical network units (ONUs). The OLT includes a plurality of photonic integrated circuits that have both optical transmitters and receivers provided therein. Accordingly, the OLT may have fewer components and a simpler, more reliable and cost-effective design than a conventional OLT including discrete components. In addition, various ONU configurations are provided that also have a simple design and fewer components. Thus, ONUs consistent with the present disclosure may also have reduced costs.

Abstract: An apparatus for simulating radio frequency (RF) signal propagation characteristics in a wireless communication network is disclosed. The apparatus includes a first RF terminal and a second RF terminal. A first optical modulator is in electrical communication with the first RF terminal. An optical delay line is in optical communication with the first optical modulator. A first optical demodulator is in optical communication with the optical delay line and in electrical communication with the first RF terminal. A second optical demodulator is in optical communication with the optical delay line and in electrical communication with the second RF terminal. A second optical modulator is in electrical communication with the second RF terminal and in optical communication with the optical delay line.