Abstract: Optical fiber-based wireless systems and related components and methods are disclosed. The systems support radio frequency (RF) communications with clients over optical fiber, including Radio-over-Fiber (RoF) communications. The systems may be provided as part of an indoor distributed antenna system (IDAS) to provide wireless communication services to clients inside a building or other facility. The communications can be distributed between a head end unit (HEU) that receives carrier signals from one or more service or carrier providers and converts the signals to RoF signals for distribution over optical fibers to end points, which may be remote antenna units (RAUs). In one embodiment, calibration of communication downlinks and communication uplinks is performed to compensate for signal strength losses in the system.

Abstract: Methods and systems for normalized least mean square phase estimation are shown that include receiving optical transmissions that include a modulated signal, determining a step size based on a signal-to-noise ratio (SNR) and a laser linewidth that provides a balance between convergence speed and precision, estimating phase error using the determined step size, derotating the modulated signal to remove the estimated phase error, and demodulating the derotated signal to produce a bitstream.

Abstract: [Problem] This invention aims at solving the problem of how a subscriber premises-side optical network unit can be switched to an evaluation mode without the use of a jig board. [Means for Solving the Problem] The invention refers to a subscriber premises-side optical network unit (ONU 10) which is connected to a center-side optical network unit (OLT 1a) via an optical transmission line (optical fiber 2, 4) and to an external device (switch 6) via an electric signal line (electric signal line 5); comprising a memory (memory switch 15a) the stored content of which can be directly or indirectly rewritten by the external device; a detection part (CPU 15) for detecting that the content of the memory has been rewritten; and a control part (CPU 15) for performing, when the detection part detects that the stored content of the memory has been rewritten, a control whereby the optical sending part which sends optical signals to the optical transmission line is put into a continuous light emission state.

Abstract: A method and system of data transmission; the method comprising: converting data into qubits; transmitting a first qubit; measuring the first qubit at receiver location; determining whether or not to transmit portions of data from a sequential successive qubit based upon the value of the first qubit measured at the receiver location.

Abstract: The present invention is an optical system configured for enabling co-transmission (ex.—co-propagation) of a reference signal and a carrier signal (ex.—or a phase encoded signal and a reference signal) in a same fiber. Since it is configured for enabling said co-transmission, the optical system of the present invention promotes reduced transmission microphonic sensitivity in the optical system.

Abstract: The present invention is a differential M phase shift keying optical receiving circuit to improve an identification property of a signal from an optical front-end unit having a plurality of lines. For this, the differential M phase shift keying optical receiving circuit includes: a light-electricity converter for outputting a plurality of electronic signals in which phase-modulated element is intensity modulated from a received optical signal; a data reproduction unit for reproducing a plurality of data signals synchronized with a common clock signal from the plurality of electronic signals output from the light-electricity converter; a clock signal generation unit for generating the common clock signal to be used for reproducing the plurality of data signals in the data reproduction unit with the use of one of the plurality of electronic signals output from the light-electricity converter; and a selection unit for selecting an electronic signal to be used for generating the common clock signal.

Abstract: A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments.

Abstract: A scan acquisition technique for acquiring terminals (62, 64) that does not rely on precise alignment between a sensor (66, 70) and a transmitter (68, 72) associated with the terminals (62, 64). The terminals (62, 64) separate uncertainty regions (76, 78) into a plurality of sections (88, 90). Scan beams (82, 84) include encoded information of what section (88, 90) the scan beam (82, 84) is currently scanning. Each terminal (62, 64) will eventually receive the scan beam (82, 84) of the other terminal (62, 64). When it does, it will encode its scan beam (82, 84) with both the outgoing code and the return code for that section (88, 90), so that when it's scan beam (82, 84) is received by the other terminal (62, 64), that terminal (62, 64) will know what scan section (88, 90) the other terminal (62, 64) is located.

Abstract: The present invention relates to an optical receiver, in which the transmittance of a Mach-Zehnder interferometer can be locked at a normal operation point in a simple structure and control. A transmittance detecting circuit and a minute modulation signal detecting circuit are provided in parallel after a balanced optical receiver, and a switch is selectively connectable either a minute modulation signal detecting circuit and a transmittance detecting circuit. In the initial stage of frequency pull-in, the switch is set to connect the transmittance detecting circuit to the synchronous detection circuit. If the transmittance detecting circuit detects that the transmittance of the Mach-Zehnder interferometer at the carrier frequency becomes a desired transmittance, the connection of the switch is switched from the transmittance detecting circuit to the minute modulation signal detecting circuit.

Abstract: OCDMA systems provide for storage and retrieval of OCDMA data while maintaining OCDMA encoding. One system includes an optical splitter that receives an OCDMA data stream having a multiple wavelengths of light. A plurality of tunable light filters is optically interconnected with the optical splitter. A controller tunes the tunable light filters such that they switch wavelengths of the OCDMA data stream over time. A plurality of light detectors is respectively coupled to the tunable light filters to convert the filtered optical data streams from the tunable light filters to electronic data streams. Each generated electronic data stream is stored with a corresponding storage volume. Retrieval of the OCDMA data is performed by reversing the wavelength switching used to store the OCDMA data stream. The electronic data streams are thereby converted to optical data streams using tunable light generators and subsequently converted into the OCDMA data stream with an optical coupler.

Abstract: In accordance with the teachings of the present invention, a system and method for managing different transmission architectures in a passive optical network (PON) is provided. In a particular embodiment, a method for managing different transmission architectures in a PON includes transmitting traffic in an upstream or downstream direction in a first time-slot in a PON at each channel of a first set of one or more channels. The method also includes transmitting traffic in the same upstream or downstream direction in a second time-slot in the PON at each channel of a second set of one or more channels that provide greater bandwidth than the first set of one or more channels, wherein at least one channel of the first set at least partially overlaps at least one channel of the second set but is not identical to the at least one channel of the second set.

Abstract: The present invention provides a method for determining the bandwidths of optical fibers, wherein the method provides the coupling of light with a first optical power and a first modulation frequency into an optical fiber, as well as measuring a first signal level as a function of the optical power of the light of the first modulation frequency, coupling light with the second optical power and a second modulation frequency into the optical fiber, measuring a second signal level as a function of the optical power of the light of the second modulation frequency, and determining the bandwidths of the optical fibers as a function of the first and second coupled optical [power and/or] the measured first and second signal levels while using a predetermined specification that describes the frequency-dependent attenuation response of the optical fiber, wherein the first and the second modulation frequencies have essentially the same value.

Abstract: In one embodiment, a down conversion receiver is provided for a phase modulated optical signal. This may include an optical coupler coupled to be capable of receiving a phase modulated signal and a local oscillator signal, and a modulator coupled to an input of the optical coupler so as to be capable of modulating one of: (1) a phase modulated signal; or (2) a local oscillator signal. A photodetector circuit is located to be capable of detecting signals coupled by the optical coupler, with a sub-band selector circuit coupled to be capable of receiving signals from the photodetector circuit. The sub-band selector circuit has an output coupled to a modulating input of the modulator.

Abstract: The invention relates to a method for detecting a check-back signal in a transmission system for optical signals. According to said method, a constant proportion of the output in a defined frequency range of the check-back signal is concentrated in a narrow-band spectral range and is determined after a transmission phase by means of a narrow-band detection of the concentrated energy around the spectral range. If no signal is identified during the narrow-band detection, a line interruption is determined and no pump source is switched on for safety reasons. The narrow-band detection of the check-back signal also allows the transmission attenuation of the transmission system to be measured.

Abstract: Free space optical communication systems, methods, and apparatuses are provided. A system embodiment includes a photodetector for receiving a beacon signal transmitted from a ground communication apparatus, a light source for emitting a light beam toward a source of the beacon signal, where the light beam includes a signal to be transmitted, and a high speed tracking actuator coupled to the light source for moving the light source to maintain the light beam in a direction toward the source of the beacon signal transmitted from the ground communication apparatus.

Abstract: A WDM fiber optic communication system is operative to transmit WDM signals between multiple nodes. Each node has a booster EDFA, and in-band and out-of-band supervisory channels monitoring the integrity of a link by generating and detecting respective in-band and out-of-band control signals. The booster EDFA receives the multiplexed WDM and IB signals and generates an output signal carried by fibers between the nodes. The booster EDFA switches from an automatic gain control regime upon detecting of at least one of the IB and OB control signals to an automatic power control regime upon loss of both IB and OB control signals. The output signal of the EDFA in the AGC regime has a high power sufficient for transmitting the WDM and IB signals, and has a low power in the APC regime sufficient for transmitting only the IB control signal.

Abstract: A peaking current generating section generates a spire-shaped peaking current that is in synchronism with the transitions of the digital signal, at the rising edge and the falling edge. A light emitting element driving section produces a driving current obtained by combining together a signal amplitude current according to the amplitude of the digital signal and the peaking current. Then, the light emitting element driving section drives a light emitting element by using the driving current. A signal analysis section analyzes the digital signal so as to set a control signal based on the pulse width of the digital signal. A clipping section clips the peaking current of the driving current according to the control signal set by the signal analysis section.

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

Abstract: Embodiments of optical network evaluation systems and methods are disclosed. One system embodiment, among others, comprises a processor configured with logic to provide a cross layer model of disturbance propagation in an optical network based on a combination of a physical layer model and a network layer model, the physical layer mode based on the disturbance propagation having a threshold effect only on nodes along a route followed by the disturbance.

Abstract: A link connectivity verification message to recognize a physical link connection state is transmitted from the WDM to the PXC on a C-plane. The PXC transmits a link connectivity verification ACK message including information representing a physical link connection state, and the WDM transmits a cross-connect instruction message to cross-connect a transmission side and a reception side of a port (port 1) of the PXC. Probe light transmitted from the port (port a) of the WDM is turned back by a cross-connect of the port (port 1) of the PXC. The WDM receives the probe light to verify a link connectivity.