Abstract: A modulator with polarization marking comprising two input ports for receiving two optical signals at one wavelength, and exhibiting essentially perpendicular optical polarization states, capable of phase-modulating those signals with data signals and of combining them with polarization, characterized in that it comprises a source of phase overmodulation for overmodulating the phase of one of said two optical signals, said phase overmodulation exhibiting a modulation frequency substantially lower than the modulation frequency of said data signals. A method and a coherent receiver are also disclosed.

Abstract: A filtered laser array assembly generally includes an array of laser emitters coupled between external modulators and an arrayed waveguide grating (AWG). Each of the laser emitters emits light across a plurality of wavelengths including, for example, channel wavelengths in an optical communication system. The AWG filters the emitted light from each of the laser emitters at different channel wavelengths associated with each of the laser emitters. Lasing cavities are formed between each of the laser emitters and a back reflector coupled to an output of the AWG such that laser output from the laser emitters is provided at the respective channel wavelengths of the reflected, filtered light. The external modulators enable high speed modulation of the laser output. The modulated laser output may then be optically multiplexed to produce an aggregate optical signal including multiple channel wavelengths.

Abstract: An active network monitoring system for detecting an abnormality at a position between a communication office and a client includes a first monitoring module disposed on the communication office, a second monitoring module disposed on the client and an optical splitter. The first monitoring module has a first processor and a first laser diode. The second monitoring module has a second processor and a second laser diode. The first processor sends a digital signal to the first laser diode. The first laser diode modulates the digital signal into an optical signal and sends the optical signal to the second monitoring module via the optical splitter. The second laser diode converts the optical signal back to the digital signal, and sends the digital signal to the second processor to generate an identification signal of the client. The identification signal is transmitted to the communication office via the second laser diode.

Abstract: Embodiments provide a methodology for designing a large-scale non-blocking OCS using a multi-stage folded CLOS switch architecture for use in datacenter networks and fiber-rich backbone network POPs. One aspect employs a folded CLOS architecture because of its ease of implementation, enabling the topology to scale arbitrarily with increasing number of stages. The fraction of ports allocated for internal switch wiring (overhead) also increases with the number of stages. Design decisions are made to carefully optimize the insertion loss per module, number of ports per module, number of stages and the total scale required. Other embodiments include folded CLOS switch architectures having at least two stages. In one example, power monitoring may be included only on the leaf switches.

Abstract: We describe and demonstrate a novel and simple scheme to generate flattened optical subcarriers using only phase modulators driven by single frequency fundamental sinusoidal sources. 160.8 Gb/s PM-QPSK experiment over a single subcarrier has been demonstrated.

Abstract: Methods and systems for a narrowband, non-linear optoelectronic receiver are disclosed and may include amplifying a received signal, limiting a bandwidth of the received signal, and restoring the signal utilizing a level restorer, which may include a non-return to zero (NRZ) level restorer comprising two parallel inverters, with one being a feedback path for the other. The inverters may be single-ended or differential. A photogenerated signal may be amplified in the receiver utilizing a transimpedance amplifier and programmable gain amplifiers (PGAs). A received electrical signal may be amplified via PGAs. The bandwidth of the received signal may be limited utilizing one or more of: a low pass filter, a bandpass filter, a high pass filter, a differentiator, or a series capacitance on the chip. The signal may be received from a photodiode integrated on the chip, where the photodiode may be AC coupled to an amplifier for the amplifying.

Abstract: A heterodyne optical signal detector and method performed thereby, the signal detector including an optical signal spectrum shaper operable to modify the shape of the frequency spectrum of a received optical signal, a laser local oscillator (LO), and polarization beam splitters (PBSs) to divide the signal and the LO into orthogonal components, waveguides in which intermediate frequency (IF) signals are formed, balanced photodetectors (BPDs) arranged to receive the IF signals and operable to convert the IF signals into electric signals, and analog to digital converters (ADCs) that digitize the electric signals.

Abstract: The present invention discloses a clock recovery circuit, an optical receiver, and a passive optical network device. In the clock recovery circuit provided by the embodiment of the present invention, a first signal indicating whether a data loss abnormality occurs in initial serial data is introduced at a side of a phase detector, and a phase adjustment control signal is output to a phase adjustor according to a state of the first signal; and the phase adjustor performs different types of phase adjustment according to a state of the initial serial data, so that a data sampler can recover an accurate clock when the initial serial data is normal and can implement smooth switching of output clock information in special cases such as initial serial data clock loss or recovery, and no great abrupt phase change occurs, thereby ensuring stable and reliable working of a system.

Abstract: A method for an adaptive forward error correction (FEC) in a passive optical network. The method comprises selecting an initial downstream FEC code to be applied on downstream data transmitted from an optical line terminal (OLT) to a plurality of optical network units (ONUs) of the PON; communicating the selected downstream FEC code to the plurality of ONUs; receiving at least one downstream bit error ratio (BER) value from at least one ONU of the plurality of ONUs, wherein the downstream BER value is measured respective to downstream data received at the at least one ONU; changing the selected downstream FEC code to a new downstream FEC code based on a plurality of downstream BER values measured by the at least one ONU; and communicating the new downstream FEC code to the plurality of ONUs.

Abstract: A detecting apparatus includes a threshold detection circuit that detects by a switchable time constant, a threshold of a level of an input optical burst signal; an input detection circuit that detects input of the optical burst signal; a level detection circuit that detects a level of the optical burst signal; a switching circuit that switches the time constant when a period that corresponds to the level detected by the level detection circuit has elapsed after the input is detected by the input detection circuit; and an output circuit that outputs the threshold detected by the threshold detection circuit.

Abstract: According to one embodiment, a transmission system includes a transmitter and a receiver. The transmitter includes a modulator configured to modulate transmission data at a chip rate to generate a modulation signal, and one or a plurality of light sources configured to emit visible light according to the modulation signal. The receiver includes a light receiver having one or more lines of light receiving elements to receive light in a first range including the visible light; and a demodulator configured to demodulate image data generated according to the light received by the light receiver to generate reception data corresponding to the transmission data. A following equation is satisfied ff<fm where fm is the chip rate, and ff is a frame rate of the light receiver.

Abstract: An optical transmitter includes an EA modulator, a photocurrent detection circuit, a modulator drive circuit, and a CPU. The EA modulator converts an input signal into an optical signal and outputs the optical signal. The photocurrent detection circuit detects an optical absorption current (a photocurrent) in the EA modulator. The modulator drive circuit controls the EA modulator. The CPU calculates a voltage to be applied to the modulator drive circuit based on the optical absorption current detected by the photocurrent detection circuit.

Abstract: The present disclosure relates to concatenated optical spectrum transmission systems and methods that allocate optical spectrum of groups of channels to reduce or eliminate deadbands or guardbands (i.e., unused optical spectrum) between channels. The concatenated optical spectrum transmission systems and methods include various techniques for using optical spectrum such as over the C-band or any other frequency bands. In particular, the concatenated optical spectrum transmission systems and methods provide a balance between fixed channel systems such as provided for by the International Telecommunication Union (ITU) and a more flexible system enabled by coherent optical detection. In an exemplary embodiment, the concatenated optical spectrum transmission systems and methods may utilize a Wavelength Selective Switch (WSS) and a plurality of moderate Common Mode Rejection Ratio (CMRR) coherent receivers in combination to achieve a concatenated optical spectrum.

Abstract: A system for delivering optical power over an optical conduit includes at least one optical power source delivering optical power to multiple outlet nodes in accordance with a multiple power access methodology.

Abstract: An optical transmitter may include a sample rate converter and a digital-to-analog converter operable to convert an inputted digital electrical signal to an analog optical signal. The signal converter may include a first interface operable to receive a digital electrical signal that may include a block of input data having N symbols in a time domain. The signal converter may also include: a first module operable to transform, via a Fourier Transform, the input data having N symbols from the time domain to a frequency domain; a second module operable to up-sample the N frequency domain samples so that there are 1.6N, 2N, or 2.67N frequency domain samples, for example; and then a third module operable to transform, via an inverse Fourier Transform, the 1.6N, 2N, or 2.67N frequency domain samples to an equivalent number of time domain samples at 1.6, 2.0, or 2.67 samples per symbol, respectively.

Abstract: An optical microphone includes: an acousto-optic medium section having a pair of principal surfaces and at least one lateral surface provided therebetween; a restraint section which is in contact with the at least one lateral surface for preventing a shape change of the acousto-optic medium section; and a light emitting section for emitting a light wave so as to propagate through the acousto-optic medium section between the pair of principal surfaces. The pair of principal surfaces are in contact with an environmental fluid through which an acoustic wave to be detected is propagating and are capable of freely vibrating, and an optical path length variation of a light wave propagating through the acousto-optic medium section, which is caused by the acoustic wave that comes into the acousto-optic medium section from at least one of the pair of principal surfaces and propagates through the acousto-optic medium section, is detected.

Abstract: A communications network element comprises an input to receive an input optical signal having an input spectral property and carrying input traffic, an output and a monitoring port. Optical signal processing apparatus to receive the input signal and to form an output optical signal having an output spectral property and carrying output traffic. An optical splitter to tap off a part of one of the input signal and the output signal to form a tapped signal having a respective one of the input spectral property and input traffic, and the output spectral property and output traffic. Optical signal transforming apparatus to receive the tapped signal and to apply an optical transfer function (OTF) to it to form an optical monitoring signal, and to provide the monitoring signal to the monitoring port. The OTF preserves the spectral property of the tapped signal and applies a time-domain obfuscation to the tapped signal.

Abstract: Disclosed herein is an apparatus comprising a plurality of separators configured to forward a plurality of optical signals from a plurality of optical network terminals (ONTs) along a plurality of single mode waveguides, a mode coupler coupled to the single mode waveguides and configured to receive the optical signals from the plurality of separators and combine the optical signals into a multi-mode waveguide, and an optical receiver coupled to the mode coupler via the multi-mode waveguide and configured to detect the optical signals. Also disclosed is a method comprising receiving a plurality of single mode optical channels, coupling the single mode optical channels into a multimode channel, and detecting the optical modes corresponding to the channels in the multimode channel.

Abstract: In an analog, fiber-based signal distribution system, a periodic electrical signal is frequency-multiplied by a factor of N, is converted to an optical signal, is optically amplified, is split among one or more optical fibers, is delivered by fiber to one or more remote units, is converted back to an electrical signal, is frequency-divided by the factor of N back to its original frequency, and can be used to generate synchronized clock signals at the remote units. The optical amplifier imparts a phase noise that is relatively independent of frequency, so that the phase noise contribution from the optical amplifier is advantageously decreased when the frequency divider reduces the frequency of the electrical signal. Compared to a distribution system that does not increase, then decrease, the frequency by a factor of N, the phase noise contribution from the optical amplifier is reduced by 20 log 10(N).

Abstract: An optical transmission apparatus receives an optical signal of an optical wavelength. The optical transmission apparatus has a variable wavelength filter, a neighboring frequency detection unit, and an ADC/DSP. The variable wavelength filter detects a neighboring of another optical transmission apparatus that receives an optical signal of a wavelength different from the wavelength. The neighboring frequency detection unit determines whether or not a second frequency supported by the another optical transmission apparatus where a neighboring has been detected by the variable wavelength filter is different from a first frequency supported by the optical transmission apparatus. The ADC/DSP changes a parameter for removing a phase noise from the optical signal of the wavelength according to a difference between the first frequency and the second frequency when it is determined that the second frequency is different from the first frequency.