Abstract: Within a modulator driver, different blocks are employed, e.g. a buffer, one or more variable gain amplifiers (VGA), and a final driver stage. Each of these blocks has an optimum bias point for best performance; however, interconnecting the blocks requires sharing the DC bias points in their interface, which does not necessarily match the optimum performance bias point of each block. Accordingly, a first offset feedback loop extending from reference points after a selected one of the blocks to an input of one of the blocks. The first offset feedback loop includes current sources capable of delivering a variable current to the input of the selected block in order to compensate any offset in an amplified differential input electrical signal measured at the reference points. A first bias feedback loop is also provided, including a current sinker for subtracting excess current introduced in the first offset compensation feedback loop.

Abstract: The present disclosure provides a visible light communication transmitter, a visible light communication receiver, a visible light communication system, and a method of visible light communication, which are suitable for colour shift keying (CSK), as well as providing a method of CSK. The transmitter comprises at least six graphene-based light emitting devices of different peak transmission wavelengths from each other. The receiver comprises a corresponding number of graphene-based photodetectors of different peak reception wavelengths from each other. A system according to the disclosure comprises such a transmitter and such a receiver, wherein each respective one of the different peak reception wavelengths of the six graphene-based photodetectors corresponds to a respective one of the different peak transmission wavelengths of the graphene-based light emitting devices. Such a system allows a method of visible light communication with a colour constellation of at least six base colours.

Abstract: A transmitter for a quantum communication system, comprising: a photon source unit comprising a photon source; a first intensity modulator, configured to receive an input light pulse from the photon source unit, the first intensity modulator comprising: a first element, configured to split the input light pulse into two components; a phase modulator, configured to apply a phase shift between the two components; and a second element, configured to interfere the two components; wherein at least one of the first element and the second element is asymmetric.

Abstract: A coupling module can be used to communicate high speed signals between an optical transceiver and a processing module of an optical communication device, such as an optical line termination (OLT) or an optical network unit (ONU). The coupling module can adjust the common mode voltage level of a differential signal output by the optical transceiver to the common mode voltage level required by the processing module. In addition, the coupling module splits each of the differential output signals from the optical transceiver and passes the split signals to both a high-pass filter and a low-pass filter that are connected in parallel. The outputs of the high-pass filter and the low-pass filter from different paths of the differential signal are cross-coupled and combined to provide a differential signal to the processing module.

Abstract: Systems and methods include managing optical spectrum in an optical network utilizing a flexible grid where each channel in the optical network has a center frequency and utilizes a plurality of bins to define spectral width, wherein each channel's occupancy on the optical spectrum is enumerated by its center frequency and plurality of bins.

Abstract: Methods and systems for a silicon-based optical phase modulator with high modal overlap may include, in an optical modulator having a rib waveguide in which a cross-shaped depletion region separates four alternately doped sections: receiving an optical signal at one end of the optical modulator, modulating the received optical signal by applying a modulating voltage, and communicating a modulated optical signal out of an opposite end of the modulator. The modulator may be in a silicon photonically-enabled integrated circuit which may be in a complementary-metal oxide semiconductor (CMOS) die. An optical mode may be centered on the cross-shaped depletion region. The four alternately doped sections may include: a shallow depth p-region, a shallow depth n-region, a deep p-region, and a deep n-region. The shallow depth p-region may be electrically coupled to the deep p-region periodically along the length of the modulator.

Abstract: Disclosed herein are techniques, methods, structures and apparatus that provide a silicon photonics multicarrier optical transceiver wherein both the transmitter and receiver are integrated on a single silicon chip and which generates a plurality of carriers through the effect of an on-chip modulator, amplifies the optical power of the carriers through the effect of an off-chip amplifier, and generates M orthogonal sets of carriers through the effect of an on-chip basis former.

Abstract: An optical line terminal or an optical network unit first obtains link communication quality of both a first physical link and a second physical link between the optical line terminal and the optical network unit, performs FEC encoding on the first physical link by using a first FEC code, and performs FEC encoding on the second physical link by using a second FEC code. The link communication quality of the first physical link is higher than that of the second physical link, and encoding performance of the second FEC code is higher than that of the first FEC code. Based on the foregoing technical solutions, a FEC encoding type may be selected flexibly based on communication quality of different physical links. FEC encoding having relatively low FEC encoding performance is used for a link in a good state, to reduce overheads, bandwidth, and energy consumption.

Abstract: A method (C) for converting a data signal (U). The method comprises processes of (i) providing an input bit stream (IB) of input bits (IBj), the input bit stream (IB) being representative for the underlying data signal (U) to be converted, and (ii) applying to consecutive disjunct partial input bit sequences (IBk) of a number of k consecutive input bits (IBj) covering said input bit stream (IB) a distribution matching process (DM) to generate and output a final output bit stream (OB) or a preform thereof. The distribution matching process (DM) is formed by a quadrant constellation shaping process (QS) and configured to map a respective partial input bit sequence (IBk) to a constellation point of a four-dimensional 24·m-QAM constellation—in particular conveying two distinct polarizations for each of an in-phase and a quadrature component—with I and m being fixed natural numbers and with k and m fulfilling the relation 4·m?k.

Abstract: An electro-optic device may include a Mach-Zehnder modulator (MZM) and one or more components. The one or more components may apply a DC bias with dither to a first branch and a second branch of the MZM and to arms of the first branch, and may determine a second harmonic of a first return signal. The one or more components may apply a DC bias with phase-shifted dither to the first branch and the second branch or to the arms of the first branch, and determine a second harmonic of a second return signal. The phase-shifted dither may be out of phase from the dither and have a frequency that matches a frequency of the dither. The one or more components may determine whether arms of the second branch of the MZM are operating at null, and may selectively adjust DC biases applied to the arms of the second branch.

Abstract: Methods and systems for waveguide delay based equalization with current and optical summing in optical communication are disclosed and may include an optoelectronic receiver including a directional coupler, two or more photodetectors, and one or more current mirrors. The optoelectronic receiver may be operable to: receive an input optical signal; split the input optical signal into first and second optical signals using the directional coupler; generate a first electrical from the first optical signal using a first photodetector; generate a second electrical signal from the second optical signal using a second photodetector; mirror the second electrical signal using the current mirror; and sum the first electrical signal with the amplified second electrical signal. The optoelectronic receiver may be operable to delay the first optical signal before generating the first electrical signal, using a waveguide delay.

Abstract: A transmitter. In some embodiments, the transmitter has an electrical input and an optical output. The transmitter may include a light source; an optical amplitude modulator having an optical input connected to the light source, a modulation input connected to the electrical input, and an output; and a first gated optical comparator, having a sampling clock input, an analog input connected to the output of the optical amplitude modulator, and an output. The first gated optical comparator may be configured to generate, for each cycle of an optical sampling clock signal received at the sampling clock input, a one-bit digital representation of an analog optical signal received at the analog input.

Abstract: Provided is an optical transmission method including: executing mapping processing (112) so that information of one unit of one system, or one unit of each of a plurality of systems, is mapped in a pattern of two or more Stokes vectors orthogonal between slots of a multi-time slot; generating an optical signal from an electric signal processed by the mapping processing; and transmitting the optical signal. A reception side receives the optical signal and converts the received optical signal into an electric signal, and executes de-mapping processing (322) for conversion into the information of one unit of one system, or one unit of each of a plurality of systems, by selecting high-likelihood bit information in association with the mapping processing in which the information is mapped in the pattern of Stokes vectors orthogonal between the slots of the multi-time slot.

Abstract: The present disclosure generally pertains to signal analysis systems and methods for measuring and characterizing signal attributes, such as noise. A signal analysis system comprises an optical receiver that receives an optical signal and converts the received signal into an electrical signal. A programmable frequency divider divides the frequency of the incoming electrical signal at different division ratios, and a signal analyzer analyzes the resulting signal. In this regard, by increasing the division ratio of the frequency divider and measuring the power spectral density with the signal analyzer at different division ratios, a suitable signal for determining different parameters (e.g., modulation frequency and modulation index) may be found.

Abstract: Disclosed is an optical line terminal (OLT), including: N tunable modules, each of the N tunable modules include M tunable transmitters, the number of tuning channels of the M tunable transmitters is greater than or equal to two and the number of the tuning channels is less than M×N, wherein N and M are integers greater than or equal to two.

Abstract: An optical end terminal in which protection switching is implemented by using (i) the optical data receiver thereof for detecting a path failure and (ii) the optical data transmitter thereof for signaling the detected path failure to the protection-switching circuit. In an example embodiment, the optical data receiver is configured to detect a path failure based on the presence of certain data-recovery errors. The optical data transmitter is operatively connected to the optical data receiver and configured to generate an in-band dither tone of a predetermined frequency in response to such failure detection. The protection-switching circuit is configured to (i) detect dither tones in the optical signals passing therethrough and (ii) connect the optical data receiver to the protection path instead of the working path in response to detecting the dither tone of the predetermined frequency.

Abstract: An optical receiver includes a transimpedance amplifier that converts a current signal corresponding to an optical signal into a voltage signal. The transimpedance amplifier includes an input terminal receiving the current signal, an output terminal outputting the voltage signal, an inverting circuit including a pull-up device that pull-up drives the voltage signal of the output terminal according to the current signal, and a pull-down device that pull-down drives the voltage signal of the output terminal according to the current signal, a feedback resistor electrically connected between the input and output terminals, a first resistor electrically connected between the input terminal and the pull-up device, and a second resistor electrically connected between the input terminal and the pull-down device.

Abstract: Methods and systems for a distributed optical transmitter with local domain splitting is disclosed and may include, in an optical modulator integrated in a silicon photonics chip: receiving electrical signals, communicating the electrical signals to domain splitters along a length of waveguides of the optical modulator utilizing one or more delay lines, and generating electrical signals in voltage domains utilizing the domain splitters for modulating the optical signals in the waveguides of the optical modulator by driving diodes with the electrical signals generated in the voltage domains. The delay lines may comprise one delay element per domain splitter, or may comprise a delay element per domain splitter for a first subset of the domain splitters and more than one delay element per domain splitter for a second subset of the domain splitters.

Abstract: A telemetry system is operable to transmit data by bridging the low signal bandwidth available to high temperature electronics with the high spectral bandwidth available in optical fiber. A transmitter, such as a frequency comb, generates light to a fiber and the light is demultiplexed to separate the light into separate wavelengths. Modulators encode downhole data onto each wavelength and a multiplexer recombines the wavelengths onto a single fiber that passes the light back to the surface where a second demultiplexer separates the light to be transmitted to distinct receivers that detect the encoded data. A dual fiber system may also be utilized. One or more commands may also be transmitted to the downhole tools by transmitted the encoded command to a coupler that is coupled to a multiplexer where a downhole receiver determines the downhole tool that should receive the associated command.

Abstract: Digital information can be carried on the fiber leg of an access network using binary modulation. Binary modulated data received at an O/E node can then be modulated onto an analog waveform using quadrature amplitude modulation or some other technique for modulating an analog waveform and transmitted over, for example, the coaxial leg of the network. The O/E node may also receive an analog signal, over the coaxial leg, modulated to carry upstream data from subscriber devices. The O/E node may demodulate the upstream signal to recover the upstream data and forward that upstream data over the fiber leg using a binary modulated optical signal.