Abstract: In order to further develop a circuit arrangement (CR; CR?) for receiving optical signals (SI) from at least one optical guide (GU), said circuit arrangement (CR; CR?) comprising: at least one light-receiving component (PD) for converting the optical signals (SI) into electrical current signals (IPD), at least one transimpedance amplifier (TA), being provided with the electrical current signals (IPD) from the light-receiving component (PD), at least one automatic gain controller (AG) for controlling the gain or transimpedance (R) of the transimpedance amplifier (TA), at least one integrator (IN) in a feedback path (FP), said integrator (IN) generating a control signal (Vint), at least one voltage-controlled current source (CS), being provided with the control signal (Vint) from the integrator (IN), at least one limiter (LI) acting as a comparator and generating in its output a logic level for positive or negative voltages in its input, and a corresponding method in such a way that a multilevel optical lin

Abstract: An electro-optical oscillator includes, in part, a modulator, a signal splitter, N photodiodes with N being an integer greater than one, a signal combiner, and a filter. The modulator modulates an optical signal in accordance with a feedback signal. The splitter splits the modulated optical signal into N optical signals each delivered to a different one of N photo-diodes. Each of the N photo-diodes converts the optical signal it receives to a current signal. The signal combiner combines the N current signals received from the N photo-diodes to generate a combined current signal. The filter filters the combined current signal and generates the feedback signal. The electro-optical oscillator optionally includes, in part, N variable optical gain/attenuation components each amplifying/attenuating a different one of the N optical signals generated by the splitter.

Abstract: Slots (311) for transmission of data of a particular transmission type over an optical network are allocated by selecting a first available slot (313_2) at an ordinal position corresponding to a multiple of n and allocating the selected first available slot and the next n?1 consecutive slots (313_4, 313_5) from the selected first available slot (313_3), if all n?1 consecutive slots (313_4, 313_5) are available, for transmission of data of the particular transmission type. The data is transmitted over an optical network comprising a plurality of nodes (305, 327) interconnected by optical sections (301, 309, 329, 331) the nodes (305, 327) supporting a plurality of transmission types, wherein transmission of data of the particular transmission type requires a predetermined number n of consecutive slots. Alternatively the slots may be divided in groups (333, 335, 337) and slots are allocated to a group in which all slots are available.

Abstract: A laser-based device or sensor includes: a first laser transmitter having a first self-mix carrier frequency; a second laser transmitter having a second, different, self-mix carrier frequency; a first monitor photodiode to receive a first optical signal from the first laser transmitter, and to output a first electric signal; a second monitor photodiode to receive a first optical signal from the second laser transmitter, and to output a second electric signal; an electric connection to connect together the first electric signal and the second electric signal, forming a combined electric signal; a single laser receiver to receive the combined electric signal and to generate from it a spectrum that corresponds to both (i) optical feedback of the first laser transmitter, and (ii) optical feedback of the second laser transmitter. Alternatively, a single monitor photodiode is used, receiving optical signals from multiple laser transmitters, and outputting a single electric signal to a single laser receiver.

Abstract: A laser-based device or sensor includes: a first laser transmitter having a first self-mix carrier frequency; a second laser transmitter having a second, different, self-mix carrier frequency; a first monitor photodiode to receive a first optical signal from the first laser transmitter, and to output a first electric signal; a second monitor photodiode to receive a first optical signal from the second laser transmitter, and to output a second electric signal; an electric connection to connect together the first electric signal and the second electric signal, forming a combined electric signal; a single laser receiver to receive the combined electric signal and to generate from it a spectrum that corresponds to both (i) optical feedback of the first laser transmitter, and (ii) optical feedback of the second laser transmitter. Alternatively, a single monitor photodiode is used, receiving optical signals from multiple laser transmitters, and outputting a single electric signal to a single laser receiver.

Abstract: A system and method for adaptive equalization in a communication system. The system can include a modulator, a processor coupled to the modulator, and a memory coupled to the processor. The memory can store software instructions that, when executed by the processor, cause the processor to perform operations that can include generating, for each of one or more scan frequencies of interest, an optimal bias setting of the modulator. Data indicating a selection of a range of frequencies to be processed by the communication system can be received at the processor. The operations can include determining, responsive to the receiving, the optimal bias setting corresponding to the selected range of frequencies. A bias of the modulator can be adjusted based on the determined optimal bias setting, the adjusting providing adaptive equalization of the flatness response of the communication system.

Abstract: A high-speed optical receiver implemented using a low-speed light receiving element is provided, which is configured to receive an optical signal having a higher transmission rate than that received using a general avalanche photo diode (APD) by expanding a frequency bandwidth using a receiver circuit configured together with an APD in the optical receiver including the APD, an APD bias control circuit, a transimpedance amplifier (TIA) for amplifying a signal received from the APD to have low noise, and a post amplifier; and a method of implementing such a high-speed optical receiver.

Abstract: An optical communication system with a hierarchical branch configuration. The system includes first and second cable landing stations coupled to a trunk path in an optical cable. At least one hub-node is coupled to the trunk path through an associated hub-node branching unit. Sub-nodes are coupled the hub-nodes through associated sub-node branching units and sub-node paths in the optical cable. Sub-node signals may be communicated between the sub-nodes and the hub-nodes without being provided on the trunk path.

Abstract: Techniques are described for characterizing a receiver front end of a pluggable optical module. The pluggable optical module receives an optical signal that includes a first portion having a first polarization and a second portion having a second polarization. The first portion and second portion are not coherent with one another and the power of the first portion and second portion is equal.

Abstract: An optical communication device including a plurality of groups of light emitting diode (LED) groups that are turn on according to a control of a lighting and communication control module. The lighting and communication control module is configured to receive an AC input voltage, generate a rectified voltage from the AC input voltage, determine a voltage level of the rectified voltage, sequentially drive the plurality of LED groups according to the voltage level of the rectified voltage, and perform optical communication through the plurality of LED groups only when the voltage level of the rectified voltage is greater than or equal to a preset threshold voltage level.

Abstract: A communications device is disclosed and includes: a first acquiring unit for acquiring first specific wavelength light and second specific wavelength light from a first optical path; a first receiving unit for converting the first specific wavelength light coming from the first acquiring unit into a first electrical signal; a first control unit for sending a first modulating signal to a first loopback unit according to the first electrical signal coming from the first receiving unit; and the first loopback unit for modulating the second specific wavelength light coming from the first acquiring unit according to the first modulating signal, and looping the modulated second specific wavelength light back to a second optical path, where a transmission direction of an optical signal in the second optical path is opposite to a transmission direction of an optical signal in the first optical path. The present invention further discloses a communications method.

Abstract: An optical transmission system includes: a first optical transmission device configured to transmit measurement light to an optical transmission line on a first direction; and a second optical transmission device configured, when an optical transmission characteristic is measured, to loop-back the measurement light received from the first optical transmission device through an optical transmission line on the first direction and to transmit the measurement light to the first optical transmission device through an optical transmission line on a second direction, wherein, when the optical transmission characteristic is measured, the first optical transmission device receives the measurement light loop-backed by the second optical transmission device and measures the optical transmission characteristic between the first optical transmission device and the second optical transmission device.

Abstract: An optical transmission and reception system includes a transmitter and receiver. The transmitter differentially encodes control information to generate a differentially coded signal; uses the differentially coded signal to modulate a signal sequence in which electricity concentrates at a particular frequency; applies time-division multiplexing on the modulated signal sequence and a primary signal in one of two polarized wave components, and applies time-division multiplexing on the other polarized wave components and the signal sequence itself; and polarization-multiplexes the both of the time-division multiplexed polarized waves into an optical signal; and transmits the optical signal to the receiver.

Abstract: A DP-QPSK optical transmitter includes an outer MZM comprising a first parent MZM comprising a first child MZM and a second child MZM that modulates a QPSK signal with a first polarization. A second parent MZM includes a first child MZM and a second child MZM that modulates a QPSK signal with a second polarization. The outer Mach-Zehnder modulator multiplexes the first and second polarization embedded into a dual-polarization QPSK signal generation. A first optical detector detects the QPSK signal generated by the first parent MZM with the first polarization. A second optical detector optical detects the QPSK signal generated by the second parent Mach-Zehnder modulator with the second polarization. A bias control circuit generates bias signals on at least one output that stabilize the DP-QPSK signal in response to signals generated by the first and second optical detector using electrical time division multiplexing.

Abstract: The disclosed coherent optical receiver includes a local light source; a 90-degree hybrid circuit; an optoelectronic converter; an analog-to-digital converter; a skew addition unit; and a FFT operation unit. The 90-degree hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs multiple optical signals separated into a plurality of signal components. The optoelectronic converter detects the optical signal and outputs a detected electrical signal. The analog-to-digital converter digitizes the detected electrical signal and outputs a detected digital signal. The skew addition unit adds to the detected digital signal an additional skew amount whose absolute value is equal to, whose sign is opposite to a skew amount of a difference in propagation delay in each lane connected to each output channel of the 90-degree hybrid circuit. The FFT operation unit performs a fast Fourier transform on the output from the skew addition unit.

Abstract: An optical transmitter that narrows the linewidth of its output light is disclosed. The optical transmitter includes a wavelength tunable laser diode (LD) known as a CSG-DR LD integrated with a semiconductor optical amplifier (SOA) driven in a constant magnitude mode. The wavelength of the light output from the LD is determined by transmission through an etalon filter. The optical transmitter feeds the output of the etalon filter back to an injection current supplied to the LD to reduce phase noise inherently contained in the output light.

Abstract: An optical communication system, a linear optical receiver, and an Integrated Circuit (IC) chip are disclosed, among other things. One example of the disclosed IC chip includes a transimpedance amplifier that receives an input electrical signal from a photodiode and provides an amplified version of the input electrical signal as an output, at least one variable gain amplifier that receives the amplified electrical signal output by the transimpedance amplifier and a bandwidth control mechanism that extends a bandwidth of the second amplified output at a maximum gain of the second amplification phase and also reduces a peaking of the second amplified output at a minimum gain of the second amplification phase.

Abstract: A matrix M is used to determine groups of potential regenerator placements and obtain potential end-to-end optical paths by selecting desired sequences of regenerators. Then, a hierarchical guided search may be employed to efficiently select desired N-tuple disjoint optical paths from the potential optical paths. The hierarchical guided search may employ a search graph and a search tree to guide the search and to eliminate candidate nodes and optical paths early in the search process.

Abstract: An optical communication technique transmits an optical signal at a higher bit rate using an optical transceiver interface couplable to a set of optical transmitters, each operating at a lower bit rate over a plurality of channels, by demultiplexing the optical signals from the transmitters such that some of the resulting optical signals have wavelengths that are specified as center wavelengths by an optical communication standard for the lower bit rate optical transmission and the rest of the resulting optical signals have wavelengths offset from the specified center wavelengths, then multiplexing the resulting optical signals into the higher bit rate optical signal. Related optical communication techniques involve using the reciprocal method to receive the higher bit rate optical signal and to produce multiplexed optical signals at the lower bit rate.

Abstract: A gain-variable trans-impedance amplifier (TIA) in optical device is disclosed. The TIA has an improved dynamic range for receiving electrical signals and is configured to convert current signals from an avalanche photodiode (APD) to voltage signals. A resistor element is between the input and output terminals of the TIA, wherein the resistance of the resistor element can regulate the resistance and/or impedance value of the TIA, and a switch determines or controls the resistance of the resistor element. When the power of an optical signal received by the APD is higher than a predetermined value, the resistance becomes smaller and the gain of the TIA becomes greater. When the power of the optical signal is lower than the predetermined value, the resistance becomes greater. The gain of the TIA is automatically adjusted on the basis of the intensity of received optical signals to obtain a greater dynamic operational range.