Abstract: An exemplary technique is provided for a coherent optical receiver adapted to receive an optical signal transmitted over an optical transmission channel exhibiting Cross-Polarization Modulation (XPOLM). The received optical signal comprises a first polarization component and a second polarization component.

Abstract: An optical transmission/reception system includes a modulator for modulating light based on data to output signal light; a transmission-side signal processor performing transmission-side digital signal processing which imparts a polarization change to the signal light by the optical modulation with respect to an input signal; an optical transmitter in which the modulator performs the optical modulation based on the input signal subjected to the transmission-side digital signal processing in the transmission-side signal processor; and an optical receiver including a converter converting the signal light inputted from the optical transmitter via a transmission path to a digital electric signal for each polarization component, and a reception-side signal processor performing reception-side digital signal processing which imparts a polarization change having a property substantially inverse to a property of the polarization change in the transmission-side signal processor with respect to the digital electric sign

Abstract: An optical digital coherent receiver includes: a polarization separation circuit configured to perform polarization separation on a received signal and output polarized signals; and a determination circuit configured to trigger a start of digital signal processing in a stage subsequent to the polarization separation circuit when it is determined that a distribution of a peak of an amplitude of one of the polarized signals has a characteristic corresponding to a modulation method used on a transmitting side.

Abstract: Techniques for timing synchronization in an optical orthogonal frequency division multiplexing (OOFDM) system includes providing a time-domain training symbol having a symmetric distribution and producing the training symbol by transmitting a real-valued PN sequence on each subcarrier under the OOFDM. The training sequence includes an initial value, followed by an odd length palindromic sequence of values.

Abstract: A polarization state of a transmission signal can be changed at a high speed based on a symbol-rate By switching a first switch, a second switch, and a third switch with time, one of an X-polarized wave_I-signal as a Y-polarized wave_I-signal, a signal caused by performing logical inversion for an X-polarized wave_I-signal, an X-polarized wave_Q-signal and a signal caused by logical inversion for an X-polarized wave_Q-signal is input to a second modulator. Further, by switching the first switch, the second switch and the third switch with time, the second modulator is input one of the X-polarized wave_I-signal as the Y-polarized wave_Q-signal, the X-polarized wave_I-signal, the signal caused by performing logical inversion for the X-polarized wave_I-signal, the X-polarized wave_Q-signal and the signal caused by performing logical inversion for the X-polarized wave_Q-signal. Thereby, a polarization state of a transmission signal can be changed at high speed based on a symbol-rate speed.

Abstract: A novel terrestrial wireless communications technique for terrestrial portable terminals including hand-held mobile devices and fixed wireless instruments, utilizing a spoke-and-hub communications system, having a plurality of individual hubs and/or base-stations all in communications with the portable terminals. The portable terminals and the hubs are assigned to use incompatible polarity formats in terms of circularly polarity (CP) and linearly polarity (LP). In forward links, a signal processed by the LP ground telecommunications hubs is radiated through multiple antennas with various LP polarities to an individual CP user simultaneously. The multiple paths are organized via assignments of a plurality of polarities, frequency slots, and directions by wavefront multiplexing/demultiplexing techniques such that the same communications assets including frequency spectrum may be re-used by other users. The same polarity diversity methods can be extended to peer-to-peer communications.

Abstract: The present disclosure provides systems and methods for the compensation of signal distortion in fiber optic communication systems and the like. More specifically, the present disclosure provides an orthogonal polarization detection and broadband pilot (OPDBP) technique for the compensation of nonlinear cross polarization (i.e. nonlinear cross polarization modulation) (XPolM) induced noise and nonlinear nonlinear cross phase modulation (XPM) induced noise in a high data rate polarization multiplexed (PM) multilevel-quadrature amplitude modulated (M-QAM) channel due to neighboring channels. This approach allows for the compensation of both XPolM and XPM simultaneously, providing several dBs of optical reach extension. The approach uses a pilot tone based orthogonal polarization detection scheme with broadband (i.e. a few GHz wide) filtering of the pilot tones.

Abstract: A received POLMUX signal is rotated by fixed rotation parameters (Rot0, Rot1, Rot2) and the rotated POLMUX signal with optimal signal performance is selected and phase information is derived from both polarities. A pre-filter improves the timing accuracy.

Abstract: An improved method and apparatus for reducing performance degradation in optical fiber transmission system due to polarization mode dispersion and nonlinear polarization coupling. Digital polarization scrambling with transmit and receive digital signal processing is used to reduce these effects. By performing digital polarization scrambling on all possible states of polarization with respect to the two principle axes of an optical fiber, the SOP dependent penalty is averaged out. The invention also provides a method and apparatus for performing digital polarization scrambling on the transmit side and blinded polarization tracking or synchronized polarization descrambling at the receive side. Using a configurable scrambling speed, the invention works as a polarization scanner low speed SOP rotation or as a scrambler at fast SOP rotation speeds.

Abstract: The present disclosure provides systems and methods for noise tolerant signal processing in a pilot assisted data receiver, including: given received pilots with common pilot components and individual pilot components, computing coefficients associated with the individual pilot components of the received pilots; and applying the computed coefficients to the received pilots to obtain conditioned pilots. The individual pilot components result from relatively slow changes of the received pilots relative to the common pilot components. The common pilot components result from relatively fast changes of the received pilots relative to the individual pilot components.

Abstract: Methods and systems for mitigating effects of polarization dependent loss (PDL) in an optical network transmitting a multi-carrier optical signal comprising a plurality of subcarriers may involve assigning and modifying a state of polarization to each subcarrier prior to transmission. An assigned state of polarization for each subcarrier may be modified for the subcarrier in the digital domain and/or the optical domain. Various specific assignment methods may be used, including individual subcarrier assignment, subcarrier set assignment, arbitrary subcarrier group assignment, random assignment, and/or combinations thereof. The assigned states of polarization may be selected based on a resulting minimum PDL-induced peak-to-peak power variation over a sum of the subcarriers for all orientations of a principal axis of PDL.

Abstract: Using polarization modulation techniques to simultaneously transmit two different data streams (formatted according to two different protocols) over a single optical wavelength. A first data stream that is encapsulated for transport using a first transport protocol, and a second data stream that is encapsulated for transport using a second transport protocol are received. The first data stream is modulated on a wavelength with a first polarization mode of a polarization division modulation scheme to produce a first modulated data stream and the second data stream is modulated on the wavelength with a second polarization mode of the polarization division multiplex transmission scheme to produce a second modulated data stream having the second polarization mode. The second polarization mode is orthogonal to the first polarization mode. The first and second data streams are combined onto a single wavelength for transmission over a single optical fiber using a polarization beam combiner.

Abstract: A method and apparatus for suppressing pump-mode optical beat interference noise in a Raman amplified fiber link of an optical network, wherein a wavelength of a laser beam generated by a first pump laser and a wavelength of a laser beam generated by a second pump laser of a pair of polarization multiplexed pump lasers are detuned with respect to each other to suppress the optical beat interference, OBI, noise in the Raman amplified fiber link of said optical network.

Abstract: A system, e.g. for optical communication, includes an I-Q modulator and a transmission signal processor. The I-Q modulator is configured to modulate a first light source in response to first I and Q modulation signals. The transmission signal processor is configured to receive a data stream including data corresponding to a first data subchannel. The processor maps the data subchannel to an optical transmission subchannel and outputs the first I and Q modulation signals. The I and Q modulation signals modulate the light source to produce an optical transmission signal that includes wavelength components corresponding to the optical transmission subchannel.

Abstract: An optical transmission apparatus includes: an optical amplifier configured to amplify a wavelength multiplexing light to be transmitted, the wavelength multiplexing light being input thereto; a combining unit configured to combine a plurality of non-signal lights in such a way that angles formed between polarization planes of the plurality of non-signal lights of a wavelength of wavelengths belonging to an amplification band of the optical amplifier become equal, the wavelength being different from a wavelength of a polarization multiplexing signal light; and a wavelength multiplexer configured to generate the wavelength multiplexing light to be input to the optical amplifier by multiplexing the plurality of non-signal lights combined by the combining unit and the polarization multiplexing signal light.

Abstract: Embodiments of the present invention provide a method, an apparatus, and a system for processing an optical network signal. The method includes: receiving an optical signal sent by an optical line terminal, where the optical signal includes two polarization components perpendicular to each other, and downlink data is modulated on one of the polarization components; dividing the optical signal into two signals, where each signal is the optical signal; demodulating the downlink data from one optical signal and performing, for the other optical signal, vertical polarization rotation processing and processing of modulating uplink data onto two polarization components of the optical signal; sending the other optical signal on which the vertical polarization rotation processing and the uplink data modulation processing are performed to the optical line terminal. With the embodiments of the present invention, signal processing load of the optical network unit and the optical line terminal can be lowered.

Abstract: An optical add/drop multiplexer including one or more optical drop multiplexers connected in free space or fused by optical fiber pigtails, a wavelength blocker with an input port connected to an output port of the optical drop multiplexer through the fusion of the fiber pigtails, one or more optical add multiplexers connected in free space or fused by fiber pigtails, a digital signal processor, an analog-to-digital signal converter, a digital-to-analog converter, and a plurality of electronic control and feedback loops for tuning and scanning an optical wavelength.

Abstract: Blind polarization demultiplexing algorithms based on complex independent component analysis (ICA) by negentropy maximization for quadrature amplitude modulation (QAM) coherent optical systems are disclosed. The polarization demultiplexing is achieved by maximizing the signal's non-Gaussianity measured by the information theoretic quantity of negentropy. An adaptive gradient optimization algorithm and a Quasi-Newton algorithm with accelerated convergence are employed to maximize the negentropy. Certain approximate nonlinear functions can be substitutes for the negentropy which is strictly derived from the probability density function (PDF) of the received noisy QAM signal with phase noise, and this reduces the computational complexity.

Abstract: A signal processing method, an optical receiver and optical network system is provided. The method includes: receiving a first optical signal sent by an optical network unit, generating a second optical signal and modulating a phase of the second optical signal, obtaining at least one path of electrical signals after the first optical signal and the second optical signal separately undergo polarization splitting, frequency mixing, and optical-electrical conversion, outputting a third electrical signal after performing operation processing on the at least one path of electrical signals, and restoring a data signal according to the third electrical signal and performing sending. The embodiments example benefits are greatly reducing complexity of system implementation and maximally reducing a system upgrade cost and an optical power loss.

Abstract: A transmitter for an optical telecommunication system on a weakly multimode fiber is disclosed. One aspect is a transmitter including an encoder transforming each block of symbols to be transmitted into a code matrix, each element of the matrix being relative to a time of use and to a propagation mode of the weakly multimode fiber. The transmitter can include a plurality of modulators respectively associated with the different propagation modes, each modulator modulating a laser beam during a time of use. Each modulator can modulate a laser beam by use of an element of the corresponding matrix, the elements of the matrix of the code being subjected beforehand to an OFDM modulation upstream of said modulators. Each of the modulated beams can be input into the weakly multimode fiber to propagate therein according to a separate mode.

Abstract: Disclosed are structures and methods for generating a Nyquist superchannel.

Abstract: An apparatus comprises a coherent optical transmitter. The coherent optical transmitter comprises a first modulator for generating a first polarization, a second modulator for generating a second polarization, and a symbol interleaver configured to receive a first symbol stream intended to be transmitted on a first polarization and a second symbol stream intended to be transmitted on a second polarization, to direct one portion of symbols of the first symbol stream to the first modulator for modulation onto the first polarization and another portion of the symbols of the first symbol stream to the second modulator for modulation onto the second polarization, and to direct one portion of symbols of the second symbol stream to the first modulator for modulation onto the first polarization and another portion of the symbols of the second symbol stream to the second modulator for modulation onto the second polarization.

Abstract: The present disclosure provides systems and methods for the compensation of signal distortion in fiber optic communication systems and the like. More specifically, the present disclosure provides an orthogonal polarization detection and broadband pilot (OPDBP) technique for the compensation of nonlinear cross polarization (i.e. nonlinear cross polarization modulation) (XPolM) induced noise and nonlinear nonlinear cross phase modulation (XPM) induced noise in a high data rate polarization multiplexed (PM) multilevel-quadrature amplitude modulated (M-QAM) channel due to neighboring channels. This approach allows for the compensation of both XPolM and XPM simultaneously, providing several dBs of optical reach extension. The approach uses a pilot tone based orthogonal polarization detection scheme with broadband (i.e. a few GHz wide) filtering of the pilot tones.

Abstract: To, even when a transmission wavelength varies in each ONU and an optical amplifier gain depends on the wavelength in an OLT equipped with an optical amplifier, prevent the optical amplifier gain from varying in every ONU and thus prevent deterioration of a dynamic range. The OLT estimates a transmission wavelength of each ONU at the time of ONU registration, and retains a correspondence between an ONU identifier and the transmission wavelength. Moreover, for every burst, an injection current to the optical amplifier is adjusted based on a wavelength and optical amplifier characteristic database.

Abstract: The present invention discloses a receiving apparatus, a sending apparatus, a system and a method for optical polarization division multiplexing.

Abstract: An optical transmitting apparatus includes semiconductor laser elements. Upon receiving laser beams, a multiplexed beam is emitted from a wavelength multiplexing filter. The wavelength multiplexing filter includes a triangular prism and a wavelength multiplexing filter film. A front end face and a rear end face of the prism are not parallel to each other so that a prism angle at which a surface parallel to the front end face intersects a surface parallel to the rear end face, is an acute angle. The prism angle is the angle at which the laser beam impinging from the front end face into the triangular prism is reflected by the wavelength multiplexing filter film toward the front end face and the multiplexed beam is directed to the optical axis side of the optical fiber.

Abstract: A received optical signal is coherently demodulated and converted into electrical complex samples (p(n); (px(n), py(n)), which are dispersion compensated in a compensation filter (11). A control circuit (12, 13, 14, 15) calculates comparison values (R1, R2) from corrected samples q(n) and an estimated error value (?MIN). A plurality of compensation function (T(M)) is applied according to a predetermined dispersion (CD) range and after a second iteration is the compensation filter (11) set to an optimum compensation function (T(M)).

Abstract: A compensator device may include a selection switch to receive a first optical signal and provide first and second groups of channels associated with the first optical signal; a polarization beam splitter to receive the first channels, and provide first and second components; a photodiode that provides an electrical signal indicative of an intensity of the first group of channels; a first modulator to receive the electrical signal and the first components and to modulate the first components to form first modulated channels; a second modulator to receive the electrical signal and the second components to modulate the second components to form second modulated channels; a polarization beam combiner to receive the first and second modulated channels to form combined modulated channels; and a coupler to receive the combined modulated channels and the second group of channels to form a second optical signal.

Abstract: Signal processing means includes carrier compensation means for compensating for a phase difference and a frequency difference between signal light and local light in relation to two polarization signals, so as to generate two carrier compensated signals, symbol determination means for demodulating the two carrier compensated signals on the basis of a signal arrangement of multi-value modulation, symbol rough-determination means for demodulating the two carrier compensated signals on the basis of a signal arrangement in which the number of multi-values of the multi-value modulation is reduced, selection means for selecting either of an output of the symbol determination means and an output of the symbol rough-determination means, and coefficient setting means for updating filter coefficients of polarized wave separation means by using an output selected by the selection means.

Abstract: A method for exchanging information with an Optical Network Unit (ONU), the method comprising: receiving, by the ONU, downstream signals that comprise a pilot signal and downstream information signals; wherein the downstream information signals embed first polarization modulated information and second polarization modulated information; wherein the pilot signal is received at a pilot frequency slot and the downstream information signals are received at a downstream information frequency slot that differs from the pilot frequency slot; splitting the downstream signals to first, second, third and fourth sets of signals; wherein the splitting comprises performing a polarization based splitting to provide first and second intermediate sets of signals; wherein the first and second sets of signals originate from the first intermediate set of signals and the third and fourth sets of signals originate from the second intermediate set of signals; generating a fifth set of signals by providing the second and fourth set

Abstract: An apparatus, e.g. an optical communication system, includes an optical transmitter and an optical receiver. The transmitter includes a laser configured to provide an optical signal amplitude-modulated among M different levels, e.g. in two polarizations. The receiver is configured to demodulate the optical signal to produce a received symbol constellation including a plurality of symbol rings in a complex I-Q space.

Abstract: Methods and apparatus for line coding in a communications network are described. According to one embodiment of the invention, downstream communications traffic bits are received and mapped into downstream bit positions of a transmission structure. A pre-selected bit in each upstream bit positions of the transmission structure is provided to form a downstream transmission structure. A downstream optical signal carrying the downstream transmission structure is generated for transmission. Upstream communications traffic bits are also received and mapped into the upstream bit positions of the transmission structure to form an upstream transmission structure. An upstream optical signal carrying the upstream transmission structure is generated for transmission.

Abstract: An optical transmitter transmits a dual polarization optical Nyquist frequency domain multiplexed signal. The signal includes a first polarization component and a second polarization component. Each component comprises multiple subchannels, possibly having different subchannel bandwidths and different modulation schemes. An optical receiver receives the signal and recovers transmitted data.

Abstract: A transmission method that transmits an optical signal via a plurality of virtual lanes in dual polarization or multi-level modulation includes: receiving a first frame signal of a first frequency and a second frame signal of a second frequency, and storing the first and second frame signals on a memory; reading out the first frame signal from the memory at a third frequency, and inserting a stuff into the first frame signal such that a difference between the first frequency and the third frequency is adjusted to generate a third frame signal; reading out the second frame signal from the memory at the third frequency, and inserting a staff into the second frame signal such that a difference between the second frequency and the third frequency is adjusted to generate a fourth frame signal; and transmitting the third and fourth frame signals respectively via different virtual lanes.

Abstract: An optical transmission system includes a polarization multiplexing optical transmitter for transmitting an optical signal, where an X-polarized signal and a Y-polarized signal each having a having predetermined frame structure are polarization-multiplexed, to an optical fiber transmission path, and a polarization multiplexing receiver for receiving the optical signal that has propagated through the optical transmission path. The polarization multiplexing optical transmitter delays a frame assignment signal (FAS) in the Y-polarized signal, by a predetermined delay time ?, relative to FAS in the X-polarized signal.

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: A network device may include a polarizing multiplexing transmitter, a polarization maintaining (PM) fiber, and a polarizing demultiplexing receiver. The polarizing multiplexing transmitter may generate an optical signal, split the optical signal into a first and a second split optical signal, and modulate the split optical signals based on electrical signals to form first and second modulated optical signals. The polarizing multiplexing transmitter may polarization multiplex the first and second modulated optical signals to form a polarization multiplexed signal and transmit the polarization multiplexed signal via the PM fiber to the polarizing demultiplexing receiver. The polarizing demultiplexing receiver may polarization demultiplex the polarization multiplexed signal to form the first and second modulated optical signals and directly detect the first and the second split optical signal from the first and second modulated optical signals.

Abstract: The optical channel monitor includes a polarization adjuster, a wavelength divider, a polarization divider, a first intensity detector, and a second intensity detector. The polarization adjuster adjusts the plane of polarization of a first optical signal to a first direction and the plane of polarization of a second optical signal to a second direction. The wavelength divider divides each of the optical signals multiplexed on the first and second optical signals, in accordance with the wavelengths. The polarization divider divides each of the divided optical signals, based on the direction of the plane of polarization. The first intensity detector receives an optical signal whose direction of the plane of polarization is the first direction among the divided optical signals. The second intensity detector receives an optical signal whose direction of the plane of polarization is the second direction.

Abstract: A planar lightwave circuit and an optical receiver which reduce degradation in signal quality is provided.

Abstract: An optical transmitter includes: an optical modulator including a first modulation unit and a second modulation unit respectively configured to propagate a first optical signal and a second optical signal that are obtained by splitting input light; a signal generator configured to generate a first drive signal and a second drive signal that are respectively supplied to the first modulation unit and the second modulation unit; a phase controller configured to control a phase difference between the first optical signal and the second optical signal in the optical modulator; and a phase difference detector configured to detect the phase difference between the first optical signal and the second optical signal controlled by the phase controller. The signal generator generates the first drive signal and the second drive signal based on the phase difference detected by the phase difference detector.

Abstract: A polarization controller includes a first polarization controller, a demultiplexer, a second polarization controller, and a multiplexer. The first polarization controller controls the state of polarization of input light such that a part of the wavelength components of the input light is in a first state of polarization. The demultiplexer demultiplexes the light output from the first polarization controller into a plurality of wavelength components. The second polarization controller controls the plurality of wavelength components in a second state of polarization by using liquid crystal modulation devices. The multiplexer multiplexes the plurality of wavelength components output from the second polarization controller.

Abstract: An optical receiver having a plurality of optical IQ modulators arranged in a butterfly configuration and configured to operate as an optical polarization de-multiplexer. The optical receiver further has (i) an opto-electric circuit configured to apply optical homodyne detection to an optical input signal received by the optical receiver and (ii) a controller configured to generate one or more control signals for driving the IQ modulators of the plurality based on one or more electrical feedback signals received from the opto-electric circuit.

Abstract: A coherent optical receiver circuit is disclosed in which various components of the optical receiver may be provided or integrated, in one example, on a common substrate. Further integration is achieved by incorporating various optical demultiplexer designs that are relatively compact and conserve space on the surface of the substrate. The optical receiver circuit may be used to demultiplex quadrature phase shift keying (QPSK) optical signals.

Abstract: An optical signal transmission system comprises a transmitter that phase-modulates two optical signals of a same frequency by asymmetrically chirping the two optical signals, combines the two optical signals that have been phase-modulated as polarization components according to polarization multiplexing, and transmits an optical signal that has been combined and obtained; and a receiver that receives said optical signal from said transmitter, compresses pulses of at least one of the polarization components of the optical signal, and splits the optical signal into two polarization components.

Abstract: Methods, structures and systems for generating different polarization multiplexed signals wherein the drivers of the modulators are generic while a software-controlled manager allows the carrying of any standard 10 G/40 G/100 G data while—at the same time—being adaptively adjustable according to specific link requirements and users' requests in both dispersion-managed and uncompensated links.

Abstract: An all-optical modulator includes a directional coupling unit that multiplexes, on a carrier light beam, a signal light beam of a modulation signal that a carrier signal at a characteristic frequency is modulated with an information signal. The all-optical modulator includes a nonlinear medium that cross-phase-modulates the carrier light beam with the multiplexed signal light beam, and frequency-multiplexes the information signal in the signal light beam on the carrier light beam to generate an optical frequency division multiplexed signal. The all-optical modulator includes a monitoring control unit that controls a polarization control unit that controls a polarization state of the signal light beam in a direction in which an intensity of a modulation component takes a maximum value, based on the intensity of the modulation component involved in a modulation signal at a desired characteristic frequency of the optical frequency division multiplexed signal.

Abstract: In order to reduce the circuit size for a chromatic dispersion pre-equalization operation, an optical multilevel signal pre-equalization circuit is provided with: (1) a plurality of look-up tables in which a string of middle codes utilizing a symmetry of a signal constellation of a multilevel code or a string of middle codes represented by polar coordinates is stored in association with a waveform response component; and (2) one or more operation circuits to which the waveform response component corresponding to a multilevel signal to be transmitted is inputted from the plurality of look-up tables, and which outputs a pre-equalized output waveform corresponding to the multilevel signal by operating the waveform response components outputted from different look-up tables.

Abstract: Arrangement for transmitting an optical digital WDM signal over an optical transmission link or a passive optical network, the signal (SWDM) including N optical channels matching a given optical frequency grid. The scheme includes supplying the WDM signal (SWDM) to a near end of the optical transmission link or a near end of the passive optical network; receiving the WDM signal (SWDM) at a far end of the optical transmission link or at one or more far ends of the passive optical network; separating the optical channel signals (si(t)) by splitting and bandpass filtering the WDM signal (SWDM) received; and converting the optical channel signals (si(t)) into electrical channel signals using direct optical detection. The signal (SWDM) is created such that neighboring channel signals (si(t)) are orthogonally polarized and are conditioned with specific pre-distortion.

Abstract: In general, a wavelength division multiplexed (WDM) communication system may use wavelength selective switching to simultaneously pre-filter and combine groups of channel wavelengths with orthogonal polarizations to provide a pre-filtered, pair-wise orthogonal aggregate WDM optical signal. An orthogonally-combining wavelength selective switch (WSS) multiplexer may route channel wavelengths individually from different sets of channels to a common output. The orthogonally-combining WSS multiplexer may also provide substantially orthogonal polarizations for the wavelengths in the different sets of channels. The different sets of channels may include odd channels and even channels.

Abstract: An optical signal transmitter includes: first outer modulator to generate first modulated optical signal, the first outer modulator including a pair of optical paths and a first phase shifter to give phase difference to the pair of optical paths; second outer modulator to generate second modulated optical signal, the second outer modulator including a pair of optical paths and a second phase shifter to give phase difference to the pair of optical paths; combiner to generate polarization multiplexed optical signal by combining the first and second modulated optical signals; phase controller to control the phase difference by the first phase shifter to A??? and control the phase difference by the second phase shifter to A+??; and power controller to control at least one of the first and second outer modulators based on AC component of the polarization multiplexed optical signal.