Abstract: Polarization multiplexing by encoding data using a return-to-zero format, and by interleaving the constituent orthogonal polarization components such that the data-carrying portion of the bit window from one orthogonal polarization component occupies the zero portion of the bit window for the other orthogonal polarization component.

Abstract: A method of stabilizing the state of polarization of an optical radiation comprises: 1) applying sequentially to the optical radiation a first and a second controllable phase retardation; 2) detecting an optical power of at least a first polarized portion of the optical radiation obtained after step 1; 3) applying sequentially to the optical radiation obtained after step 1 a third and a fourth controllable phase retardation; 4) detecting an optical power of a further polarized portion of the optical radiation obtained after step 3; 5) controlling, responsive to the optical power of said first polarized portion, the second controllable phase retardation so as to maintain the polarization state of the optical radiation obtained after step 1 at a defined great circle r on a Poincare sphere; 6) in case the second controllable phase retardation reaches a first limit value, commuting the first controllable phase retardation between first and second values; 7) controlling, responsive to the optical power of said fur

Abstract: The polarization direction of an optical signal is changed by a polarization controller so as to be orthogonal to a main axis of a polarizer. A control pulse generator generates control pulses from control beam with a wavelength which is different from the wavelength of the optical signal. The optical signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the optical signal, during a time period in which the optical signal and the control pulse coincide, is amplified with optical parametric amplification around a polarization direction of the control pulse. The optical signal, during the time period in which the optical signal and the control pulse coincide, passes through the polarizer.

Abstract: A method for implementing Polarization Division Multiplexing Binary Phase Shift Keying (PDM-BPSK) modulation and Quadrature Phase Shift Keying (QPSK) modulation in a compatible manner includes: dividing a direct current (DC) light into a first channel of light and a second channel of light with the same power; separately performing optoelectrical modulation on the first channel of light and the second channel of light and correspondingly outputting a first optical signal and a second optical signal in a Binary Phase Shift Keying (BPSK) format; performing polarization state control on the first optical signal; performing a phase shift on the first optical signal or the second optical signal; and performing optical signal combination with the polarization state preserved on the first optical signal and the second optical signal after the polarization state control and the phase shift, and outputting a PDM-BPSK modulation optical signal or a QPSK modulation optical signal.

Abstract: An optical reception device (10) includes an electrical signal converter (110) that converts an optical signal serving as an input polarization multiplexed signal into electrical signals of respective polarization components, a signal processor (120) that executes digital signal processing for digital signals generated by executing A/D conversion processing, and a phase difference output unit (130) that detects a phase difference generated between the polarization components of the optical signal based on the signals having undergone digital signal processing, and outputs information representing the phase difference. The signal processor (120) compensates for the distortion of the optical signal based on the information representing the phase difference.

Abstract: Aspects of the invention provide transmitters and receivers for managing multiple optical signals. High order modulation, such as phase and/or amplitude modulation, is used to achieve multiple bits per symbol by transporting multiple asynchronous data streams in an optical transport system. One or more supplemental multiplexing techniques such as time division multiplexing, polarization multiplexing and sub-carrier multiplexing may be used in conjunction with the high order modulation processing. This may be done in various combinations to realize a highly spectrally efficient multi-data stream transport mechanism. The system receives a number of asynchronous signals which are unframed and synchronized, and then reframed and tagged prior to the high order modulation. Differential encoding may also be performed. Upon reception of the multiplexed optical signal, the receiver circuitry may employ either direct detection without a local oscillator or coherent detection with a local oscillator.

Abstract: An optical method for generating an optical quadrature duobinary QDB signal includes receiving a quadrature phase-shift-keying QPSK signal, and adding a delay to the received quadrature phase-shift-keying QPSK signal to generate an optical quadrature duobinary signal.

Abstract: An optical transmission system includes: a two-lightwave generator for generating optical signals having wavelengths ?1 and ?2 from laser light; a photodetector for detecting a microwave signal M12 from two optical signals distributed by an optical coupler; an optical modulator for frequency-shifting the two optical signals; a Faraday reflector for reflecting the two optical signals; an optical coupler for mixing the two optical signals that have been reflected by the Faraday reflector, frequency-shifted again, transmitted by an optical fiber, and guided by a polarization beam splitter, with two optical signals distributed by an optical coupler; an optical demultiplexer for wavelength-dividing four mixed optical signals into optical signals having the wavelengths ?1 and ?2; photodetectors for detecting respective beat signals of the wavelength-divided optical signals having ?1 and ?2; and a phase difference detector for detecting a phase difference between the beat signals of the optical signals having ?1 and

Abstract: Systems and methods are disclosed with a spatial-domain-based multi-dimensional coded-modulation scheme that improves dramatically OSNR sensitivity and tolerance to fiber nonlinearities by using D-dimensional signal constellations, where D=2(2+M)N. The factor 2 originates from two polarizations, 2+M electrical basis functions are selected (2 in-phase/quadrature channels and M pulse-position like basis functions), and N represents the number of orbital angular momentum (OAM) states used in FMFs/MMFs. For single mode fiber applications N is 1.

Abstract: For coherent fiber optic communications, the nonlinear XPolM impairment is the most important issue to realize over-100 Gbps high-speed transmissions. A method provides a way to cancel time-varying XPolM crosstalk by introducing multi-stage adaptive mechanism. In the method, a low-complexity adaptive filtering based on recursive least-squares (RLS) first tracks the time-varying crosstalk along with the per-survivor trellis-state decoding. The estimated channel and the decoded data are then used to calculate the empirical covariance, which is in turn exploited to obtain more accurate channel estimates by means of optimal-weighted least-squares. This is performed with a low-complexity processing over frequency domain with fast Fourier transform. The performance is significantly improved with turbo principle decoding, more specifically, iterative decoding and iterative estimation over a block.

Abstract: An optical communication system includes a polarization multiplexed orthogonal frequency-division multiplexing POLMUX-OFDM transmitter for generating a POLMUX-OFDM double sideband signal, an optical processing path for processing the double sideband signal from the transmitter; an analog-to-digital convert ADC-OFDM receiver coupled to the optical processing path for receiving the double sideband signal processed by the optical path; and a block-diagonal multiple-input multiple-output MIMO equalizer responsive to the receiver for enabling correct operation for a completely random incoming signal polarization state without adaptive polarization control at said receiver, which enables complexity.

Abstract: Systems and methods are disclosed to perform four-dimensional optical multiband OFDM communication by organizing an N-dimensional (ND) signal constellation points as a signal matrix; performing 2D-inverse FFT and 2D-FFT to perform modulation and demodulation, respectively; and applying both orthogonal polarizations in the OFDM communication to deal with chromatic dispersion, PMD and PDL effects, and multidimensional signal constellation to improve optical signal-to-noise ratio (OSNR) sensitivity.

Abstract: Systems and methods are disclosed to provide optical communication by using subcarriers as individual bases functions, obtaining signal constellation points of an N-dimensional pulse amplitude modulation (ND-PAM) constellation diagram as an N-dimensional Cartesian product of a one-dimensional PAM; and transmitting the N-dimensional signal constellation point over all N orthogonal subcarriers serving as individual bases functions.

Abstract: A wavelength converter that operates on an optical signal having single or multiplexed polarizations and which exhibits any modulation format.

Abstract: A method for joint transmitter and receiver processing for computationally efficient equalization in polarization multiplexed (POLMUX) optical orthogonal frequency division multiplexed (OFDM) transmission with direct detection.

Abstract: Method and system for optimally equalizing distortion of an optical data channel carrying coherent optical signals with a given analog bandwidth B. A receiving end with IQ paths receives signals and a balanced detector detects signals in each path. The bandwidth of the detected signals is reduced by a factor of N by filtering the output of each path using an AAF with a cutoff frequency optimized to the analog bandwidth 2B/N of each path, where the AAF has deterministic attributes and introducing Known ISI. The signal is sampled at the AAF output by an ADC, at a sampling rate of 2B/N. The samples of each path are post-processed by a digital processor operating at a data rate of 2B/N, where post-processing represents the compensation of the distortion and the input data stream is reconstructed by optimally decoding the output of the processor using a decoder, which compensates the ISI.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Polarization multiplexing with different differential phase shift keying (DPSK) schemes generally uses DPSK modulated signals modulated using different DPSK modulation schemes and combined with orthogonal polarizations relative to each other. The different DPSK modulation schemes may use different DPSK phase shifts to represent data, such as a regular DPSK modulation scheme and a ?/2 DPSK modulation scheme. By using different DPSK modulation schemes to represent data on the orthogonally polarized signals, the DPSK demodulators may effectively separate the orthogonally polarized signals using the property of the DPSK receivers. To optimize performance, the DPSK modulated signals may also be bit-interleaved when combined with orthogonal polarization.

Abstract: A demodulator includes: a splitter that branches a differential phase shift keying optical signal into a first branched optical signal passing through a first optical path and a second branched optical signal passing through a second optical path; a multiplexer that multiplexes the first branched optical signal having passed through the first optical path and the second branched optical signal having passed through the second optical path and makes interference between the first branched optical signal and the second branched optical signal; and a double refraction medium that reduces difference between phase differences between each polarized wave between the first branched optical signal and the second branched optical signal multiplexed by the multiplexer.

Abstract: In an optical transmission system which utilizes polarization multiplexing, a receiver includes an adaptive equalizer which is adjusted at turn-up such that two polarization modes at the equalizer output are time aligned. The adaptive equalizer may be reset in a directed manner in response to an indication that one polarization mode is present at both the first and second outputs. Further, the dominant filters taps of the adaptive equalizer are maintained near a middle of a tap index range. The receiver may also include an interpolation function upstream of the adaptive equalizer and a symbol timing error estimation function that feeds a control signal back to the interpolation function, wherein the interpolation function causes the adaptive equalizer function and symbol timing error estimation function to receive an integer number of samples per symbol.

Abstract: A system to communicate optical data signals in parallel includes an optical splitter to split the data signals into two polarization multiplexed (PM) signals; and two reception channels coupled to the optical splitter, where each reception channel tracks and isolates a PM signal independently.

Abstract: An apparatus transmits data using a format where information bits intended for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through pulse position modulation (PPM) format and the rest of which are encoded through an additional modulation format on each PPM pulse. The additional modulation format for the PPM pulse may be at least one of a polarization-division-multiplexed (PDM) modulation, phase-shift keying (PSK) modulation, polarization shift keying (PolSK) modulation, amplitude modulation (AM), quadrature-amplitude modulation (QAM) modulation, or a combination thereof. In one embodiment, the additional modulation of the PPM pulses is through polarization-division-multiplexed quadrature-phase-shift keying (PDM-QPSK). The unique combined use of PDM-QPSK and PPM produces much higher receiver sensitivity than either PPM or PDM-QPSK alone.

Abstract: Systems and methods are disclosed for a filter-less coherent receiving system with a filter-less coherent receiver frontend; a signal-signal beat-noise detector coupled to the filter-less coherent receiver frontend; and a real-time processor coupled to the filter-less coherent receiver frontend and the signal-signal beat-noise detector to reject signal-signal interference.

Abstract: Embodiments of the present invention provide systems, devices and methods for managing skew within a polarized multi-channel optical transport system. In a DP-QPSK system, skew between polarized channels is compensated within the transport system by adding latency to at least one of the polarized channels. The amount of added latency may depend on various factors including the skew tolerance of the transport system and the amount of skew across the channels without compensation. This latency may be added optically or electrically, and at various locations on a channel signal path within a transport node, such as a terminal transmitter or receiver. Additionally, various embodiments of the invention provide for novel methods of inserting frame alignment bit sequences within the transport frame overhead so that alignment and skew compensation may be more efficiently and accurately performed at the transport receiver.

Abstract: A method of testing a dual-polarization optical transmitter comprising a pair of polarization transmitters for respectively generating first and second polarization signals, and a polarization combiner for generating an optical signal composed of the first and second polarization signals with respective orthogonal polarization vectors. Each of the polarization transmitters is controlled to transmit respective polarization optical signals having predetermined characteristics. An output of the dual-polarization optical transmitter is tapped to obtain a first tap signal representative of the first polarization signal, and a second tap signal representative of the second polarization signal. A relative angle between respective polarization vectors of the tap signals is controlled, and the first and second tap signals combined to generate a combined light. A power level of the combined light is detected, and processed to obtain information about the performance of the dual polarization transmitter.

Abstract: A polarization multiplexing optical receiver includes a polarization controller configured to control a polarization state of a polarization multiplexed optical signal; a polarization splitter configured to split the polarization multiplexed optical signal for which the polarization state is controlled by the polarization controller into a first polarization signal and a second polarization signal; a first detector configured to detect an optical power of the first polarization signal and output a first optical power signal representing the optical power of the first polarization signal; a second detector configured to detect an optical power of the second polarization signal and output a second optical power signal representing the optical power of the second polarization signal; and a controller configured to control the polarization controller on the basis of the first optical power signal and the second optical power signal.

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

Abstract: A method of transmitting data using electromagnetic waves, comprising the steps of providing (101) a first electromagnetic signal (S1) having a first wavelength (?1) and a second electromagnetic signal (S2) having a second wavelength (?2) different from the first wavelength; dividing (102) each of the first (S1) and second (S2) electromagnetic signals into a first polarization component (S1x; S2x) having a first polarization direction and a second polarization component (S1y; S2y) having a second polarization direction orthogonal to the first polarization direction; modulating (103) the first polarization component (S1x) of the first electromagnetic signal (S1) to encode a first data stream (DS1); modulating (104) the second polarization component (S2y) of the second electromagnetic signal (S2) to encode a second data stream (DS2); and transmitting (105) a combined electromagnetic signal (Scomb) comprising the first and second polarization components of the first electromagnetic signal (S1) and the first and

Abstract: The invention provides a PLC-type DP-QPSK demodulator that reduces connection loss between a polarization beam splitter and a 90-degree hybrid circuit and aims at reducing the manufacturing cost and an optical transmission system using the same. In an embodiment of the invention, a PLC-type DP-QPSK demodulator that receives a DP-QPSK signal includes one PLC chip having a planar lightwave circuit. Input ports and output ports of signal light are provided at an input end and at an output end of the PLC chip, respectively. Within the planar lightwave circuit, there are integrated a polarization beam splitter that splits the DP-QPSK signal into an X-polarization QPSK signal and a Y-polarization QPSK signal, and two 90-degree hybrid circuits that mix the X-polarization QPSK signal and local oscillation light and the Y-polarization QPSK signal and local oscillation light, respectively, split each QPSK signal into orthogonal components I, Q and output them.

Abstract: There are provided a polarized light passing device to pass therethrough specific polarized light, of output light of a polarization scrambler; and a detecting unit to detect a modulation component according to a frequency of a polarization control signal from the light which passes through the polarized light passing device.

Abstract: Apparatus and methods for receiving and processing optical signals carrying symbols that represent data, including an optical receiver having fractional sampling analog-to-digital conversion and interpolation timing recovery synchronization for processing an optical signal.

Abstract: By using low-frequency signals, an optical transmitting unit modulates one of a wavelength, a transmission timing, and an intensity of light as a carrier wave. A polarization multiplexer synthesizes the output light signals, modulated by the optical transmitting unit, in polarization states orthogonal to each other and generates polarization-multiplexing signals. A polarization splitter splits by extracting two orthogonal polarization components from the polarization-multiplexing signals. The polarization states of the polarization-multiplexing signals are controlled by a polarization controller in an optical receiving unit. A band-pass filter extracts components transmitting through passbands from output signals of the optical receiving unit and outputs an intensity of the components.

Abstract: A method and an apparatus for generating a differential quadrature phase shift keying (DQPSK) code optical signal are provided. The method may includes splitting an optical signal to obtain two polarized optical signals, modulating and phase-shifting one of the two polarized optical signals to obtain a phase-shifted and polarized optical signal, and modulating the other of the two polarized optical signals to obtain another polarized and modulated optical signal. The phase-shifted and polarized optical signal may be combined with the other polarized and modulated optical signal to obtain a polarization multiplexed optical signal. The method may further include, polarizing the polarization multiplexed optical signal to obtain the DQPSK code optical signal. The apparatus may include a polarization beam splitter (PBS), modulators, a phase-shift controller, a polarization beam combiner (PBC), and a polarizer.

Abstract: Multi-laser transmitter optical subassemblies (TOSAs) for optoelectronic modules. In one example embodiment, a multi-laser TOSA includes first and second lasers configured to generate first and second optical signals, respectively, a polarization beam combiner (PBC), first and second collimating lenses positioned between the first and second lasers, respectively, and the PBC, a half waveplate positioned between the first laser and the PBC, and a focusing lens. The half waveplate is configured to rotate the polarization of the first optical signal. The PBC is configured to combine the first and second optical signals and transmit the combined first and second optical signals toward the focusing lens.

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: In an optical transmission system including a transmitter Tx and a receiver Rx connected via a fiber link F, where the receiver Rx is adapted to utilize Forward Error Correction (FEC) on received signals, a polarization scrambler is provided at the transmitter Tx to scramble the polarization state of a transmitted signal, a polarization delay line is provided at the receiver Rx for controlling the polarization mode dispersion induced distortion of a received signal, a feedback unit is provided at the receiver Rx for providing a feedback signal based on at least part of the received signal, and at least one polarization controller interconnects the fiber link F and the polarization delay line. The polarization controller is operable based on the feedback signal to mitigate the polarization mode dispersion of the signal.

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: Return To Zero (RZ) shaping is performed for a first I/Q modulator whose output corresponds to a first polarization component using a first two digital-to-analog convertors (DACs), each of which is sampled at approximately twice a modulation symbol rate or more and has an output with a first interleaving order that interleaves one of a first pair of intended drive signal patterns and zeros. RZ shaping is also performed for a second I/Q modulator whose output corresponds to a second polarization component using a second two DACs, each sampled at approximately twice the modulation symbol rate or more and having a second interleaving order that interleaves zeros and one of a second pair of intended drive signal patterns, the second interleaving order opposite the first interleaving order. The first polarization and the second polarization may be combined, thereby forming an Interleaved Return To Zero (IRZ) Polarization Division Multiplexed (PDM) signal.

Abstract: Systems and methods of polarization-time coding are disclosed. One method includes encoding information in orthogonal polarizations of light and correlated information in multiple time slots, and transmitting the information using the orthogonal polarizations in the time slots. Another method includes receiving a first input pair which specifies a first polarization state and a second input pair containing which specifies a second polarization state; transforming each input pair according to a matrix specifying a conjugate operation to produce four output pairs. The method further includes transmitting at a first time the first output pair using the first polarization state and the third output pair using the second polarization state. The method further includes transmitting at a second time the second output pair using the first polarization state and the fourth output pair using the second polarization state.

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: Disclosed is an optical receiver including: a polarization splitter splitting two polarization components perpendicular to each other from an optical signal to output a first polarization signal and a second polarization signal; a first optical delay splitter and a second optical delay splitter branching each polarization signal to output two branch signals, respectively; a first optical hybrid and a second optical hybrid each outputting four interference signals in which a phase shift increases by each 90° by using the two branch signals; and four photo detectors each outputting a differential signal between two interference signals in which the phase shift is 180° .

Abstract: A seed light module for a WDM-PON system is provided. The seed light module includes a reflector configured to reflect a part of seed light that is generated from a light source generator, and an optical attenuator configured to attenuate the intensity of the reflected seed light and provide the attenuated seed light, which corresponds to a signal generated by attenuating the intensity of the reflected seed light, to the light source generator.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: System, apparatus and method of optical communication are provided for performing digital compensation of the self-phase modulation (SPM) effect experienced by a polarization-division multiplexed (PDM) orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission by compensating a complex digital waveform representing one orthogonal polarization component of the optical PDM-OFDM signal based on both digital waveforms representing two orthogonal polarization components of the PDM-OFDM signal. The compensation of the digital waveform may be further based on an anticipated mean total nonlinear phase shift experienced by the signal during fiber transmission due to SPM. The compensation may be divided into pre-compensation at the PDM-OFDM transmitter and post-compensation at the PDM-OFDM receiver.

Abstract: The present disclosure is directed towards the transmission of data and/or power using nanophotonic elements. For example, in one embodiment, a medical imaging system is provided.

Abstract: A device and method for stabilizing the state of polarization of polarization multiplexed optical radiation including an identified channel is disclosed.

Abstract: A dense wavelength-division-multiplexing (DWDM) system, comprising a plurality of laser transmitters, a wavelength division multiplexer (WDM) optically coupled to the laser transmitters and to an output optical transmission media, a coupler optically coupled to the output optical transmission media, an interferometric filter optically coupled to the coupler but not directly to the output optical transmission media, and a light reflector optically coupled to the interferometric filter and not directly to the output optical transmission media.

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: There is provided a method for detecting optical signals comprising employing a photo diode to both directly detect a received optical signal and convert it into an electrical signal for recovery of data bit stream information in the received optical signal, the received optical signal being derived from a separation of two polarization multiplexed optical signals that were combined before being received.

Abstract: An optical transmitting apparatus optically modulates a transmitting signal to transmit the signal to an optical receiving apparatus using a phase of two optical carriers having each wavelength, and an optical receiving apparatus demodulates an optical signal having a modulated phase with intensity modulation to detect a transmitting signal.