59 results about "Delay line interferometer" patented technology

The invention proposes a method for feedback control, in which a portion of a data signal is split and rectified and the signal intensity is detected with slow speed electronics for improving the control of a delay line interferometer (DLI) used in optical data transmission. A control signal is generated and fed back to the DLI based on the detected signal intensity. The invention further proposes a device provided with a DLI, a first and second optoelectronic component, and a differential amplifier.

An optical receiver apparatus and methods for mitigating intersymbol interference (ISI) in a differentially-encoded modulation transmission system by controlling constructive and destructive transfer functions. The receiver includes a bandwidth control element for controlling transfer function bandwidth, a transfer phase controller for controlling transfer function phase and/or an imbalancer for imbalancing the transfer functions for compensating for intersymbol interference and optimizing the quality of the received optical signal.

A DPSK demodulator is implemented in Sagnac interferometer configuration with a delay line element introduced in one or both of the optical paths of the transmitted and reflected beams. Because the two reflected and transmitted beams travel on the same optical path (though in opposite directions), the Sagnac interferometer provides all the advantages of a common-path interferometer, is thermally and mechanically stable, and the phase requirements are greatly reduced. In its simplest form, the Sagnac DPSK demodulator. In the preferred embodiment, the beam-splitting surface and one of the mirrors are combined into a rhomb beam-splitter structure and the other two mirrors into a right-angle prism. In a DQPSK embodiment, the input beam is split by an upfront beam splitter into two parallel beams that are then directed toward the rhomb-beam-splitter/right-angle-prism combination of the invention.

Method and devices of controlling wavelengths in two-channel DEMUX/MUX in silicon photonics are provided. The two-channel DEMUX/MUX includes a waveguide-based delay-line-interferometer at least in receiver portion of a two-channel transceiver for DWDM optical transmission loop and is configured to split a light wave with combined two-wavelengths into one light wave with locked one channel wavelength and another light wave with locked another channel wavelength. The waveguide-based delayed-line interferometer (DLI) is characterized by a free-spectral-range configured to be equal to twice of channel spacing. The method includes tuning heater of DLI in receiver of each two-channel transceiver by using either low-frequency dither signals added on MZMs associated with respective two channels as feedback signal or one DFB laser wavelength tapped from an input of transmitter portion at one channel before or after the MZMs as a direct wavelength reference to feed into an output of receiver portion at another channel.

In a delay line interferometer inside a demodulator, with respect to polarization states of two split beams of light to be interfered with each other, p polarization and s polarization are reversed by a half beam splitter and, further, again multiplexed by the half beam splitter used for splitting so that interference beams of light are generated.

An all-optical modulation format converter for converting optical data signals modulated in an on-off-keying (OOK) format to a phase-shift-keying (PSK) format. The OOK-to-PSK converter can be coupled to a delay-line interferometer to provide an all-optical wavelength converter for differential PSK (DPSK). The OOK-to-PSK converter can also be used in all-optical implementations of various functions, including, for example, exclusive-OR (XOR) logic, shift registers, and pseudo-random binary sequence (PRBS) generators.

The invention relates to a monolithically integrated multi-wavelength differential quadrature phase shift keying (DQPSK) demodulator and a manufacturing method thereof. The demodulator is provided with a 1*D wavelength division demultiplexer and D DQPSK demodulators which are integrated on the same waveguide substrate to form a waveguide structure chip. The method comprises the following steps of: monolithically integrating the wavelength division demultiplexer AWG and a plurality of multi-wavelength optical DQPSK demodulators with delay line interferometers on the same waveguide substrate by planar optical waveguide technology to manufacture the waveguide structure chip; manufacturing a metal film micro-heater on one of two arms of each optical delay line interferometer forming the DQPSK demodulator by a photoetching, sputtering and stripping semiconductor process to realize phase control; adhering a thermoelectric cooler (TEC) to a chip substrate to control the temperature of the whole chip; and respectively connecting the metal film micro-heater and the TEC with an error signal from a control feedback loop. The DQPSK demodulator has low cost, the process is simple and the method contributes to mass production.

The invention provides an optical transmitter with a hybrid modulation format. The optical transmitter is applied to a passive optical access network and a long-distance optical transmission system, wherein the passive optical access network is formed by integrating a wavelength division multiplexer and an optical branching device. The optical transmitter comprises an I/Q modulator 1, an I/Q modulator 2, a delay line interferometer and a Mach-Zehnder modulator. The I/Q modulator 1 is in cascade connection with the delay line interferometer, then is in cascade connection with the I/Q modulator 2 and lastly, is in cascade connection with the Mach-Zehnder modulator. The two I/Q modulators are respectively provided with two data input ports, and the Mach-Zehnder modulator is provided with one data input port. The optical transmitter is controlled to output an optical signal with the self-adaptation hybrid modulation format by controlling the on-off and the signal amplitude of the data input ports and the bit and the phase position delay of the delay line interferometer. By means of the optical transmitter, QPSK modulation, 8 QAM modulation and circular 16 QAM modulation can be achieved, and hybrid transmission formed by various modulation formats in any proportional mode can also be achieved. The optical transmitter can be applied to complex transmission links under the wavelength division multiplexing passive optical network environment, and the frequency spectrum utilization efficiency can be effectively improved.

A two-channel DWDM spectral combiner integrated with a wavelength locker is provided. Two optical signals at ITU grid channels are separately modulated by MZM modulators and combined into a silicon waveguide-based delayed-line interferometer built on silicon-on-insulator substrate to produce a combined signal having a free spectral range equal to twice of the spacing of the two ITU grid channels. Two dither signals can be added respectively to the two optical signals for identifying corresponding two channel wavelengths and locking each wavelength while outputting the combined signal.

A frequency stabilizer includes: a delay line interferometer that receives an optical signal corresponding to one frequency mode of a pulsed laser, divides and transmits the received optical signal to a reference arm and a delay arm including an optical fiber delay line, and then outputs an interference signal between signals passing through the reference arm and the delay arm; a photoelectric converter that converts the interference signal into an electrical signal; a mixer that generates a baseband signal of the electrical signal by mixing a carrier frequency signal; and a feedback controller that transmits a control signal generated based on the baseband signal to the pulsed laser. The optical signal passing through the delay arm is weighted with a delay time caused by the optical fiber delay line compared to the optical signal passing through the reference arm, and the optical signal passing through the delay arm is frequency shifted to a carrier frequency of an oscillator. A carrier-envelope offset frequency of the pulsed laser is stabilized by an offset frequency stabilizer.

The invention relates to a fast self-adaptive dispersion compensation method in a 40Gbps DWDM (dense wavelength division multiplexing) system. The fast self-adaptive dispersion compensation method specifically comprises the following steps: step A) delaying coarse regulation of an interferometer DLI (delay line interferometer) by an OTU (optical transport unit) receiver; step B) performing dispersion coarse regulation through a dichotomic method; step C) performing fine regulation through a TDC (time-to-digital converter); step D): optimizing the DLI through the receiver; and step E) monitoring through the TDC, judging whether dispersion changes or not by FEC (forward error control) error correction counting or warning and entering step B) or C) if the dispersion changes. According to the method disclosed by the invention, a coarse regulation point is fast found by using the dichotomic method, the optimal dispersion is found by adopting a mid-point method after entering the fine regulation step, the dispersion compensation time is effectively reduced, the efficiency is improved, and the defects of local optimization can be simultaneously avoided.

An apparatus of polarization self-compensated delay line interferometer. The apparatus includes a first waveguide arm of a first material of a first length disposed between an input coupler and an output coupler and a second waveguide arm of the first material of a second length different from the first length disposed between the same input coupler and the same output coupler. The apparatus produces an interference spectrum with multiple periodic passband peaks where certain TE (transverse electric) and TM (transverse magnetic) polarization mode passband peaks are lined up. The apparatus further includes a section of waveguide of a birefringence material of a third length added to the second waveguide arm to induce a phase shift of the lined-up TE/TM passband peaks to a designated grid as corresponding polarization compensated channels of a wide optical band.

An interferometer includes a means for splitting, at a splitting location, an input light beam into a first beam and a second beam; and means for recombining, at a recombination location, the first beam and the second beam. The interferometer is designed such that the first beam will travel a first optical path length (OPL) from the splitting location to the recombination location, and the second beam will travel a second OPL from the splitting location to the recombination location and such that when the input light beam has been modulated at a data rate comprising a time interval, then the difference in optical path lengths between the first OPL and the second OPL is about equal to the time interval multiplied by the speed of light

A switchable free-spectral-range mode selector is used to change the free spectral range of a free-space delay-line interferometer. The mode selector consists of a rotatable device with at least one transparent plate selected to produce the desired change in the free spectral range of the delay-line interferometer. The device may be rotated in and out of the free-space optical path of on of the interferometer arms. If used as a DPSK demodulator, the device enables operation at multiple predetermined free spectral ranges. In the preferred embodiment, the demodulator includes a 50/50 beam-splitter cube combined with two cavities. The mode selector consists of a plurality of different transparent slabs attached to a rotatable shaft so that any one of the slabs or none may be inserted in the appropriate optical path to obtain the desired FSR mode of operation.

The invention discloses an LLO-based single-wavelength quantum and classic communication simultaneous transmission method. A multi-user Alice terminal, a multiplexing module and a multi-user Bob terminal are included, and the multi-user Alice terminal, the multiplexing module and the multi-user Bob terminal are connected in sequence through optical fibers. Quantum signals and classic signals are coded on the same weak coherent pulse by adopting a single-wavelength multiplexing method, so that additional requirements of QKD for hardware equipment are reduced, and the practicability of the QKD technology is improved. The LLO scheme is adopted to close security vulnerabilities brought by an eavesdropper by manipulating the LO on the common channel, and the LLO is realized by adopting the unbalanced delay line interferometer, so that the system can tolerate stronger phase noise. Wavelength division multiplexing is combined with single-wavelength multiplexing, the system capacity of the system is further improved, and a realistic way is opened up for developing a coherent quantum and classical fusion system compatible with a next-generation network.