2269 results about "Polarization controller" patented technology

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. Based on the intensity output from the filter, a controlling circuit generates feedback control signals for maximizing a ratio of the components of the low-frequency signals and by using the feedback control signals, the polarization controller controls the polarization states of the optical multiplexing signals.

The scanning speed of a sample in Doppler OCT, etc., is increased to enable quick measurement of blood flow rate, blood flow volume, etc. Wideband light from a light source 2 is linearly polarized by a polarization controller 3 and this linearly polarized beam is split into vertically polarized light and horizontally polarized light using a Wollaston prism 14 at a sample arm, which are then irradiated simultaneously onto two different locations of the sample in the scanning direction using a galvanometer mirror18, and reference light from a reference arm 5 and object light from a sample arm 6 are merged and caused to interfere with each other, with the resulting interference signal light passed through a diffraction grating 26 for spectroscopy, while the horizontal component and vertical component are separated by a polarized beam splitter 28, to simultaneously measure the components with two polarization-sensitive optical detectors 29, 30 and thereby obtain two tomography images of the same location at different times by one mechanical scan, thus allowing the amount of temporal change in phase to be measured using the two tomography images.

The invention discloses a continuous variable quantum key distribution system and a synchronous realization method thereof. The continuous quantum key distribution system consists of a light path part and a circuit control part, wherein the light path part mainly consists of a laser, an attenuator, a beam splitter, a polarization controller, am amplitude controller, a phase controller and a coupler. A control part is a transmission end controller module and consists of a true random key generator, an analog voltage output and a trigger clock output. The synchronous method comprises a bit synchronizing step and a frame synchronizing step. The invention provides a completely novel synchronous realization scheme based on properties of continuous variable quantum in an optical fiber, the practical orientation of the continuous variable quantum key distribution system is promoted, and the interference that the continuous variable quantum on the synchronous realization in the optical communication process also can be effectively overcome.

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.

A multi-wireless access technology based over-the-air test system, used for evaluating over-the-air index of a wireless terminal device, has the principle of putting a device to be tested in a three-dimensional space, and establishing a communication link with a base station simulator (namely wireless communications test set); controlling Phi, Theta axles (two axles perpendicular to each other) to rotate according to set step, performing measurement on various angle positions; measuring spherical effective Total Radiated Power of a moving station in the three-dimensional space and Total Isotropic Sensitivity of a receiver. The system mainly comprises a darkroom, a high-accuracy positioning system and its controller(including a rotating axle controller and a polarization controller), a radio frequency test instrument and a main control terminal computer with automatic test program, wherein the radio frequency instruments comprises a wireless communications test set, a spectrum analyzer, a network analyzer and a radio frequency unit.

The invention provides a photon method and system for realizing microwave down-conversion and phase shift by using integrated devices, and belongs to the field of microwave photonics. Firstly, opticalcarriers generated by a laser are input to a double-parallel Mach-Zehnder modulator after passing through a polarization controller, a radio frequency signal is modulated by an upper arm sub-modulator, and carrier suppression double-sideband modulation is realized by DC bias; a local oscillator signal is modulated by a lower arm sub-modulator, and the carrier suppression double-sideband modulation is realized by the DC bias; the DC bias of a main intensity modulator is used for changing the phase difference between the radio frequency optical signal and the local oscillator optical signal. A-1 order optical sideband is filtered from an output carrier suppression double-sideband modulation optical signal by an optical bandpass filter, a +1 order optical sideband is retained, and the useless optical sideband is suppressed below the noise floor. Then, power amplification is performed on the optical signal to compensate the insertion loss of modulator and the filter. At last, a down-conversion signal subjected to phase shift is obtained by performing beat frequency by using a photodetector. A very pure frequency spectrum signal is output, and the performance of an integrated functionlink of down-conversion and phase shift is improved.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening / compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the laser gain medium further amplifying and compacting a laser pulse. The gain medium further includes a Ytterbium doped fiber for amplifying and compacting a laser pulse. The fiber laser cavity further includes a polarization sensitive isolator and a polarization controller for further shaping the output laser.

The polarization direction of a signal is rotated by a polarization controller so as to be orthogonal to the main axis of a polarizer. A control pulse generator generates control pulses from control source with a wavelength which is different from the wavelength of the signal. The signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the signal, during the time period in which the signal and the control pulse coincide, has its polarization direction rotated by cross phase modulation, and is amplified by optical parametric amplification. The signal, during the time period in which the signal and the control pulse coincide, passes through the polarizer.

The invention discloses a frequency octupling millimeter wave generation device by means of a double polarization-quadrature phase shift keying (DP-QPSK) modulator and a method thereof, relates to the technical fields of microwave and optical communication, and is mainly applied to generation of high-frequency millimeter wave. According to the method shown in the appended drawings, the device comprises a light source, a radio frequency signal source, the DP-QPSK modulator, a phase shifter, a power divider, a polarization controller, a polarizer and a photoelectric detector. The nonlinear characteristics and the interference superposition characteristics of the two sub-modulators X-QPSK and Y-QPSK of the DP-QPSK modulator are utilized, and polarization controller is properly adjusted when the two sub-modulators XI and XQ of X-QPSK and a main modulator work at the maximum point so that frequency octupling millimeter wave signals can be generated, the radio frequency index required by generation of high-frequency / extremely-high-frequency signals can be greatly reduced and thus system cost can be reduced. Use of a filter is avoided by the method, and frequency adjustment performance is great. Meanwhile, the generated signals are great in phase noise and frequency spectrum purity.

The invention discloses a microwave photon phase shifter based on a dual-polarization modulator and relates to the technical fields of microwaves and optical communication. The microwave photon phase shifter is mainly applied to microwave photon signal processing. The microwave photon phase shifter is shown in attached drawings and comprises a tunable laser source, a radio frequency signal source, a dual-polarization modulator, an optical band pass filter, a polarization controller, a polarizer and a photoelectric detector. The dual-polarization modulator is composed of Y branching units, upper and lower parallel Mach-Zehnder modulators MZM1 and MZM2 and a polarization beam combiner. According to the scheme, single side band modulation is achieved by utilizing the dual-polarization modulator and the optical band pass filter, the phase difference between optical carrier waves and side bands is changed by combining with the polarization controller and the polarizer, and accordingly dephased microwave signals are obtained after frequency beating of the photoelectric detector. 360-degree continuous phase shift of the microwave signals can be achieved, and the amplitude can be kept unchanged. In addition, the microwave photon phase shifter has the advantages of being simple in structure, easy to operate, wide in band width and the like.

The invention relates to a method and a system for transmitting and receiving by orthogonally dual-polarized differential quaternary phase shift keying. The system comprises a transmitting device and a receiving device, wherein the transmitting device comprises a continuous laser; the continuous laser is connected with a polarization beam splitter which is connected with a DQPSK modulator; the DQPSK modulator is connected with a precoder of which the output end is connected with a tunable optical attenuator or a polarization controller; and the polarization controller is connected with a polarization beam combiner; and the receiving device comprises a DQPSK demodulator, and the DQPSK demodulator is connected with a balanced detector which is connected with a decision circuit. In the method, four paths of electrical signals can be multiplexed, and only one demodulator and two balanced detectors are used at a receiving end to demodulate two orthogonally polarized DQPSK signals at the same time; therefore, compared with D8PSK and x-QAM systems, the system has the advantages of greatly reducing the complexity and remarkably enhancing the stability of components.

The invention discloses a control system of bias voltage of an IQ optical modulator and a control method of the bias voltage of the IQ optical modulator. The control system comprises a laser optical source, a polarization controller, the IQ optical modulator, an optical coupler, a photoelectric detector and a data processing module, which are connected in sequence, wherein the output of the IP optical modulator is divided by the optical coupler, and then is connected to the photoelectric detector; the output of the IP optical modulator is connected with the input of the data processing module; three outputs of the data processing module are respectively sent to the direct current bias voltage input ports of three subsidiary modulators of the IQ optical modulator. The control method comprises the steps of optimizing the bias voltage of a subsidiary phase modulator by measuring the maximum value and the adjacent minimum value of an output optical power, loading the minimum value of search optical power of a path of low-frequency square signal onto two subsidiary intensity modulators in sequence to optimize the bias voltages of the two subsidiary intensity modulators on that basis, and finally realizing the control and locking on each subsidiary modulator working point of the IQ optical modulator. By applying the control system and the control method, the perfect bias point of the IQ optical modulator can be rapidly and automatically controlled.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening / compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the wherein said laser gain medium further comprising a double cladding Ytterbium-doped Photonics crystal fiber (DC YDPCF) for amplifying and compacting a laser pulse. The fiber laser cavity further includes a polarization sensitive isolator and a polarization controller for further shaping the output laser.

A method of using chaos laser to measure distance based on semiconductor laser includes modulating output character of semiconductor laser to make it emit chaos laser signal then splitting chaos laser signal to be reference light and detection light, using detection light to illuminate object to be measured carrying out correlative comparison of scattered back chaos detection light with chaos reference light, applying cross correlation manner to measure round - trip time of chaos detection light. The device for realizing said method is also disclosed.

The present invention discloses a polarization relevant output multi-wavelength and passive mode-locking optical fiber laser which belongs to laser and light communication field. A ring laser cavity includes Er-doped fiber that is taken as gain medium; a 980nm / 1550nm wavelength-division multiplexer is used to couple pumping laser of 980nm into the Er-doped fiber; a polarization relevant isolator with tail optical fiber on two ends guaranties the laser work in one way, meanwhile plays the role of a polarizer; two polarization controllers respectively on two side of the polarization relevant isolator are used to control polarization state, a 10dB coupler with 10% of the terminal port used to output optical signal and 90% of the optical signal stays in the cavity for cycle. A segment of long single mode fiber is inserted in the laser cavity and used to increase nonlinear effect inside the laser cavity; a piece of polarization maintaining optical fiber and a polarization relevant isolator constitute a birefraction optical fiber periodicity filter; the optical fiber laser is provided with two different output modes, namely mode locking pulse output and multi- wavelength continuous wave output, and can adjust polarization and switch between the two output modes.

The embodiment of the invention relates to the field of communication transmission, and discloses an optical signal transmission processing method, an optical signal sending device and an optical signal transmission system. The optical signal sending device comprises a sending end optical signal generating device, a first polarization controller, a second polarized controller, a first quarternaryphase-shift keying modulator, a second quarternary phase-shift keying modulator and a polarization beam combiner, wherein the sending end optical signal generating device is used for generating an optical signal A and an optical signal B with different wavelengths; the first polarization controller is used for carrying out polarization control for the optical signal A and generating an X polarization optical signal A; the second polarized controller is used for carrying out polarization control for the optical signal B and generating a Y polarization optical signal B; the first quarternary phase-shift keying modulator is used for modulating the X polarization optical signal A; the second quarternary phase-shift keying modulator is used for modulating the Y polarization optical signal B; and the polarization beam combiner is used for combining the modulated X polarization optical signal A and the modulated Y polarization optical signal B into a dual-carrier single-polarization optical signal. The invention enables the nonlinear effect in an optical fiber to be inhabited, enhances the nonlinear tolerance limit and the fiber feeding power of the optical signal transmission system andextends the transmission distance.

The invention discloses an ultra-high-precision freezing detecting device and a real-time freezing thickness detecting method thereof. The ultra-high-precision freezing detecting device comprises a wideband light source, a spectrum analyzer, an optical fiber coupler, a film-coated optical fiber, an optical fiber polarization controller, an optical switch and optical fiber probes. The wideband light source and the spectrum analyzer are connected to a port a and a port b which are located on the same side of the optical fiber coupler through optical fibers respectively. The film-coated optical fiber is installed on the optical fiber polarization controller and connected to a port c located on the other side of the optical fiber coupler. The input end of the optical switch is connected to a port d of the optical fiber coupler and the output end of the optical switch is connected with the optical fiber probes. The ultra-high-precision freezing detecting device can realize ultra-high-precision detection of a micrometer-level-thickness ice layer on the surface of an object and accurately forecast the freezing rate. In addition, the device is high in integration degree, low in cost, capable of realizing distributed real-time detection, particularly suitable for airplane freezing detection, capable of realizing safety early warning and capable of being widely applied to other fields in need of freezing condition detection or monitoring.

The invention discloses a loss testing apparatus for a multi-channel optical device, which comprises an optical source module used for supplying laser of various wavelengths and stable power, an optical amplifying module used for amplifying an optical source for a return loss test and equally dividing the optical source into a plurality of channels, an optical power detecting module used for measuring the optical power and the return loss of an output end of the optical device to be measured, a polarization controller used for changing the polarization state of an input optical source, an optical source monitoring module used for detecting the stability of the optical source and testing the return loss of a public end of the device, an optical switch used for selecting one output in the laser of various wavelengths, a single chip computer and a communication module used for controlling a switching channel of the optical switch, wherein the polarization controller is used for changing the polarization state of the laser, receiving the data measured by the optical power detecting module and the optical source monitoring module and processing the data. By adopting the loss testing apparatus provided by the invention, the testing efficiency of various indexes for the multi-channel optical device can be increased to large extent.

The invention relates to a single-photon polarization self-calibrating and locking method and device based on a phase encoding quantum key distribution (QKD) system and a single-photon polarization control based on phase encoding quantum key distribution system. The polarization control scheme is divided into a calibration process and a locking process which are automatically switched through judging the threshold of a feedback signal. According to the scheme, efficient automatic polarization calibration and locking are realized through the matching of a polarization beam splitter, a multi-degree-of-freedom polarization controller and a genetic algorithm; a polarization feedback circuit device comprises the polarization beam splitter, a polarization controller, a single-photon detector, a signal acquiring and processing module and corresponding control circuits. By using the polarization control method, polarization can be continuously and precisely controlled without reset operation in real time under the condition that the strength of the feedback signal is in the single-photon magnitude, and human intervention is not needed in the whole control process.

The invention discloses a wavelength-encoding optical time domain reflection test device and a measurement method thereof. The device comprises an optical wavelength encoding generator, an optical fiber splitting device, a polarization controller, an optical fiber coupler, a photoelectric detector and a beat frequency signal detection device; wherein an encoding optical pulse signal generated from the optical wavelength encoding generator is input from a first port of the optical fiber splitting device and divided into a detection light signal and a reference light signal which are respectively output from a second port and a third port of the optical fiber splitting device; the detection light source enters into an optical fiber link to be tested, and a reflected light signal generated after meeting breakpoints or damages of the optical fiber link to be tested returns to the optical fiber splitting device from the second port and is output from a fourth port; the reflected light signal passes through the polarization controller, then passes through the optical fiber coupler together with the reference light signal and enters into the photoelectric detector to carry out frequency beating, and a beat-frequency low-frequency signal enters into the beat-frequency signal detection device and is then observed and recorded. The invention solves the problems that the OTDR resolution ratio and the dynamic range of the traditional device can not be simultaneously improved.

The invention discloses a sensing signal detecting device and a sensing signal detecting method based on a fiber Brillouin ring laser. The device comprises a narrow linewidth DFB (distributed feedback) laser, three optical fiber couplers, a pulse modulator, two erbium-doped fiber amplifiers, two optical fiber circulators, two single-mode fibers, an optical isolator, a polarization controller and a photoelectric detector, wherein the fiber Brillouin ring laser is composed of the second optical fiber circulator, the second single mode fiber, the optical isolator, the second optical fiber coupler and the polarization controller. Light emitted from the laser is divided into two beams of light via the optical fiber couplers, wherein the probe light is modulated into pulsed light which enters into sensing optical fiber after passing through the erbium-doped fiber amplifiers to ensure that back spontaneous Brillouin scattered signals are generated; the reference light passes through the center frequency of the fiber Brillouin ring laser to ensure that a Brillouin frequency shift is generated; and the coherent detection is carried out on the two Brillouin scattered signals which are scattered back to ensure that the advantages of rapid high-accuracy detection and simple structure are realized by utilizing low-cost devices.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening / compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape. The fiber laser cavity further includes a polarization controller controlled and driven by an electronically tunable driver tapping a small portion of an output laser of the fiber laser cavity to process and filtering the small portion of the output laser to drive the polarization controller to adjust a polarization state of a laser transmission in the laser system whereby the laser cavity is an electronically-tuned self-starting polarization-shaping mode-locked fiber laser.

A transmission unit comprises an optical pulse train generation unit, first channel encoded optical pulse signal generation unit, second channel encoded optical pulse signal generation unit, third channel encoded optical pulse signal generation unit, and fourth channel encoded optical pulse signal generation unit; the second and fourth channels further comprise polarization controllers respectively. By means of these polarization controllers, a polarization control step is executed in which the planes of polarization of first encoded optical pulse signals of the second and fourth channels are rotated by 90°. By executing the polarization control step, the directions of the planes of polarization of the first decoded optical pulse signals of adjacent channels in the reception unit can be caused to be mutually orthogonal.

The invention discloses a microwave photon mixing method and system based on local oscillator frequency doubling, and belongs to the fields of optical communication and microwave photonics. The microwave photon mixing system based on local oscillator frequency doubling is formed by utilizing a double-polarization double-parallel mach-zehnder modulator through combination with devices such as a laser, a front polarization controller, a microwave 90-degree coupler, a rear polarization controller, an optical fiber polarizer, an adjustable optical band-pass filter, an erbium-doped fiber amplifier,a photoelectric detector and the like. The system adopts second-order local oscillator sideband and first-order radio frequency sideband beat frequencies, and mixing processing based on local oscillator frequency doubling can be realized; on one hand, the frequency requirement of a mixing system on a local oscillator signal is reduced, and on the other hand, due to the fact that a single-sidebandmodulation mode is adopted, stray signals can be effectively reduced. In addition, the mixing method can realize switching of up conversion and down conversion by changing a direct current bias voltage, and can be used for time-sharing transmitting and receiving of radio frequency.

A tunable-frequency photoelectric oscillation device based on a wide spectrum light source comprises the wide spectrum light source, an optical filter, a first light amplifier, a second light amplifier, a first optical fiber coupler, a second optical fiber coupler, a third optical fiber coupler, a first polarization controller, a second polarization controller, a dimming-adjustable delay line, an photoelectric modulator, a color-dispersion optical fiber, a first photoelectric detector, a second photoelectric detector, a microwave amplifier, a first optical fiber patch cord, a second optical fiber patch cord, a third optical fiber patch cord, a fourth optical fiber patch cord, a fifth optical fiber patch cord, a sixth optical fiber patch cord, a seventh optical fiber patch cord, a first cable and a second cable. The tunable-frequency photoelectric oscillation device based on the wide spectrum light source can generate wideband-adjustable microwave signals, adopts a microwave photon filter to replace a traditional point filter, overcomes the defect that a traditional photoelectric oscillator based on wide spectrum source cutting can not generate signals at certain frequency points, and has the advantages of being low in cost, adjustable in wideband, and low in phase noise.

A wavelength converter which employs an optical fiber and has high converter efficiency. The polarization planes of a signal light and an exciting light outputted from a laser diode (LD) (103) are respectively controlled by polarization controllers (PC's) (101 and 104) and the phases of the lights are respectively modulated by phase modulators (PM's) (102 and 105) in accordance with modulation signals outputted form an oscillator (110). Then, the output lights form the PM's (102 and 105) are multiplexed by a coupler (106). After the multiplexed signal light and exciting light are amplified by an optical amplifier (EDFA) (107), they are imputed to a dispersion shift fiber (DSP) (108). After wavelength transformation (four light waves mixing (FWM) is practiced in the DSP, and FWM light is outputted through a band-pass filter (BPF) (109).

The invention belongs to the technical field of photoelectric equipments, in particular to a device capable of generating various optical solitons. The optical soliton generation device based on a passive mode-locked ytterbium-doped fiber laser comprises a polarization controller (1), a 1*N optical switch (2), an optical fiber group (3), a 1*N optical coupler (4), a dispersion compensation fiber (5), an optical isolator (6), a ytterbium-doped fiber, a light wavelength division multiplexing (8), a pump light source (9), a saturable absorber (10) and a 1*2 optical coupler (1). In the same passive mode-locked ytterbium-doped fiber laser system, the optical soliton generation device based on the passive mode-locked ytterbium-doped fiber laser is capable of obtaining parabolic dissipative soliton single-pulse optical solitons, hyperbolic secant-shaped soliton single-pulse optical solitons, bounded multi-soliton optical solitons of the two optical pulses and other optical solitons; when switching between different types of solitons, a user does not need to change a light path structure, and the switching speed is very fast.

An optical signal processing device has nonlinear optical medium, first and second power controllers, and polarization controllers. To the nonlinear optical medium, signal light, and first and second pumping lights having wavelengths different from the signal light are input. The first and the second power controllers are provided at the input side of the nonlinear optical medium, and control the powers of the first and the second pumping lights so that a predetermined gain is obtained in the nonlinear optical medium. The polarization controllers are provided at the input side of the nonlinear optical medium, and adjust the first and the second pumping lights so that the polarization states of the first and the second pumping lights are mutually orthogonal.

The invention discloses a tunable microwave photon filter on the basis of a Brillouin optical fiber laser, which belongs to the filed of microwave photonics. The device consists of a Brillouin multiple-wavelength optical fiber laser, a polarization controller, a Mach-Zehnder modulator, a monomode optical fiber and a photoelectric detector. A multiple-wavelength optical signal output by the Brillouin multiple-wavelength optical fiber laser is connected with the optical input end of the Mach-Zehnder modulator through the polarization controller; the radio frequency input end of the Mach-Zehnder modulator loads a radio frequency signal; the optical output end of the Mach-Zehnder modulator is connected with the monomode optical fiber; the other end of the monomode optical fiber is coupled into the photoelectric detector; and a signal acquired by the output end of the photoelectric detector is a microwave filtering signal. Through tuning the wavelength of output laser of the Brillouin optical fiber laser, the tuning of the microwave filtering frequency can be realized.