116 results about "Nonlinear polarization" patented technology

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 invention discloses an apparatus for measuring the ferroelectric hysteresis of ferroelectric materials which is based on a current measurement circuit, as well as a measurement method thereof. The invention inputs a simulated output signal generated by a computer processing unit into a high voltage amplifier through a signal source and a data acquisition board, thus giving excitation voltage to a sample being tested, and then through a sampling resistance R0, sampled current signal is input into a signal regulating module through an operational amplifier, and then the sampled current signal is transmitted back into the computer processing unit through the data acquisition board. By separating the current signal acquired from the measurement into three parts as linear polarization, non-linear polarization and electric loss, the measurement system is provided with not only the function of measuring the P-E relationship, but also the function of acquiring the relationship between the real spontaneous polarization and induced polarization of the dielectric substance being tested and the field intensity. Furthermore, by superimposing actuating signal of a small alternative electric field to a bias electric field with constant intensity and synchronously collecting the corresponding change information of the polarization intensity of the sample being tested, then the reversible permittivity can be acquired.

The invention relates to a device and a method for testing a nonlinear polarization coefficient and an absorption coefficient at a terahertz band. Laser is split into one path of pump light and one path of probe light by a beam splitter, wherein the probe light is reflected by a reflector group with an adjustable light path, is attenuated by a metal attenuation piece used for adjusting the beam intensity of incident laser and then is reflected to a high resistance silicon chip by the reflector; the pump light split by the beam splitter is reflected to enter a terahertz generation device so as to generate terahertz collimating light and the generated terahertz collimating light is focused on a sample rack at a focus position by a parabolic mirror by virtue of a terahertz polarizing plate, and the terahertz is converted into parallel light which is reflected to the high resistance silicon chip by another parabolic mirror; and the two paths of light are coincided at the high resistance silicon chip, are focused to a detection crystal by the parabolic mirrors, are focused to reach a Wollaston prism by virtue of a 1 / 4 wave plate after being scattered by using a convex lens and are respectively focused to two photoelectric detectors. A test sample only needs to be arranged at the position of the sample rack or the detection crystal in a light path, namely the nonlinear polarization coefficient and the absorption coefficient of the sample at the terahertz band can be tested.

The present invention applies microprocessing technique to utilize high refractive index of semiconductor material to prepare high quality of two-dimensional photon crystal with defect state and optical switch can be realized by utilizing high third order-nonlinear polarizability and quick response time of semiconductor material. The produced optical switch can be widely used in field of optical communication and optical computer.

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.

A polarization type optical buffer together with the adjusting method is designed for the low turning on and off speed and the instability of the avoiding polarization state, namely using the nonlinear rotation of the polarization state in a semiconductor optical amplifier or an optical fiber as a polarization control switch to realize the optical buffer to cache the data packet signal. The optical buffer consists of an input polarization controller, a polarization beam combiner, a nonlinear polarization rotation functional unit, a polarization beam splitter and a polarization maintaining fiber, wherein, the nonlinear polarization rotation functional unit consists of a front polarizer, a tail polarizer, the controllable non-linear rotation functional parts and an online monitoring unit of the polarization state composed by an optical fiber coupler and a polarization controller. The instability of the polarization can be avoided by adjusting the polarization type optical buffer to the polarized rotation. The polarization type optical buffer of the invention has the advantages that the reading and writing speed is high and the buffer depth of an optical fiber ring reaches above 90%, thereby being good for the cascade.

The invention discloses a nonlinear polarization rotary mode-locked and wavelength tunable type L-waveband femtosecond Er-doped fiber laser and belongs to wavelength tunable type femtosecond pulse lasers. The nonlinear polarization rotary mode-locked and wavelength tunable type L-waveband femtosecond Er-doped fiber laser comprises a pumping source and an optical fiber ring cavity, wherein the optical fiber ring cavity is formed by connecting a wavelength division multiplexer, Er-doped fibers, an optical fiber isolator, an optical fiber polarizer, an optical fiber coupler and optical fibers used in a polarization controller, the pumping source is connected with the pumping port of the wavelength division multiplexer, a public port of the wavelength division multiplexer is connected to the 80% output port of the optical fiber coupler after passing through the Er-doped fibers, the optical fiber isolator and the optical fiber polarizer in sequence, and the input end of the optical fiber coupler is connected to a signal port of the wavelength division multiplexer through the polarization controller; the optical fiber isolator is connected with the optical fiber polarizer through dispersion compensation fibers, and the other devices are connected through single-mode optical fibers. The nonlinear polarization rotary mode-locked and wavelength tunable type L-waveband femtosecond Er-doped fiber laser has the advantages that the structure is simple and reliable, maintenance is convenient, external signal modulation is not needed, self-starting mode locking can be achieved, output pulses are narrow, the working performance is excellent, cost is low, and operation is easy.

The invention relates to an ytterbium doped photonic crystal fiber nonlinear polarization rotation mode-locked laser device, which belongs to the technical field of laser devices, and can directly provide laser output with high average power and high pulse energy from a laser oscillator. The laser device is mold-locked on the basis of a nonlinear polarization rotation principle, and is structurally characterized in that 976nm semiconductor laser is transmitted into an aspheric surface collimating mirror from the laser device firstly, passes by a dichroic mirror, is transmitted into a photonic crystal fiber through an aspheric surface focusing mirror, then is transmitted onto a dichroic mirror by an aspheric surface mirror in a collimated mode and reflected onto a 1 / 4 wave plate, passes by a narrow-band filtering plate and an optical isolator, sequentially passes by a half-wave plate and a 1 / 4 wave plate, finally passes by the dichroic mirror and is infiltrated into the photonic crystal fiber by the aspheric surface focusing mirror, and a resonant cavity of the laser device is formed. The laser device with the cavity has a simple structure, is easy to debug, can be used for producing laser with high average power and high pulse energy directly, and can be used for laser processing, nonlinear transformation and the like.

The invention relates to a passive mode-locked fiber laser device which includes a laser pumping source and a unidirectional annular resonant cavity. The unidirectional annular resonant cavity includes a wavelength division multiplexer, an Er doped fiber, a first optical-fiber collimator, a second optical-fiber collimator, a first 1 / 4 glass slide, a second 1 / 4 glass slide, a photoisolator, a bandpass filter, a polarization beam splitter and a 1 / 2 glass slide. The passive mode-locked fiber laser adopts nonlinear polarization rotation mode locking and utilizes the highly doped optical fiber as a gain medium so that the length of a laser cavity is reduced and the repeating frequency of the laser device is increased. Through introduction of the bandpass filter into the laser cavity, stray components and noises in the cavity are filtered so that clock jitter resulted from quantum noises is reduced. Through management of chromatic dispersion of the laser cavity, narrower pulses can be generated and wider frequency spectrum can also be obtained and intensity noises of the laser device are also reduced so that the passive mode-locked laser device is widely applicable to the field of optical-analog-digital system (OAD).

The invention discloses a tunable multi-wavelength optical fibre laser with ultra-density wavelength interval based on a semiconductor optical amplifier, belonging to the field of laser and optical communication. A gain medium in the laser is a semiconductor optical amplifier; a polarization controller is arranged at the input end of the semiconductor optical amplifier and used for regulating thepolarization state of the incidence light of the semiconductor optical amplifier; another polarization controller is arranged at the output end of the semiconductor optical amplifier and used for regulating the polarization state before light enters into the relative isolator for polarization. A birefraction optical fibre environment is formed by a 3dB coupler, the polarization controller and a polarization-preserving fibre to form a periodical filter. 90 percent of a port of a 10dB coupler is connected with a laser so that optical signals circulate continuously in a cavity, and 10 percent ofthe port is used for laser output. The nonlinear polarization rotation effect in the semiconductor optical amplifier is used for generating multi-wavelength laser with a wavelength interval less thanthe even broadened linear width of the semiconductor optical amplifier, and the polarization relevant gain property of the semiconductor optical amplifier is used for realizing tuning within a large-wavelength range of the multi-wavelength laser.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump, wherein the laser cavity further includes a normal dispersion fiber segment with a β″>0 where β″ representing a fiber dispersion, and an anomalous dispersion fiber segment with the β″<0 for generating a net anomalous 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 segment with the anomalous dispersion further includes a Photonic Crystal (PC), a Photonic Bandgap (PBG) or a higher order mode (HOM) fiber.

The invention discloses a nonlinear polarization rotation effect based all-optical adding and subtracting device. The all-optical adding and subtracting device comprises a set of input polarization controllers, a set of optical attenuators, a light-combining device, a nonlinear polarization rotation device, a light splitting device, a set of polarization controllers and a set of polarized beam splitters. The device adopts a principle as follows: after data light and non-modulated light are simultaneously injected into a nonlinear optical fiber or a nonlinear waveguide, an optical power change is introduced into a nonlinear relative phase shift, thereby resulting in the rotation of polarization states of optical signals. At the output end of the nonlinear optical fiber or waveguide, the orthogonal polarization states of multiple wavelength signals are simultaneously filtered by the light splitting device and the polarized beam splitters, so that various basic combinational logics are completed, and an all-optical half adder, a half-subtracter, a full adder and a full subtracter are realized. According to the invention, the logic operation of signals is directly completed in an optical domain, so that an electronic bottleneck is broken through, and a Tb / s-magnitude all-optical adding and subtracting operation can be realized, and therefore, the device disclosed by the invention can be applied to the fields of light-speed optical signal processing and light-speed optical switching networks and the like.

The invention discloses an all optical quantizing encoder based on nonlinear polarization rotation effects in semiconductor optical amplifiers (SOA), which belongs to the technical field of optical communication networks and mainly comprises a power allocation unit and a quantizing encoding unit based on the nonlinear polarization rotation effects in the SOAs, wherein the quantizing encoding unit mainly comprises an initial quantizing encoding module and a gain dynamic compensation module; the action of the initial quantizing encoding module is to carry out initial quantizing encoding on sampled optical pulses; and the action of the gain dynamic compensation module is to carry out gain dynamic compensation on the pulses on which the initial quantizing encoding is finished. The all optical quantizing encoder based on the nonlinear polarization rotation effects in the SOAs is capable of solving the problems that the quantizing encoder based on cross gain modulation in the SOAs is not capable of realizing high-resolution encoding and uniform quantization, and the number of the required SOAs is excessive, thereby, the all optical quantizing encoder based on the nonlinear polarization rotation effects in the SOAs has the advantages that the resolution is high, the quantization is uniform, and the number of the required SOAs is less, and simultaneously, the quantizing encoder also has the advantages of low energy consumption and convenience in photon integration and is a key technology of realizing all optical networks in future.

The invention discloses a double-cladding thulium-doped all-fiber ultrafast laser based on nonlinear polarization rotation mode locking and relates to a laser. By single-mode passive optical fibers, a beam combiner, a double-cladding thulium-doped fiber, an isolator, a polarized controller, an optical coupler and a polarizer are sequentially connected to form an annular optical-fiber resonance cavity, a pumping source injects pumping light into the annular optical-fiber resonance cavity through a pumping light input port of the beam combiner, and resonance is made in an output cavity of the output end of an optical coupler to generate soliton laser pulse. By adjustment of the polarized controller, double refraction in the cavity is changed to realize optical soliton pulse output, pulse width is 1.6 ps, pulse energy is 80 pj, pulse repetition frequency is 15MHz, 3dB band width is 4.45 nm, and the central wavelength is 2042 nm. In a 2-micrometer all-fiber laser, output of optical soliton pulse is realized.

The invention relates to a multi-wavelength synchronous output fiber laser based on nonlinear polarization rotation mode locking, which comprises a semiconductor laser, a wavelength division multiplexer, a gain fiber, a first collimating mirror, a first half wave plate, a first quarter wave plate, a first polarization beam splitter, a Faraday isolator, a glaring grating, and a silver mirror. According to the first half wave plate, a nonlinear polarization rotation technology is adopted for mode locking, a saturable absorber which is likely to be damaged can be prevented from being used, and the stability of the laser is enhanced. According to the same laser gain fiber and the nonlinear polarization mode locking device, the distance between two wavelengths under mutual cross phase modulation effects in the laser cavity is increased, and thus, a cavity length misadjustment range for two laser cavities in the case of synchronous mode locking can be increased. Through changing the angle of a beam-splitting grating, the output wavelength of the laser can be tuned, the gap between the two wavelengths can be changed through changing the position of the collimator in the spectral space, and through changing the position of the collimator away from the beam-splitting grating, the pulse spectral width and the pulse width of laser output pulses can be changed.

The invention discloses a polarization combination nonlinear rotary mode locking method. The method is characterized in that the nonlinear polarization rotary mode locking is adopted, the mode-locking pulse formed in a laser cavity is firstly separated in a pulse polarization manner, then the pulse is separated and broadened, the separated low-peak-value power pulse is magnified by virtue of gain medium, the magnified pulse is returned to be magnified for the second time after being reflected by virtue of a faraday rotator mirror, and finally the pulse is combined to obtain the pulse with high peak value power; the pulse is repeatedly and circularly magnified in the laser cavity, and the obtained laser pulse with high energy is outputted through a coupling output device. By adopting the method, the high-energy mode-locking pulse which is stably outputted can be obtained.

The invention provides a beam controlling method and a beam regulating apparatus achieved by using the adjusting photon crystal self-collimating effect, and the applications thereof. The invention is characterized in that the parts is provided with an especial beam control philosophy in the range of the frequency of the self-collimating effect. The adjusting self-collimating is realized through adjusting the color dispersion property of the self-collimating points nearby by use of the adjustable medium parameter for example the non-linear susceptibility, and the interaction of the photon energy strip structure. Moreover, the function of the consecutive adjustable diverging angle, self-locking self-collimating and special auto-conduction are achieved. The functions make an important role in the light integration and light interconnection, and can be used for designing the adjustable self-collimating wave-guide, the self-locking beam width adjusting wave-guide, the beam width controller, the adjustable beam enlarged mirror, the coupling mirror and the second pico-second grade high speed optical switch.

A coherent optical transmitter circuit is disclosed in which controlled chirp is employed, enabling the suppression of nonlinear polarization scattering in dual polarization coherent systems, such as those which employ dual polarization-quadrature phase-shift keying (DP-QPSK). By separately chirping the modulated signals of each polarization tributary signal, the polarization state of the output DP-QPSK signal varies during a time period corresponding to a symbol bit period. Such controlled variations in the output DP-QPSK signal result in the mitigation of nonlinear effects associated with the network infrastructure over which the signal is transmitted, resulting in enhanced system performance. Enhanced system performance, for example, can be seen in greater reach and improved signal quality of the transmitted signal.

The invention discloses an optical fiber link time-frequency distribution device based on femtosecond laser. The optical fiber link time-frequency distribution device comprises a main clock transmitter, an isolator, a half-wave plate, a polarization beam splitter, two quarter-wave plates, a reflecting mirror integrated with a stepping motor, a piezoelectric ceramic fiber stretcher, an optical fiber link, an Er<3+> doped optical fiber amplifier, a Faraday polariscope and a clock error detection unit composed of a balance optical cross-correlation system, a PI controller, a data acquisition card and a computer. Two beams of optical pulse signals received by the clock error detection unit are locked within a specific error range by adjusting parameters of the PI controller. The optical fiber link time-frequency distribution device adopts an erbium-doped fiber femtosecond laser locked to a hydrogen maser clock and based on nonlinear polarization evolution (NPE) as the main clock transmitter, utilizes the matching between the piezoelectric ceramic fiber stretcher and the stepping motor to compensate clock errors, achieves femtosecond-level clock synchronization errors in a kilometer-level optical fiber link and ensures long-time stability of the optical fiber link.

The invention discloses a CARS microscopic imaging apparatus and a CARS microscopic imaging method based on photonic crystal optical fiber probe excitation. The CARS microscopic imaging apparatus comprises a femtosecond laser device input light source, a pump light pulse optical path, a Stokes optical pulse optical path, high nonlinear polarization-maintaining photonic crystal optical fiber, a to-be-detected sample, a light collection objective lens and a signal detection and data processing system. According to the present invention, the high nonlinear polarization-maintaining photonic crystal optical fiber is used as the Stokes optical pulse generation device in the CARS microscopic imaging system, and is further used as the light guiding device of the pump light pulse in the system so as to make the pump light and the Stokes light output by the high nonlinear polarization-maintaining photonic crystal optical fiber be directly incident into the surface of the to-be-detected sample, the intensity and the spatial distribution of the anti-Stokes Raman scattering signal are analyzed, and the spatial distribution of the specific chemical bond in the to-be-detected sample is reconstructed; and compared to the apparatus in the prior art, the apparatus of the present invention has advantages of system structure simplifying, convenient system operation and improved system integration,and can help to push the CARS microscopic imaging system from scientific research to practical application.

The invention discloses a fast automatic mode locking method covering multi-state pulse recognition and belongs to the mode-locked laser and automatic control field. The method include the following steps that: after being subjected to photoelectric conversion and high-speed sampling, the output signals of a mode-locked laser are used for mode locking state recognition; if the result of the mode locking state recognition is a mode unlocked state, optimization is carried out; an adjusted polarization state value is inputted to a digital-to-analog converter from a computing center through a serial communication protocol according to an optimization algorithm, and is converted into four direct-current voltages; the outputted four direct-current voltages drive an electronically controlled polarization controller in the mode-locked laser, so that automatic polarization control can be realized; if the result of the mode locking state recognition is a mode-locked state, a monitoring mode is enabled; and if locking failure is detected, and rapid mode-locking resuming is successful, the monitoring mode is resumed. With the method adopted, the problem of polarization control in a passive mode-locked laser based on nonlinear polarization evolution is solved, and the mode-locked laser can quickly and automatically lock a mode and stably work under a target state.

A method for producing all-optical high-speed random number based on chaotic laser comprises the steps that produced chaotic laser is sampled by utilizing an all-optical sampling system based on a semiconductor optical amplifier-nonlinear polarization rotation effect (SOA-NPR), an all-optical quantizer based on the nonlinear polarization rotation effect (NPR) is utilized to quantize the pulse obtained after sampling, and the random number is obtained in an optical domain. The devices adopted in the method include a chaotic laser source, an all-optical sampler and the all-optical quantizer. The method is completely performed in the optical domain, the electronic bottleneck limitations can be broken through, and all-optical high-speed random codes are produced in real time. The produced random codes can be directly compatible with optical signals in an optical communication network, and the demand for modern high-speed communication safety is met.

The invention provides a space structure optical fiber laser based on two-dimensional nanomaterial mode locking. The space structure optical fiber laser comprises a pumping source used for outputting pumping laser, and an annular cavity optical path, wherein one part of the annular cavity optical path consists of gain optical fibers; the space structure optical fiber laser also comprises a two-dimensional nanomaterial saturable absorber used for mode locking, a space structure used for forming nonlinear polarization rotation and realizing hybrid mode locking, and a wavelength division multiplexer used for coupling light into the annular cavity optical path. According to the space structure optical fiber laser based on the two-dimensional nanomaterial mode locking provided by the invention, the space structure optical fiber laser mode locking is realized by adopting the two-dimensional nanomaterial saturable absorber and the space structure for forming nonlinear polarization rotation for realizing the hybrid mode locking; the optical fiber laser is compact and small in structure, relatively low in cost, and applicable to duplication in production and assembling; and the optical fiber laser has the advantages of one-way laser output, high repetition frequency, pulse width lower than 100fs magnitude, high stability, high optical beam quality and the like, so that the optical fiber laser can be widely applied to national defense, industries, medical treatment, scientific research and the like.

The invention relates to an optical frequency comb device based on an all polarization-maintaining fiber and a mode locking and frequency locking method. The generation of mode locking pulses is realized by nonlinear polarization rotation of the pulses in a spiral fiber. The repetition rate of the device is locked through a mechanical method or an optical method. Through an all polarization-maintaining fiber amplifier, a polarization-maintaining nonlinear fiber and a PPLN crystal, carrier phase zero frequency signals of the pulses are acquired; the carrier phase zero frequency signals are processed by a circuit and are then fed back to a power control device in the device or fed back to an intracavity loss control device, and locking of the carrier phase zero frequency signals is realized.Based on the all polarization-maintaining fiber, a mode-locked laser is built, the pulses generate nonlinear polarization rotation in the spiral fiber, and walk-off effects of the pulses are solved through special arrangement of multiple sections of spiral fibers. The made all polarization-maintaining fiber optical frequency comb device has the characteristics of extremely high stability and insensitivity to temperature fluctuation and mechanical vibration.

The invention discloses a double-resonant-cavity all-optical-fiber mode-locked pulse laser, and belongs to the field of laser technology, optical fiber optics and nonlinear optics. The double-resonant-cavity all-optical-fiber mode-locked pulse laser mainly comprises a pumping source, an optical fiber beam combiner, a wavelength division multiplexer, a first gain optical fiber, a second gain optical fiber, a saturable absorption body, a reflection type optical fiber Bragg grating, an optical isolator, a circulator, a total reflector, a beam splitter and a filter. A linear cavity structure or an annular cavity structure is adopted. Compared with an SESAM (semiconductor saturable absorber mirror) mode-locked, NPR (nonlinear polarization rotation) and NPE (nonlinear polarization evolution) mode-locked technology, the laser provided by the invention has the advantages that the laser mode-locked pulse can be directly output by using the double resonant cavities and the saturable absorption body, the design is simple, the structure is compact, the cost is reduced, and the system output stability can be effectively improved.

The invention belongs to the field of non-linear optical material, in particular to a gold nanoparticle loaded mesoporous titanium oxide composite film and preparation thereof. The gold nanoparticle loaded mesoporous titanium oxide composite film of the invention is composed of titanium oxide and Au, and the microstructure of the composite film is characterized in that gold nanoparticles are distributed in the pore canal of the mesoporous titanium oxide film. The gold nanoparticle in the composite film of the invention has even particle size and even distribution and has higher off-resonance third-order nonlinear susceptibility (x<3>=6.32*10<-8>esu); the composite film can avoid heat accumulation brought by nonlinear adsorption when working in off-resonance condition, which is more favorable for the practical application of nonlinear material. The preparing method of the gold nanoparticle loaded mesoporous titanium oxide composite film of the invention adopts a deposition precipitationmethod, leads in second-phase material in the mesoporous pore canal and has the characteristics of simpleness, high speed, high efficiency and the like.

A nonlinear polarization amplifier stage includes a gain medium operable to receive a multiple wavelength optical signal. The amplifier further includes a pump assembly operable to generate a plurality of pump wavelengths forming a pump spectrum comprising a plurality of peaks. The amplifier also includes a coupler operable to introduce the at least one of the plurality of pump wavelengths to the gain medium to facilitate amplification of at least a portion of the multiple wavelength optical signal through nonlinear polarization. In one particular example, at least a wavelength or an intensity of the at least one of the plurality of pump wavelengths is manipulated to affect the shape of a gain curve associated with the multiple wavelength optical signal in the amplifier stage.