144 results about "Extinction ratio" patented technology

The invention discloses a parameter measuring device and method of an optical switch and optical communication equipment, and relates to the technical field of optical switch measurement, and the parameter measuring device of the optical switch comprises an optical path module, a signal conditioning circuit, a driving module, a signal acquisition module and an upper computer. The optical path module converts the optical signal into a current signal; the signal conditioning circuit conditions the signal into a voltage signal and amplifies the voltage signal; the driving module provides a driving signal and a synchronous triggering signal; the signal acquisition module acquires a voltage signal based on the trigger signal; the upper computer calculates performance parameters of the optical switch according to the voltage signals acquired for multiple times, wherein the performance parameters at least comprise two items of insertion loss, extinction ratio, switching time and the like; according to the technical scheme, one-key measurement of performance parameters such as insertion loss, extinction ratio, switching time, polarization-dependent loss, insertion-dependent loss and repeatability of the optical switch can be realized, meanwhile, the measurement cost of the optical switch is reduced, and the test efficiency and accuracy are improved.

The invention discloses a polarization sensitive type broadband absorber based on metal-medium stacking, and relates to the technical field of micro-nano photonic devices and infrared detection. The absorber sequentially comprises a bottom-layer high-loss metal reflecting layer, a multi-layer stacked composite dielectric cavity structure and a top-layer sub-wavelength metal grating from bottom to top, according to impedance matching and interference resonance theories, a broadband absorption substrate is constructed through a multi-layer film structure at the bottom, and light energy is converted into heat energy by utilizing the high loss characteristic of bottom layer metal; plasmon resonance is excited through the top metal grating, the coupling efficiency of TM polarized light is enhanced, and TE polarized light is cut off; the above structural design successfully realizes efficient broadband absorption and high polarization extinction ratio in an infrared band. The structure is simple in design, is compatible with a CMOS technology, and has excellent wide-angle stability. And meanwhile, polarization screening can be realized without an external polaroid, and miniaturization and integration of an infrared detection system are facilitated.

The invention discloses a thin-film barium titanate electro-optical switch unit based on a composite electrode and an array thereof. The optical switch unit comprises a first waveguide optical fiber coupling module, a second waveguide optical fiber coupling module, an optical beam splitting module, an electro-optical phase shift region, an optical beam combining module, a third waveguide optical fiber coupling module and a fourth waveguide optical fiber coupling module. Wherein the composite electrode of the electro-optic phase shift region is composed of a metal electrode and a transparent conductive layer, the electrode is closer to the waveguide by utilizing the transparent characteristic of a transparent conductive material, the coupling of a light field and an electric field is effectively enhanced, and the extinction ratio is improved. Meanwhile, a barium titanate film with a high electro-optical coefficient is adopted as a waveguide material, and the performance is further optimized, so that the electro-optical switch unit has the excellent characteristics of low-voltage driving, high extinction ratio, low insertion loss and small size.

The invention relates to the technical field of optical communication, in particular to a silicon optical chip monitoring method and device, electronic equipment and a computer readable storage medium, and the method comprises the steps: obtaining an input monitoring value and an output monitoring value integrated by a silicon optical chip, the input monitoring value is an input optical power value collected by an input monitoring photodiode integrated with the silicon optical chip, the output monitoring value is an output optical power value collected by an output monitoring photodiode integrated with the silicon optical chip, and a power ratio parameter is calculated according to the input monitoring value and the output monitoring value; the power ratio parameter is compared with a preset ratio range, and when it is detected that the power ratio parameter is not in the preset ratio range, it is determined that the silicon optical chip has an optical extinction ratio abnormal risk; and outputting a detection result containing the risk that the optical extinction ratio is abnormal, so that the real-time performance of abnormal detection of the optical extinction ratio of the silicon optical chip is improved.

This invention discloses a bimetallic hybrid metasurface that achieves polarization-selective absorption and tunable liquid immersion. The metasurface consists of a three-layer structure: a bimetallic hybrid layer, a silicon dioxide layer, and a silver reflective layer. The bimetallic hybrid layer is composed of aluminum and titanium nanoribbons. The bimetallic hybrid metasurface achieves perfect absorption of incident light under x-polarized light at the resonant wavelength and specular reflection of incident light under y-polarized light, thus exhibiting a high extinction ratio. Furthermore, the absorption peak wavelength of the metasurface can be continuously and dynamically tuned by adjusting the unit period of the metasurface or by utilizing active tuning through liquid immersion. The bimetallic hybrid metasurface proposed in this invention achieves high-contrast polarization-selective absorption and possesses advantages such as simple structure, ease of integration, and dynamic tunability, thus it can be widely applied in practical applications such as novel optical polarizers and photodetectors.

The application discloses a kind of parameter measuring device of optical switch and method, optical communication equipment, it is related to optical switch measurement technical field, the parameter measuring device of optical switch includes optical path module, signal conditioning circuit, drive module, signal acquisition module and host computer;Optical path module converts optical signal into current signal;Signal conditioning circuit is conditioned as voltage signal and amplifies;Drive module provides driving signal and synchronous trigger signal;Signal acquisition module is based on trigger signal and collects voltage signal;Host computer calculates the performance parameter of optical switch according to voltage signal collected multiple times, and performance parameter at least includes two items in insertion loss, extinction ratio, switching time etc.;The technical scheme of the application can realize the one-key type measurement of the performance parameter such as insertion loss, extinction ratio, switching time, polarization dependent loss, insertion dependent loss and repeatability of optical switch, while reducing the measurement cost of optical switch, improve test efficiency and accuracy.

The present invention provides a quantum entanglement light source device that takes advantage of the benefits of using optical fibers and can compensate for the decrease in polarization extinction ratio with a simple configuration. [Solution] A quantum entanglement light source device according to one embodiment of the present invention comprises a wavelength conversion unit capable of generating polarized light with a wavelength longer than the wavelength of the pump light, and a polarization control unit provided midway through optical fibers provided on both end faces of the wavelength conversion unit, capable of controlling the polarization direction of the pump light in the wavelength range.

The invention discloses a pulse modulation laser array chip based on a double-SOA structure, which relates to the technical field of photoelectronics and comprises a substrate, a semiconductor laser array chip, an active photon integrated chip and a photon lead waveguide structure, the semiconductor laser array chip and the active photon integrated chip are arranged on the substrate; the semiconductor laser array chip and the active photonic integrated chip are in coupling connection through a photonic lead waveguide structure, the active photonic integrated chip comprises an SOA wave combining chip or an SOA chip, and the semiconductor laser array chip comprises a first SOA structure. According to the invention, a double-SOA structure is used, the problem of light leakage in a common laser array is solved, a larger modulation range and extinction ratio are realized, combined wave emission of a plurality of laser arrays is realized, the number of laser channels is increased, and the wavelength tuning range is expanded.

The application discloses a continuous variable quantum key distribution method based on an inner modulation pulse light source, which comprises the following steps: a sending end provides signal light and local light to a receiving end, or the sending end provides signal light to the receiving end, and the receiving end provides local light; the receiving end interferes the signal light and the local light, and extracts a component with channel noise and initial data from the interference result; and the receiving end processes the component with channel noise and the initial data to obtain amplitude modulation information related to the channel noise, namely, an initial key. The application makes full use of the random phase difference between the front and rear pulses generated by the inner modulation pulse light source, and makes the detection result independent of the phase difference, without any phase feedback and compensation, and the modulation mode is simpler; higher light pulse extinction ratio and light pulse intensity can be obtained, so that the transmission distance is farther, and the detection efficiency is higher; the high complexity double light source frequency locking technology can be avoided, and the system complexity is reduced.

The invention discloses a high-speed and high-extinction-ratio cascade MZI (Mach Zehnder Interferometer) electro-optical switch based on an electro-optical material. According to the electro-optical switch, a plurality of MZI structures are cascaded and integrated on an electro-optical material platform (such as lithium niobate or lithium tantalate) with an ultra-wide optical transparent window, and the initial phase error of each modulation arm is subjected to thermo-optical calibration by utilizing the refractive index change of an electro-optical material caused by temperature regulation and control; therefore, the consistency and long-term stability of the initial phase of the cascaded MZI are ensured. After thermo-optical phase calibration is completed, electro-optical refractive index regulation and control can be carried out on a plurality of phase modulation arms of the cascaded MZI at the same time only by applying a single driving voltage, and optical switch switching with the ultrahigh extinction ratio is achieved. The device has a pre-calibration function, a working point is stable and does not drift after calibration, and high-speed and high-extinction-ratio switching can be achieved only through a high-speed signal; and meanwhile, the device has the advantages of simple structure, flexible design, easiness in cascade expansion, low requirement on technological parameter tolerance and the like.

This application relates to the field of optical polarization measurement technology, specifically to a wide-spectrum, high-bandwidth static spectral modulation Stokes polarization measurement device, comprising a polarization modulation module, a spectral sampling module, and a high extinction ratio polarizer. The polarization modulation module includes a phase retarder and a linear polarizer; the spectral sampling module has sub-nanometer spectral resolution; the high extinction ratio polarizer includes a halogen tungsten lamp and a Glan Taylor prism for generating high-purity linearly polarized light; the obtained demodulation factor and the modulation spectrum acquired by the spectral sampling module are used to invert the Stokes parameters using zero-heterodyne coherent demodulation technology. This application employs a phase retarder with high birefringence, which, for the same thickness, produces an optical path difference tens of times greater than that of quartz, increasing the Stokes polarization measurement bandwidth by a factor of the response and improving the measurement accuracy of polarization spectral parameters. Simultaneously, the zero-heterodyne coherent demodulation method is used to eliminate the dispersion interference of the phase retarder through calibration.

The invention relates to the technical field of optical module automatic detection, in particular to an optical module automatic detection system and method based on a numerical control robot, and the method specifically comprises the steps: constructing a connection judgment factor through analyzing the optical signal intensity, the optical signal extinction ratio, a Q factor, the distribution condition of abnormal points in current data, and the data fluctuation condition near each abnormal point; by analyzing the abnormal data change of the current, the statistical significance difference between the current data and other parameters is reflected by using a t test algorithm, and a connection risk index during optical module detection is constructed; the connection quality of the optical module is monitored in real time through the connection risk index, when the poor degree of connection is serious, a control signal is sent out through the control module to indicate the six-axis manipulator to pull and plug the optical module again, detection errors caused by connection problems are reduced, it is ensured that the optical module is tested in the optimal state, and the test efficiency is improved. And the accuracy of optical module performance judgment is improved.

This invention relates to the field of optical thin film fabrication technology, specifically to a method for fabricating a high extinction ratio, adhesive-free polarizing beam splitter film resistant to high and low temperature environments. The method includes the following steps: S1, substrate pretreatment; S2, polarizing beam splitter film deposition; S3, adhesive-free bonding treatment; S4, annealing strengthening; and S5, post-treatment. This invention uses an adhesive-free optical contact bonding process to replace the traditional organic bonding process, completely eliminating the temperature adaptability bottleneck caused by organic adhesive layers. The bonding interface relies on intermolecular forces for adhesion, eliminating problems such as aging and debonding of organic adhesives. This allows the device to operate stably in a wide temperature range of -60℃ to 120℃, greatly improving the device's environmental adaptability and meeting the needs of extreme environments such as deep space exploration and polar observation.

The invention relates to the technical field of biological detection, and provides a biological tissue component detection device and a detection method. The biological tissue component detection device comprises a laser unit, a sample table, a polarization unit, a detector, a first scanner and a processor, the polarization unit is used for reflecting the S polarized light emitted by the laser unit to the biological tissue and filtering out the S polarized light in the mixed light reflected by the biological tissue; the detector is used for collecting light intensity of theta polarized light; the first scanner is used for acquiring space coordinates of each region of the biological tissue; and the processor is used for generating a polarization angle spectrum of the single region based on the light intensity and the polarization angle, generating a global polarization angle spectrum of the biological tissue based on the plurality of polarization angle spectrums and the plurality of space coordinates, and detecting the biological tissue based on a peak polarization angle, a spectrum width and a polarization extinction ratio of the global polarization angle spectrum. According to the biological tissue component detection device, spectrum similar substances in multiple industries can be distinguished, and the biological tissue distinguishing accuracy is improved.

The invention relates to the technical field of optical transceivers, and discloses a high-extinction-ratio coherent optical silicon optical transceiver chip and a transmitting method and a receiving method thereof. The transmitting end of the chip comprises a structure formed by cascading a modulator (102) and an optical switch (103); the receiving end comprises a simplified receiving structure consisting of a 2 * 2 coupler (104) and a single photoelectric detector (105); and all devices are integrated on a single silicon optical chip. According to the invention, the cascade architecture of the modulator and the optical switch is introduced at the transmitting end, so that the transmitting extinction ratio is remarkably improved, the direct-current leakage interference caused by the non-working ONU is effectively suppressed, and the signal-to-noise ratio and the receiving sensitivity of the system are improved. Meanwhile, the combination of the simplified receiving architecture and the silicon photon platform realizes the transceiving function with low power consumption, low cost and small volume, and can meet the requirements of a high-speed optical access scene.

A non-degenerate mode few-mode multiplexer / demultiplexer based on a four-core transmission main channel is characterized in that a transmission channel of the mode division multiplexer / demultiplexer is composed of an elliptical four-core super-mode fiber core FEC-SFC and three single-mode fiber cores, the elliptical four-core super-mode fiber core at the coordinate center serves as the transmission main channel, and the single-mode fiber cores SMF1, SMF2 and SMF3 are transmission coupling channels; the length of the transmission main channel FEC-SFC is 3.588 mm, and the lengths of the SMF1, the SMF2 and the SMF3 are respectively 3.588 mm, 1.658 mm and 1.808 mm; the mode field characteristics in the optical fiber can be changed by reasonably setting parameters such as the position, the size and the refractive index distribution of the fiber core; according to the ultra-mode fiber core, the advantages of a pure silicon dioxide fiber core, an elliptical core and an ultra-mode fiber core are fused, the mode degeneracy of LP11a / LP11b is broken, four ultra-mode multiplexing and demultiplexing of LP01, LP11a, LP11b and LP21b are achieved, the refractive index fiber core made of pure silicon dioxide is adopted, and the low-loss performance is achieved; a transmission channel with a large effective refractive index difference is adopted, and the position and the length of the transmission channel are reasonably set, so that the low-crosstalk and high-extinction-ratio performance is realized, and the low-crosstalk and high-extinction-ratio optical fiber can be used for MIMO-FREE operation.

The present application relates to the technical field of flexible touch screen detection, and specifically discloses a flexible touch screen polarization characteristic detection method based on multi-modal data fusion. The method comprises the following steps: building a multi-parameter measurement optical path system, collecting speckle characteristic data, interferometric polarization phase information data and spectral characteristic data after the flexible touch screen is transmitted; generating a multi-modal fusion feature vector through time-space alignment and feature extraction; constructing a CNN-LSTM hybrid neural network model; dynamically adjusting the parameters of the CNN-LSTM hybrid neural network model by using an adaptive algorithm; inputting the multi-modal fusion feature vector into the adjusted CNN-LSTM hybrid neural network model, and outputting the polarization degree, the extinction ratio and the polarization axis direction parameters. Through the multi-parameter measurement optical path system cooperative detection, the multi-modal data fusion and the adaptive algorithm, the present application solves the polarization characteristic drift problem caused by the deformation of the flexible screen, and significantly improves the detection accuracy and stability.

The application discloses a Brewster window stack polarization modulation device. The device comprises a Brewster window stack assembly, a clamping assembly, and an installation base. The Brewster window stack assembly comprises a plurality of optical window pieces arranged in parallel and at intervals, and the included angle between the surface normal and the incident light is a Brewster angle. The installation base has a vertical part and a horizontal part. The clamping baffle is arranged opposite to the vertical part of the installation base at intervals. The optical window pieces and the gaskets are alternately arranged in parallel at intervals. One adjusting screw is arranged on each side of the installation base. The adjusting screw passes through the clamping baffle and each gasket in sequence, and is screwed with the vertical part of the installation base. The rotation of the adjusting screw is converted into the linear motion of the clamping baffle along the support surface, so as to change the distance between the clamping baffle and the vertical part and / or realize the clamping and fixing of the Brewster window stack assembly. The device can realize linearly polarized light output with high extinction ratio and high stability in a wide range of incident angles and spectral bands.

Embodiments of the present application provide a method for obtaining optical signal and related equipment, which can amplify the optical power of the output optical signal and improve the extinction ratio. The method comprises: a laser sends an initial optical signal to a modulator according to an initial electrical signal; the modulator modulates the initial optical signal to generate a first modulated optical signal under the action of a first modulated electrical signal; the modulator sends the first modulated optical signal to an optical amplifier; the optical amplifier modulates the first modulated optical signal and amplifies the optical power under the action of a second modulated electrical signal to obtain a second modulated optical signal, the time delay difference between the first modulated electrical signal and the second modulated electrical signal is less than or equal to a preset threshold, and the modulation rates of the first modulated electrical signal and the second modulated electrical signal are equal.

The application discloses a high-polarization-extinction-ratio integrated Y waveguide structure based on a thin film lithium niobate, relates to the fields of microwave photonics, integrated optoelectronics and high-precision inertial sensing technology, and comprises a substrate, a lower cladding layer, a thin film lithium niobate layer and an upper cladding layer from bottom to top; and the polarization extinction ratio of the device is significantly improved according to the application; in view of the problem of poor polarization extinction ratio performance of the current monolithic integrated thin film lithium niobate Y waveguide due to the lack of an on-chip efficient polarization structure, the application creatively utilizes mode parity symmetry for filtering; the energy zero point position of the TE1 mode is determined by the waveguide electromagnetic field eigen equation and does not drift with the external environment temperature or stress; unlike the directional coupler relying on nanoscale gaps or the subwavelength grating with a minimum line width; the end-to-end transmission loss of the polarization and filtering of the application can be controlled at a very low level, so that the optical power margin and the overall signal-to-noise ratio of the fiber-optic gyroscope system detection end are significantly improved.

An object is to provide a polarizing element capable of reducing insertion loss and increasing extinction ratio by adjusting the particle diameter of metal microparticles.The polarizing element (1) of the present disclosure comprises a glass substrate (2), a plurality of cavities (3) formed inside the glass substrate extending in one direction, and metal microparticles (4) arranged within each cavity having a volume smaller than the cavities, and is wherein: an average diameter of the metal microparticles, along a transversal direction orthogonal to a longitudinal direction of the cavities, is 20 nm or less, and a particle diameter of the metal microparticles, at a cumulative frequency of 90%, is 30 nm or less.

The application provides a high-extinction-ratio optical fiber amplifier, which is composed of a first gain optical fiber, an optical blocker and a second gain optical fiber arranged in sequence along an optical path direction, and a pump source is connected to the second gain optical fiber through a beam combiner, wherein the optical path direction of the pump source is opposite to the signal light direction of the optical fiber amplifier; the optical blocker is composed of a double-fiber collimator, a roof prism, a first combination prism, a rotator and a second combination prism arranged in sequence with intervals, and a signal light filter is further arranged in the optical blocker; and the double-fiber collimator is connected with the first gain optical fiber and the second gain optical fiber respectively. The application has a reasonable structure design, filters out the amplified spontaneous emission light generated in the amplification process, reduces the index requirement and cost of the filter through the signal light filter twice, uses the residual pump light in the second amplification as the pump light in the first amplification, realizes the reverse optical isolation protection between the two-stage amplifiers, and improves the extinction ratio of the amplifier as a whole.

The invention relates to a method for growing a terbium lithium fluoride magneto-optical crystal by using a fluxing agent. The process comprises the following steps: (1) fully mixing a fluxing agent with raw materials; (2) putting the mixture into a crucible, feeding the crucible into a high-temperature molten salt furnace, vacuumizing the furnace, and introducing protective gas; and (3) controlling the heating rate, heating until the mixture is completely molten, and keeping the temperature for several hours. And (4) slowly cooling until crystals are completely separated out. And (5) annealing to room temperature to obtain the terbium lithium fluoride crystal. Tests show that the terbium lithium fluoride crystal prepared by the method is good in quality, large in extinction ratio and high in damage threshold, has relatively high transmittance and relatively strong magneto-optical performance in wave bands of 505nm, 633nm, 880nm and 1064nm, and is expected to be practically applied to magneto-optical devices such as magneto-optical isolators, Faraday rotators and the like.

This invention relates to a method, apparatus, and system for optimizing the sensitivity, extinction ratio, and EMI of long-distance optical modules. The method mainly includes: detecting the output sensitivity of the optical module at different temperatures; compensating and adjusting the voff voltage based on the sensitivity shift at different temperatures; after compensating and adjusting the voff voltage, compensating and adjusting the bias current based on the optical power shift at different temperatures; detecting the output extinction ratio of the optical module at different temperatures; compensating and adjusting the Vmod voltage based on the extinction ratio shift at different temperatures; detecting the EMI of the optical module at different temperatures; if the EMI is unqualified, compensating and adjusting the Vmod voltage; if the EMI is still unqualified after multiple compensation and adjustments of the Vmod voltage, compensating and adjusting the RX amplitude voltage and RX pre-emphasis voltage to ensure that the sensitivity, extinction ratio, and EMI of the optical module are all qualified. This invention can optimize the sensitivity and extinction ratio of the optical module to the optimal value at various temperatures while ensuring EMI compliance.

The application relates to the technical field of bionic polarization navigation sensors, and provides a polarization sensor calibration method and a calibration device introducing an extinction ratio. The method first establishes a mapping relationship between voltage responses of each channel of a polarization sensor and parameters such as the extinction ratio, the light intensity of incident light, the polarization degree and the polarization angle to obtain a sensor output equation; then, the calibration of three unknown parameters, namely the extinction ratio of the polarization sensor, the proportional coefficient of the response and the polarization plate detection angle, is realized in two steps. In the first step, the polarization sensor output is obtained under an indoor standard linearly polarized light source, and the extinction ratio is calculated by using curve fitting; in the second step, on the basis of the known extinction ratio, the two parameters, namely the proportional coefficient of the response and the polarization plate detection angle, are calibrated by using the sensor output data obtained in the first step. The method introduces the extinction ratio in the sensor output equation and gives a specific mathematical expression, perfects the sensor calibration model and proposes a calibration method for the polarization sensor under a low extinction ratio condition.

The application relates to the technical field of optical communication, in particular to a silicon optical chip monitoring method and device, electronic equipment and a computer readable storage medium, the method comprising the following steps: acquiring an input monitoring value and an output monitoring value integrated by a silicon optical chip itself, wherein the input monitoring value is an input optical power value collected by an input monitoring photodiode integrated by the silicon optical chip itself, the output monitoring value is an output optical power value collected by an output monitoring photodiode integrated by the silicon optical chip itself, a power ratio parameter is calculated according to the input monitoring value and the output monitoring value, the power ratio parameter is compared with a preset ratio range, when it is detected that the power ratio parameter is not in the preset ratio range, it is determined that the silicon optical chip has an abnormal risk of optical extinction ratio, and a detection result containing the abnormal risk of optical extinction ratio is output, so that the real-time performance of abnormal detection of the optical extinction ratio of the silicon optical chip is improved.

The invention provides a spot size converter structure and an optical system. The spot size converter structure comprises a substrate, a coupling layer and a covering layer. The coupling layer is designed to be a first waveguide, a slope waveguide and a second waveguide which are sequentially connected in the optical path transmission direction. The first waveguide has a first thickness, the width of the first waveguide is gradually increased from a first width at the beginning to a second width at the tail end along the optical path transmission direction, and the first waveguide is configured to have lower transmission loss to TE0 mode light than to TM0 mode light; the slope transition section has a second width, and the thickness of the slope transition section is gradually increased from the initial first thickness to the tail end second thickness; the second waveguide has a second thickness and a second width. A polarization selection (polarization) function is realized through the front-end first waveguide, adiabatic transition of a light field is realized through the middle-end slope waveguide, and the rear end is connected with the waveguide, so that the polarization performance of the spot size converter is improved, and optical coupling between a chip and an optical fiber with a high extinction ratio requirement is met.

The invention belongs to the technical field of millimeter wave photoelectric devices, and particularly relates to a double-line waveguide polarization rotator model design method. The method comprises the following steps: collecting polarization rotation parameters including a target rotation angle, a working frequency band and an insertion loss requirement; the method comprises the steps that simulation software is used for building a geometric model, simulating metal wires and multiple dielectric layers sequentially surrounding from inside to outside, a double-wire waveguide basic model is built, the two metal wires are parallel and not coplanar and form a waveguide structure, ports are set as optical signal input and output ends, the rotation angle and the optimal length of the metal wires are adjusted, and a three-dimensional simulation model is built; after mode analysis verification, a model entity is obtained through 3D printing, the polarization state and the polarization extinction ratio are tested, and the performance is evaluated; and finally, iterative optimization is carried out until the optimal rotation angle is obtained. The method supports flexible regulation and control of the polarization rotation angle, the influence of external factors on the performance is small, efficient and accurate control over the light polarization state can be achieved, and the method is suitable for the fields of terahertz communication, imaging and the like.

The invention relates to the technical field of metasurface electro-optical devices, in particular to a low-loss mid-infrared electro-optical modulator based on graphene and ITO and a preparation method thereof, SiO2, Al2O3, graphene, TiO2 and ITO are sequentially arranged in the electro-optical modulator from bottom to top, and Si is embedded in SiO2 to serve as a central waveguide. Single-layer graphene and ITO with the thickness of 30 nm are placed in a staggered mode to form a heterojunction, change of carriers in the Si waveguide is caused, and then modulation of the change of effective refraction in the Si waveguide is achieved; besides, the graphene and the ITO form a parallel-plate capacitor, the switching energy of the modulator is reduced, high modulation efficiency is achieved, and finally, metal electrodes are placed on the graphene and the ITO respectively, so that voltage directly controls heterojunction. According to experimental verification, a high extinction ratio is achieved under low insertion loss, and multi-rate modulation can be achieved.

The invention relates to a 50dB extinction ratio silicon dioxide cladding polarization conversion beam splitter and a design method thereof, and the polarization conversion beam splitter comprises a substrate, an upper cladding and top silicon; the top silicon comprises an input waveguide, a polarization conversion area, a mode conversion area, and a first output waveguide and a second output waveguide which are connected with the mode conversion area; the polarization conversion area is a ridge waveguide and comprises a rib part and a ridge part; the widths of the rib parts and the ridge parts are gradually increased in the direction from input to output; the polarization conversion area is used for converting a TM0 mode in the input waveguide into a TE1 mode while the TE0 mode in the input waveguide is kept unchanged; the TE0 mode is kept unchanged in the mode conversion area and is output based on the first output waveguide, and the TE1 mode is converted into the TE0 mode in the mode conversion area and is output at the second output waveguide. The scheme has the advantages of compact size, high extinction ratio, simplicity in processing, small size and the like.