49results about How to "Reduce polarization sensitivity" patented technology

A waveguide magneto-optic sensor provides a signal indicative of the value and / or direction of a detected magnetic field by a spectral shift of the characteristic resonant spectral feature of the sensor is disclosed. The sensor does not suffer from vibrations, fiber bending or other light intensity noise and provides an absolute self-referencing signal. The sensor elements can easily be coupled to optical fibers and read with scanning spectrometers or scanning lasers calibrated against NIST-traceable gas absorption standards.

The invention discloses a super-luminescent diode and a method for manufacturing the same. The super-luminescent diode comprises a substrate. The method includes sequentially forming a buffer layer, a lower limiting layer, an active region, an upper limiting layer and a first p-type covering layer on the substrate so as to form a primary epitaxial slice by an epitaxial growth technology; sequentially growing a second p-type covering layer and an n-type covering layer on the surface of the primary epitaxial slice so as to form a secondary epitaxial slice by the epitaxial growth technology; growing a covering layer and a contact layer on the surface of the secondary epitaxial slice so as to form a tertiary epitaxial slice by the epitaxial growth technology; and manufacturing the tertiary epitaxial slice into a super-luminescent diode chip by photoetching, etching, slice grinding and sputtering processes sequentially, and coating an antireflection film on a light emergent end surface of the chip. The super-luminescent diode and the method have the advantages of low polarization sensitivity and ripple coefficient, high power, wide spectrum and the like.

The invention discloses a double-diffraction-level Offner imaging spectrometer and belongs to the technical field of hyperspectral imaging. The double-diffraction-level Offner imaging spectrometer comprises an Offner convex grating spectral imaging system and a dual-waveband area array photoelectric detector. The dual-waveband area array photoelectric detector is formed by coaxially stacking or parallelly manufacturing and interlacing two kinds of photosensitive elements responding wavebands. Primary diffraction light and secondary diffraction light are adopted by optical gratings in the spectral imaging system simultaneously to be used as effective work levels; the photoelectric detector receives the corresponding primary diffraction light and secondary diffraction light respectively at the same time. According to the double-diffraction-level Offner imaging spectrometer, the dual-waveband area array photoelectric detector is used for being matched with optical grating double-diffraction-level spectrum bands, simultaneous detection of the primary diffraction wavebands and secondary diffraction wavebands is achieved, the working spectral region of the spectrometer is enlarged, and diffraction efficiency is improved; it is facilitated that the overall polarization sensitivity of the spectrometer is reduced; according to the dual-waveband area array photoelectric detector, the light path structure is simplified, the spectrometer size and weight are reduced, and alignment of space dimension pixels of two wavebands and alignment of primary and secondary diffraction frequency doubling wavelengths are automatically achieved.

A polarization-independent optical switching system capable of rerouting light signals is disclosed. The system includes a plurality of switching cells, each including a pair of bus waveguides that are formed in different planes above a substrate. Each bus waveguide supports low-loss propagation of both the TE- and TM-polarization modes and are optically decoupled when the switch is in an unswitched state. In its switched state, a shunt waveguide that also supports low-loss propagation of both polarization modes is moved into proximity with both bus waveguides to form a pair of adiabatic directional couplers that enable the light signal to evanescently couple between each bus waveguide and the shunt waveguide. As a result, the path of a light signal through the switching cell is reconfigured.

The invention relates to a method and a device for erasing and interposing a differential 8-phase shift keying / amplitude shift keying (D8PSK / ASK) orthogonal optical label based on an electro-absorption modulator (EAM). A coupler divides orthogonal optical label information into two paths with the same power; amplitude information in an orthogonal modulating signal is demodulated by an upper branch signal through an amplitude shift keying signal demodulator, and the demodulated amplitude information is logically negated and loaded onto an electricity input port of the EAM through a phase reverser; a lower branch signal is loaded onto an optical input port of the EAM after being delayed and amplified so as to erase the amplitude information on an optical carrier signal; and an optical band pass filter filters chirp of an optical carrier on which the old label information is erased, the filtered optical carrier is loaded onto the optical input port of the EAM after an Er-doped fiber amplifier amplifies the power of the filtered optical carrier, and new label information is loaded onto the amplitude of the optical carrier in an amplitude shift keying modulation mode so as to finish the interposing of a new label. The EAM does not have side effect on a load when the label is erased and interposed, and has chirp controllability, low driving voltage, low polarization sensitivity, small volume and low price, so that the whole network system has a simple structure and low cost, and promotes the development of the full optical label switching technology.

A sub-wavelength thin-film metal grating is placed inside a liquid crystal variable optical retarder at a selected distance from a reflective electrode to form a reflective half wave plate, thereby reducing polarization dependence of the optical retardation generated by the variable optical retarder. The approach enables to form within the device the reflective half wave plate that is suitably thin without modifying the reflective electrode of the device.

The embodiment of the invention discloses a photodiode and a manufacturing method thereof, relating to the field of opto-electrical technology, wherein the photodiode is capable of reducing the energy loss. The photodiode comprises a substrate positioned on a bottom layer, a lower cladding layer boss covering the substrate, an incident wave core guiding layer covering the lower cladding layer boss, an upper cladding layer covering the incident wave core guiding layer, an optical matching layer positioned above the upper cladding layer and an avalanche photodiode positioned above the middle part of the back end of the optical matching layer, wherein the width of the lower cladding layer boss at the tail end in the incident wave direction is wider than that of the beginning end in the incident wave direction, both sides of the lower cladding layer boss at the tail end in the incident wave direction are parallel, and both sides of the lower cladding layer boss at the beginning end in the incident wave direction are parallel; and the optical matching layer comprises an optical matching layer front end and an optical matching layer back end, wherein the optical matching layer front end comprises at least one air seam extended along the incident wave direction, and the optical matching layer front end is divided into characteristic units partitioned by the air seams. The embodiment of the invention is applied to manufacturing the photodiode.

A sub-wavelength grating is placed inside a liquid crystal variable optical retarder to reduce polarization dependence of the optical retardation generated by the variable optical retarder. A small thickness of the sub-wavelength grating, as compared to a conventional waveplate, reduces the driving voltage penalty due to the in-cell placement of the sub-wavelength grating.

An optical beam profiler using a spatial light modulator and photodetector. In an embodiment, the spatial light modulator is a two-dimensional (2-D) small tilt digital micromirror device. The profiler features fast speed, digital controls, low polarization sensitivity, and high measurement repeatability. The 2-D multi-pixel device-based profiler allows the use of several beam profile measurement concepts including moving knife edge, scanning slit, moving pinhole, variable aperture, and 2-D photodiode array. The proposed digital optical beam profiler can be implemented with any type of digitally operated 2-D spatial light modulator device such as using liquid crystals, magneto-optics, multiple quantum wells, electro-optic polymers, and photonic crystals.

A label-free imaging-based flow cytometer that measures size and cell protein concentration simultaneously is disclosed. Cell protein concentration adds a parameter to cell classification that improves the specificity and sensitivity of flow cytometers without the requirement of cell labeling. The system uses coherent dispersive Fourier transform to perform phase imaging at flow speeds as high as a few meters per second. To retrieve cell information in real-time, an analog signal processing system based on quadrature phase demodulation is described.

The invention discloses a superconducting fractal nanowire single-photon detector and a preparation method thereof. The single-photon detector comprises a substrate, nanowires, a nano antenna, a hydrogen silsequioxane layer and a silver reflecting layer, wherein the nanowires are arranged in a fractal manner and are used for achieving insensitive absorption and polarization of the nanowires on light in two polarization states; and an array nano antenna is added on the basis of the nanowires. The preparation method comprises the following steps: sputtering a layer of superconducting material on the substrate by a magnetron sputtering method; preparing an electrode in a manner of combining photoetching and electronic beam evaporation; the fractal nanowire is prepared in a manner of matching electron beam exposure with reactive ion beam etching; and the nano antenna is prepared in a manner of combining the electron beam exposure with the electronic beam evaporation. According to the superconducting fractal nanowire single-photon detector, the polarization sensitivity of the superconducting nanowire single-photon detector is lowered; the polarization sensitivity is less than 0.02; the absorption efficiencies of two orthogonal polarization states reach 80%; the wideband absorption efficiency is higher than 70%; and the superconducting fractal nanowire single-photon detector is applicable to various superconducting materials.

The light amplifier includes InP substrate, n type InP buffer layer, active region in tensile strain structure of quanta trap, O type InP cladding layer, P type InGaAs contact layer, and electrodes in top and bottom layers. Characters are that AlGalnAs is adopted in active region so as to prevent electrons to pass through barrier layer causing leak, and improve high temperature characteristics. The invention is low sensitive to polarization, and provides good temp characteristic, applicable to optical network, optical integration and photoelectron integration.

A polarization-independent optical switching system capable of rerouting light signals is disclosed. The system includes a plurality of switching cells, each including a pair of bus waveguides that are formed in different planes above a substrate. Each bus waveguide supports low-loss propagation of both the TE- and TM-polarization modes and are optically decoupled when the switch is in an unswitched state. In its switched state, a shunt waveguide that also supports low-loss propagation of both polarization modes is moved into proximity with both bus waveguides to form a pair of adiabatic directional couplers that enable the light signal to evanescently couple between each bus waveguide and the shunt waveguide. As a result, the path of a light signal through the switching cell is reconfigured.

The invention is directed to a Schiefspiegler telescope with three reflecting surfaces, preferably for observing the earth from space, particularly for imaging radiometers. It is the object of the invention to find a novel possibility for realizing a reflector telescope without vignetting which permits a simple construction and a simple adjustment of the reflecting surfaces relative to one another. According to the invention, in a Schiefspiegler telescope with three reflecting surfaces whose mirror axes are arranged within a plane, this object is met in that the primary reflecting surface and tertiary reflecting surface are convex surfaces of identical shape which are arranged symmetrically with respect to an axis of symmetry, and in that the secondary reflecting surface is arranged symmetric to the primary reflecting surface and tertiary reflecting surface and so as to be rotationally symmetric around the axis of symmetry so that all three reflecting surfaces have an axially symmetric mirror arrangement with respect to design in which the optical imaging is transmitted to a receiver in the manner of an off-axis telescopes.

A monolithic, Indium Phosphide (InP) differential phase-shift keying (DPSK) or differential quadrature phase shift keying (DQPSK) receiver that exhibits low polarization sensitivity.

The invention discloses an electromagnetic super surface complementary structure-based environment radio-frequency micro energy collection device, which comprises a dielectric substrate, wherein a metal floor is laminated on the back surface of the dielectric substrate; a metal patch structure is laminated on the front surface of the dielectric substrate; the metal floor is in a square form and the side length is equal to that of the square on the surface of the dielectric substrate; the metal patch structure is in the square form and the side length is smaller than that of the square on the surface of the dielectric substrate; the metal floor, the metal patch structure and the dielectric substrate are coaxial; the dielectric substrate is of a rectangular structure of which the surface is in the square form; metalized through holes are arranged on the diagonal lines of the surface of the dielectric substrate and are connected with the metal patch structure laminated on the front surface of the dielectric substrate; and the metalized through holes are connected with the metal floor through loading resistors. The electromagnetic super surface complementary structure-based environment radio-frequency micro energy collection device is simple and compact in structure, can keep high load energy collection efficiency within a wide-angle incident range when an incident electromagnetic wave is in an arbitrary polarization mode, and is wide in application.

The invention discloses a two-dimensional binary blazed grating with a low degree of polarization, which is a cylindrical sub-wavelength microstructural transmission grating with the same height and characterized in that grating units are periodically arranged in two orthogonal directions. Each grating unit includes a plurality of sub-units, and different sub-units have the same width but different dielectric duty cycles. According to the two-dimensional binary blazed grating provided by the invention, grating grooves are of an equal-height binary structure, can be prepared according to a single-step exposure method such as electron beam exposure or laser direct writing. Compared with sawtooth grooves with ideal morphology, the grating grooves is manufactured more easily; and meanwhile, the two-dimensional binary blazed grating has the diffraction characteristics of high diffraction efficiency and low polarization sensitivity, has no polarization at the reference wavelength and is applicable to a grating type imaging spectrometer with high signal-to-noise ratio and high radiation measurement accuracy requirements.

The invention discloses an optical switch array chip based on a digital optical phase conjugation principle. A multi-mode interference device and a digital optical phase conjugation reflector are used for constituting a 1*(M1-2)*K1 third-level optical switch subsystem, then q 1*(M1-2)*K1 third-level optical switch subsystems are in series connection in the longitudinal direction to form a 1*M*K1 second-level optical switch subsystem, further, p 1*M*K1 second-level optical switch subsystems and p-1 connectors are in series connection in the transverse direction to form a 1*M*K first-level optical switch subsystem, and finally N 1*M*K first-level optical switch subsystems connected to N input optical waveguides share M output optical waveguides, and an N*M*K optical switch array is formed in a parallel connection mode. The digital optical phase conjugation principle is used in the optical switch array, non-blocking optical switching can be conducted on K different wave lengths, and the optical switch array chip based on the digital optical phase conjugation principle is particularly suitable for optical switching and optical intersecting interconnection of optical communication network nodes and also can be used for optical interconnection between chips and optical interconnection inside an optical computer.

The invention, which belongs to the technical field of the high-power millimeter-wave antenna engineering, discloses a Q-band high-power millimeter-wave band-stop frequency selective surface comprising a bracket, a fixed circular ring, a mounting baffle ring and a circular metal plate. The circular metal plate is arranged in a clamp groove formed by the fixed circular ring and the mounting bafflering and can rotate freely around the center; and units distributed periodically are arranged on the circular metal plate. The units consist of circular holes and shuttle crossed holes; and because the units are in a 90-degree rotating symmetric manner relative to the center, the structure has extremely low sensitivity. According to the invention, the two kinds of aperture structures arranged on the circular metal plate periodically are arranged compactly, so that the relative spaces between the units are reduced and thus the influence of the grating lobe is reduced; adjacent sides of the units are connected by arc segments, thereby reducing the local field intensity at the corner angle, improving the power capacity of the device, and meeting the requirement of high-power work; and the frequency selective surface has a simply designed structure and a good cooling performance.

The invention discloses an OOFDM signal-based low-cost low-polarization sensitive wide tunable wavelength conversion device and method, and belongs to the field of all-optical wavelength conversion. Adirect modulation laser is adopted to realize light intensity modulation to generate an optical OFDM signal, a polarization diversity structure is adopted, the coupled signal light and pump light aredivided into two mutually orthogonal polarization modes (X polarization direction and Y polarization direction) by a polarization beam splitter, FWM-based all-optical wavelength conversion on the same polarization state is separately realized in two SOA, the two mutually orthogonal polarization modes after FWM are coupled together by a polarization beam combiner, then the converted optical OFDM signal is filtered by an optical band pass filter and is converted into an electric OFDM signal after photoelectric detection, and the OFDM signal is received by a receiver. According to the OOFDM signal-based low-cost low-polarization sensitive wide tunable wavelength conversion device and method, no additional external modulator is required to modulate the signal, the system cost is reduced; andthe OOFDM signal-based low-cost low-polarization sensitive wide tunable wavelength conversion device is simple in structure, and has the advantages of wide adjustment, low polarization sensitivity, easy system integration and high practicability.

Described herein is an optical phase modulator (20) including a liquid crystal element (22), disposed between a pair of opposing electrodes (24) and (26). The electrodes (24, 26) are electrically driven for supplying an electric potential V across the liquid crystal element (22) to drive the liquid crystals within element (22) in a predetermined configuration. Electrode (26) includes a grid of individually drivable pixel regions (28), at least some of which include a sub-wavelength grating structure that provides an anisotropic refractive index profile in orthogonal lateral dimensions, thereby creating an effective material form birefringence. Light incident through liquid crystal element (22) and onto electrode (26) is reflected and experiences a relative phase difference of 180° between its constituent orthogonal polarization components, thereby rotating each polarization component into the orthogonal orientation upon reflection.

A coupler structure based on graphene and three layers of super-surfaces relates to the field of photonic integrated devices and comprises the following parts of at least one first layer of super-surface, at least one second layer of super-surface and a third layer of super-surface that are not contacted mutually, wherein the third layer of super-surface is located at the bottom; an insulator structural layer; a graphene structural layer and a substrate that are respectively arranged on upper and lower surfaces of the insulator structural layer, wherein the refractive indexes of the first andsecond layers of super-surfaces are greater than that of a first insulating layer, and the refractive index of the third layer of super-surface is greater than that of a first sub-structure. By designing the three layers of super-surfaces and the graphene structural layer in the coupler structure provided by the invention, the beam propagation path and effective refractive indexes of each layer are adjusted by the three layers of super-surfaces, the contrast of refractive indexes of the first sub-structure and the third layer of super-surface is reduced, and the operation bandwidth of the coupler is effectively increased; the graphene structural layer can further increase the operation bandwidth of the coupler, and the arrangement structure of matrix unit arrays with three layers of super-surfaces can effectively improve the coupling efficiency of the coupler.

The invention provides a photoelectric monolithic integration system based on a multi-material system. According to the system, an indium phosphide-silicon laser, a silicon passive photonic device, asilicon nitride passive photonic device, a silicon nitride-lithium niobate electro-optical modulator, a germanium-silicon detector and an electronic circuit are integrated on the same substrate, so that the size of a photoelectric system is reduced, the electrical and optical interconnection distance is reduced, and the adverse effect of parasitic parameters on the integrated system is greatly reduced. The packaging between the optical path module and the circuit module is avoided, and the packaging cost is reduced. The advantages of excellent electro-optical performance of the lithium niobatematerial, low loss, low polarization sensitivity and high process tolerance of the silicon nitride material and high refractive index of the silicon material are exerted, and a monolithic photoelectric integrated system with excellent performance is realized.

The invention belongs to the technical field of optical detection, and relates to a superconducting nanowire single-photon detector and a preparation method thereof. The superconducting nanowire single photon detector comprises a substrate; a reflecting layer which is positioned on the surface of the substrate; a detection layer which is located on the surface of the reflection layer and used fordetecting photons, and the detection layer comprises a plurality of superconducting nanowire units; and a matching layer which is at least located on the surface of the superconducting nanowire unit,wraps the superconducting nanowire unit and is at least used for reducing the polarization extinction ratio of the superconducting nanowire unit; by arranging the matching layer coating the superconducting nanowire unit in the superconducting nanowire single-photon detector, the polarization extinction ratio of the superconducting nanowire single-photon detector can be reduced by utilizing the matching layer, so that the polarization sensitivity of the superconducting nanowire single-photon detector is reduced, the application field of the superconducting nanowire single-photon detector is expanded. And the detection accuracy and repeatability are improved.

The invention relates to a method of reducing polarization dependence in planar optical waveguides using index and coefficient of thermal expansion (CTE) matched material between the optical waveguide core and the cladding layer. For coupled mode devices such as the directional coupler or mode conversion horn polarization sensitivity has been linked to birefringence in the cladding, since their operation is dependent on co-propagation of fundamental and higher order mode(s), which are not as strongly confined to the waveguide core. Polarization sensitivity can be reduced by reducing the CTE mismatch between the core and cladding, or by moving the birefringence away from the core / cladding boundary, or both. To accomplish this, silica material, or similar material for refractive index (RI) and CTE matching is applied between the core and cladding to waveguide features where significant transmission occurs in the cladding.

The invention relates to a method of reducing polarization dependence in planar optical waveguides using index and coefficient of thermal expansion (CTE) matched material between the optical waveguide core and the cladding layer. For coupled mode devices such as the directional coupler or mode conversion horn polarization sensitivity has been linked to birefringence in the cladding, since their operation is dependent on co-propagation of fundamental and higher order mode(s), which are not as strongly confined to the waveguide core. Polarization sensitivity can be reduced by reducing the CTE mismatch between the core and cladding, or by moving the birefringence away from the core / cladding boundary, or both. To accomplish this, silica material, or similar material for refractive index (RI) and CTE matching is applied between the core and cladding to waveguide features where significant transmission occurs in the cladding.

A sub-wavelength grating is placed inside a liquid crystal variable optical retarder to reduce polarization dependence of the optical retardation generated by the variable optical retarder. A small thickness of the sub-wavelength grating, as compared to a conventional waveplate, reduces the driving voltage penalty due to the in-cell placement of the sub-wavelength grating.

A label-free imaging-based flow cytometer that measures size and cell protein concentration simultaneously is disclosed. Cell protein concentration adds a parameter to cell classification that improves the specificity and sensitivity of flow cytometers without the requirement of cell labeling. The system uses coherent dispersive Fourier transform to perform phase imaging at flow speeds as high as a few meters per second. To retrieve cell information in real-time, an analog signal processing system based on quadrature phase demodulation is described.