A wire gridpolarizer with double metallayers for the visible spectrum. Parallel dielectriclayers having a period (p) of 10˜250 nm and a trench between adjacent dielectriclayers overlie a transparent substrate. A first metal layer having a first thickness (d1) of 30˜150 nm is disposed in the trench. A second metal layer having a second thickness (d2) of 30˜150 nm and a width (w) overlies on the top surface of each dielectric layer. The first and second metal layers are separated by a vertical distance (l) of 10˜100 nm. The first thickness (d1) is the same as the second thickness (d2). A ratio of the width (w) to the period (p) is 25˜75%.
The invention discloses a polaroid sheet with a subwavelength grating structure, which comprises a transparent substrate, a dielectricgrating, a first metal layer and a second metal layer. The dielectricgrating is provided with ridges and grooves which are periodically arranged at intervals, the first metal layer is covered on the ridges of the dielectric grating, the second metal layer is covered in the grooves of the dielectric grating, and the period of the dielectric grating is less than the wavelength of incident light. The invention is characterized in that: a high refractive indexdielectric layer is arranged between the transparent substrate and the dielectric grating, and the refractive index of the high refractive indexdielectric layer is between 1.6 and 2.4. The transmission efficiency and the extinction ratio of TM light of the polaroid sheet are improved by adding the high refractive index dielectric layer between the transparent substrate and the dielectric grating. In the whole visible light waveband, the polaroid sheet has high transmission efficiency, high extinction ratio, and wide incident angle range. In the process, a nano-imprint technique is adopted to process and produce, the production process is simple and convenient and is easy to operate, an etching process is not needed, and the processing cost is reduced.
The making process of lithium niobate modulator includes making substrate with lithium niobate crystal with proper crystalcutting direction and electric field utilizing direction; making light waveguide on the lithium niobate crystal; making modulating electrodes including central signalelectrode and earth electrode and to form push-pull structure with the light waveguide; making microstrip matching structure in the input and output of the modulating electrodes; and setting buffering layer structure between the modulating electrode and light waveguide. Owing to the smart design of the modulating electrodes, the light waveguide and the matching structure in between, the lithium niobate modulator has high modulating rate, low insertion loss, high extinction ratio, low hemi-wave voltage, less electric reflection, and high reliability.
In a Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) utilizing a conventional downstream optical signal reusing method, there is an inventory problem that different optical transmitter types need to be provided for the operation, management, replacement, etc. of a system. A WDM-PON system according to the present invention, includes: a seed light (SL) unit generating a seed light whose wavelength intervals and center wavelengths are adjusted using at least one seed light source; an optical line terminal (OLT) receiving the wavelength-multiplexed seed light from the seed light unit, transmitting a downstream optical signal to a subscriber of the WDM-PON, and receiving a upstream optical signal from the subscriber; and an optical network unit (ONU) receiving the downstream optical signal from the OLT, flattening and modulating the downstream optical signal with upstream data so that the downstream optical signal is reused for carrying upstream data. It is possible to improve the quality and reliability of downstream transmission by sufficiently increasing an extinction ratio, and improve the quality and reliability of upstream transmission by sufficiently flattening an input downstream optical signal in a semiconductoroptical amplifier.
The invention discloses a device and a method for performing offset point automatic locking on an electrooptical modulator with ultrahigh extinction ratio. The offset point automatic locking device of the electrooptical modulator with ultrahigh extinction ratio comprises a laser, an electrooptical modulator, an optical switch, an electrooptical modulator offset voltagecontrol system and a clock synchronization module, wherein the electrooptical modulator offset voltagecontrol system comprises an electrooptical conversion signal amplification module, an analog-digital conversion module, a controller and an output driving circuit; and the clock synchronization module is used for opening an synchronization optical switch, inputting modulated electrical impulse of the electrooptical modulator radio-frequency end, and the disturbance leading-in time of the direct-current offset end of the electrooptical modulator. The method is characterized in that ultrahigh extinction ratio pulsed light output is realized through the cascade connection of the electrooptical modulator and the optical switch, and through controlling the offset voltage of the electrooptical modulator, the electrooptical modulator operates at an appropriate working spot stably. According to the invention, the offset voltage of the electrooptical modulator is controlled automatically; the pulsed light extinction ratio output by the device is improved greatly; and the energy is higher and much stable.
Broadband optical switches based on adiabatic couplers having a pair of asymmetric waveguides with variable curvature sections include in a 2x2 configuration based on a Mach-Zehnder interferometer two such adiabatic couplers, and in a 1x2 or 2x1 configuration an adiabatic coupler and an Y-splitter. Each adiabatic coupler includes two waveguide branches of different but constant widths having curved sections with varying radii, separated over a coupling length by a changing spacing therebetween and blending in an asymmetric intersection area, and two symmetric branches. In the 2x2 switch, the two adiabatic couplers face each other with their respective symmetric branches, and are connected by the two identical arms along a main propagation axis in a mirror image. The utilization of the variable curvature adiabatic couplers in silica MZI switches on a silicon substrate provides switches with an exceptional broadband range (1.2-1.7 mum), very high extinction ratios (>35 dB), low fabrication sensitivity and polarization independent operation. The switches are significantly smaller than known broadband switches, have significantly smaller excess loss, faster switching time and low power consumption.
A polarized white light emitting diode provides a polarized white light to decrease glare, and increase the extinction ratio. A LED chip is disposed in a cavity between a reflection substrate and a metallic wire-grid polarizing layer, and emits a first color light. The metallic wire-grid polarizing layer is disposed under and in contact with a transparent substrate. A phosphor layer covers over the LED chip, and is disposed in the cavity with an air gap between the phosphor layer and the metallic wire-grid polarizing layer. A second color light is generated by the first color light. The metallic wire-grid polarizing layer multiply reflects a portion of first color light in plural directions in the cavity to produce secondary excitations. The polarized white light transmits through the metallic wire-grid polarizing layer by mixing a portion of first color light with the second color light excited by the first color light.
The invention discloses a two-dimensional stratified material based SOI (Semicon-on-insulator) base micro loop filter. The two-dimensional stratified material based SOI base micro loop filter comprises an SOI substrate which is formed by a buried oxide layer and top silicon; an SOI micro loop resonant cavity, input straight waveguide and output straight waveguide are arranged on the top silicon and the input straight waveguide and output straight waveguide are arranged on the upper side and the lower side of the SOI micro loop resonant cavity, so that the SOI waveguide structure is formed; two-dimensional stratified materials cover the SOI waveguide structure; two ends of the input straight waveguide are provided with input end optical grating and direct connection optical grating; one end of the output straight waveguide is provided with output end optical grating; areas of the SOI micro loop resonant cavity, which are close to the input straight waveguide and the output straight waveguide, form into a first coupling area and a second coupling area. Compared with the traditional technology, the two-dimensional stratified material based SOI base micro loop filter has the advantages of being narrow in 3dB band width, high in extinction ratio, less in noise, compatible with CMOS technology and widely applied to the on-chip optical interconnection network in the future due to the fact that the SOI base filter is further filtered due to the saturated absorption effect of two-dimensional stratified materials.
The invention discloses a high-linearity degree-of-polarization quantum-well infrareddetector with a plasmon micro-cavity coupled structure. The detector is composed of an upper metalgrating layer, a quantum-well infrared photovoltaic conversion activating layer and a lower metal reflecting layer, wherein the upper metalgrating layer is formed by metal strips. The detector has the advantages that under the mode selection effect of an electromagnetic wave near-field coupled micro cavity formed by plasmonresonance between the upper metal grating layer and the lower metal reflecting layer, photons capable of entering the micro cavity are mainly photons capable of achieving resonance with a detected wavelength polarization mode; the direction of electric vectors of the photons entering the micro cavity is changed to the z direction from the x direction by being modulated in a micro-cavity mode, and the photons can be absorbed by quantum-well sub-bands in a transition mode to achieve the photovoltaic conversion process. With the advantages, the polarization coupled structure can greatly improve the extinction ratio of polarization responses, and extremely-high polarization distinguishing capacity of the detector is achieved.
A method and apparatus for optimizing a non-ideal, real mode converter to substantially achieve the performance of an ideal mode converter. The method consists of optimizing the input linear polarization to the mode converter to balance the power in the principal modes of the mode converter at the output of the mode converter. This has the effect of maximizing the orthogonality of the output polarization states of the mode converter. The present invention also provides an electro-optical mode converter with means to adjust the orientation of the input polarization state to substantially balance the power in the principal modes at the output of the converter. In the case of an intensity modulator, the output polarization state can also be adjusted to maximize mode conversion and extinction ratio.
A broadbandoptical switch with high process tolerance designed and fabricated using Planar Lightwave Circuits (PLC) technology. A 2x2 configuration of the switch is based on a Mach-Zehnder interferometer (MZI) configuration that includes two 3 dB adiabatic couplers and two identical arms. Each adiabatic coupler is characterized by two straight branches having different widths, separated over a coupling length by a changing spacing therebetween and blending in a symmetric intersection area, which connect to two symmetric branches. The two adiabatic couplers are connected by the two arms with their symmetric branches facing each other along an optical propagation axis. Switch control is realized by changing an optical property of one or both of the MZI arms. Implementation in silica-on-silicon PLCs provides switches with an exceptional broadband range (1.2-1.7 mum), very high extinction ratios (>34 dB), low fabrication sensitivity and polarization independent operation.
This invention provides a polarized component with double-metal layer gratings. Multiple parallel dielectriclayers having a period are formed on a transparent base, a groove is set between adjacent dielectriclayers, a first metal layer having a first thickness is formed on the groove, a second metal layer with a second thickness and a width formed on the dielectric layer, in which, a vertical distance of 10~100um is between the first and second metal layers to isolate them. The period is 10~250nm, the thickness is 30~150nm, the first is equal to the second. The proportion of width / period is 25~75%. This invention also discloses the manufacturing method.
The invention discloses a single-ended structure dynamic measuring Brillouin optical fibersensing system and a sensing method. A sensing systemlaserlight source outputs two continuous lights through a first coupler, the first continuous light enters the input end of a modulation high-extinction-ratio module, the modulation high-extinction-ratio module is connected to one input end of a second coupler; the second continuous light enters a phase shift modulating module, the phase shift modulating module is connected to the other input end of the second coupler; the second coupler is connected to the port I of an optical circulator, the port II of the optical circulator is connected with a single-ended module by the sensing optical fiber, the port III of the optical circulator is connected with a de-modulating module. By utilizing the single-ended structure, the BOTDA (Brillouin optical time domain analysis) nominal measuring distance is the effective measuring distance, the problems that the double-ended access is required in the actual measurement and the effective sensing distance is a half of the nominal sensing length existing in the prior art are solved; the extinction ratio of electro-optical modulator is improved, the measuring time is shortened, the monitoring functions of dynamic measurement and long-distance dynamic stress are realized.
The invention discloses a micro-ring resonant cavity electro-optical modulator based on a graphene / molybdenum disulfide heterojunction. The micro-ring resonant cavity electro-optical modulator comprises a substrate layer, a direct-light waveguide, a micro-ring resonant cavitywaveguide and a graphene covering layer. The direct-light waveguide and the micro-ring resonant cavity waveguide are embedded into the substrate layer, and a coupling space is reserved between the direct-light waveguide and the micro-ring resonant cavity waveguide. The upper surface of the micro-ring resonant cavity waveguide is covered with a part of the graphene covering layer. The graphene covering layer comprises a first graphene layer, a second graphene layer, molybdenum disulfide, a first electrode and a second electrode, wherein the first graphene layer and the second graphene layer are isolated by the molybdenum disulfide, the first graphene layer stretches outwards from one side of the micro-ring resonant cavity waveguide and is connected with the first electrode, and the second graphene layer stretches outwards from the other side of the micro-ring resonant cavity waveguide and is connected with the second electrode. The micro-ring resonant cavity electro-optical modulator has extremely low optical loss, a low thermo-optical coefficient, low insertion loss, large environment temperature tolerance, a good modulation depth and a high extinction ratio.