41results about How to "Lower effective refractive index" patented technology

An optical fiber suitable to support single mode optical transmission at longer wavelengths (e.g., 1550 nm) is formed to comprise a pure silica core region and a “down doped” cladding layer. The core region is defined as having a diameter d and the cladding layer is defined has having an outer diameter D. In accordance with the present invention, single mode propagation will be supported when D/d>8.5, and is preferably in the range of 9–10.

The invention relates to the technical fields of surface plasmon optical waveguide structures and provides an antisymmetric-high energy mode surface plasmon optical waveguide structure capable of low-loss transmission for overcoming a large loss drawback of the conventional metal/media/metal waveguide transmission. The optical waveguide structure realizes a waveguide structure for supporting transmission in an antisymmetric-high energy mode by combining the refractive index difference between a plurality of high refractive index layers and a low refractive index substrate and a low refractive index covering layer and a surface plasmon effect of a metal layer and uses the low refractive index medium layers on two sides of the metal layer to reduce transmission loss, thereby realizing low-loss surface plasmon optical waveguide. Meanwhile, the optical waveguide structure has the advantages of small effective mode filed area and low loss can be used for manufacturing optical devices of a subwavelength size and ultra high integration level optical circuits.

The invention discloses a compact adjustable multi-mode interfering coupler that includes input channel connecting to optical signal input end, multi-mode wave guide, modulating module, and output channel connecting to the output end of optical signal. The feature is that: the multi-mode wave guide is not rectangle, and input channel and output channel connecting to the two sides of the multi-mode wave guide along optical signal transferring direction, and the modulation module is set on the surface of multi-mode wave guide. The invention decreases the bat length of multi-mode wave guide and makes component compact. It could be used in the wave guide type coupler of optical communication system, optical computer system and photon/ photoelectron integrated loop.

A novel high-sensitivity photonic crystal fiber terahertz evanescent wave sensing device is a fiber core cladding structure and comprises a fiber core and a cladding, a high-density polyethylene material is used as a substrate, the fiber core consists of a doped core and six small air holes uniformly distributed on the periphery of the doped core, large air holes which are axially arrayed in a regular-triangularly periodically manner are disposed on the peripheries of the six small air holes of the fiber core, and the large air holes and the substrates around the large air holes form the cladding. The novel high-sensitivity photonic crystal fiber terahertz evanescent wave sensing device has the advantages that the fiber core of a solid photonic crystal fiber is provided with the doped core, and the six small air holes are additionally disposed on the periphery of the fiber core, so that the sensitivity of the photonic crystal fiber terahertz evanescent wave sensing device is obviously improved; and the doped core with a low refractivity is beneficial for reducing the effective refractivity of a fundamental mode and reducing the effective refractivity difference of the fiber core and the cladding, the sensitivity of the sensing device can also be enhanced, and the evanescent wave sensing device has a high application value in terms of detection for gas, toxic biochemical preparation, food safety, air pollution and the like.

The invention discloses a solid-core polarization-maintaining cut-off-free single-mode microstructure optical fiber and a preparation process thereof. The solid-core polarization-maintaining cut-off-free single-mode microstructure optical fiber comprises an outer cladding layer of an annular solid structure, an inner cladding layer with periodically distributed air holes and a solid fiber core positioned in the geometric center of the optical fiber which are sequentially distributed from outside to inside, wherein the inner cladding comprises a plurality of circles of air holes; central connecting lines of each circle of air holes in the radial section form a regular hexagon; one of the air holes in the innermost ring or two or three continuous air holes which are symmetrically distributedis/are defined as a first air hole or first air holes; the rest air holes are defined as second air holes, the hole diameter of the first air hole/holes is smaller than that of the second air holes,and a ratio of the hole diameter of the second air holes to a distance between the centers of every two adjacent air holes is smaller than 0.42. The solid-core polarization-maintaining cut-off-free single-mode microstructure optical fiber has advantages that the optical fiber supports a cut-off-free single mode, has a large mode field area, is adjustable in dispersion, can transmit polarized lightand birefringence, is simple in preparation, does not need to be doped with a silicate glass stress rod, can maintain an optical fiber microstructure, is low in preparation cost, and is high in preparation yield.

The invention discloses an LNOI spot size converter based on a sub-wavelength grating. The LNOI spot size converter comprises a top layer conical waveguide, a bottom layer conical waveguide, a conical sub-wavelength grating, a SiO2 inverted conical thick ridge waveguide cladding, a SiN sub-wavelength grating thin layer and an optical fiber fixing groove. A preparation method of the LNOI spot size converter comprises the following steps of preparation of the top layer conical waveguide and the bottom layer conical waveguide, preparation of the conical sub-wavelength grating, preparation of the SiO2 inverted conical thick-ridge waveguide, preparation of the SiN sub-wavelength grating and preparation of the optical fiber fixing groove. The structure that the double-layer conical waveguide is combined with the conical sub-wavelength grating, the SiN sub-wavelength grating and the SiO2 inverted conical thick ridge waveguide is adopted, the function of amplifying a small-size optical mode field in the LNOI optical waveguide is achieved by adjusting the effective refractive index of the waveguide core layer and the effective refractive index of the cladding, and then the coupling efficiency of the LNOI optical waveguide and the single-mode optical fiber is improved.

The invention provides a preparation method of a light emitting diode with photonic crystals with gradually-changed radiuses, comprising the following steps of: obtaining a gallium nitride based light emitting diode epitaxial wafer; growing an ITO (Indium Tin Oxide) layer on a P-type GaN contact layer of the epitaxial wafer; depositing a SiO2 layer on the ITO layer; manufacturing a mask plate graph on the SiO2 layer; etching according to the mask plate graph to remove one part of the SiO2 layer, the P-type GaN contact layer, an active layer and an N-type GaN contact layer at one side of the epitaxial wafer; etching until the depth is in the N-type GaN contact layer; etching downwards and manufacturing a first photonic crystal layer structure on the ITO layer, and etching downwards and manufacturing a second photonic crystal layer structure on the basis of the first photonic crystal layer structure, wherein the second photonic crystal layer structure is the same as the first photonic crystal layer structure in a lattice constant; manufacturing an N-electrode on a tabletop formed at one side of the GaN contact layer; and manufacturing a P-electrode at one side of the first photonic crystal layer structure on the ITO layer to finish the manufacturing of a device. According to the preparation method disclosed by the invention, the light extraction efficiency of the light emitting diode is improved.

The invention discloses a terahertz polarization beam splitter. The terahertz polarization beam splitter comprises three rectangular medium strips and a medium circular tube. The beam splitter is characterized in that a first rectangular medium strip is fixed on an inner wall of the medium circular tube via a central axis of the medium circular tube; a second rectangular medium strip and a third rectangular medium strip are vertical to the first rectangular medium strip respectively and are fixed on the inner wall of the medium circular tube; the second rectangular medium strip and the third rectangular medium strip are symmetrically distributed on two sides of the first rectangular medium strip; an intersecting portion of the first rectangular medium strip, the second rectangular medium strip and the third rectangular medium strip is two fiber cores. The size of each fiber core is less than an operating wavelength. Fiber core conduction mode energy can be mostly distributed in air so that material absorption losses are reduced. Besides, a fiber core conduction mode is effectively restricted around the fiber cores by a fiber cladding; changes of a surrounding environment of the polarization beam splitter do not influence polarization beam splitter performance so that operation is convenient.

The invention supplies an anti-reflection coating compound, the film and the manufacture method. It has an initialization agent and an oxide containing gel containing a gel particle with polymizable function radical. The film is formed by the gel particle and has plural nanometer hole. It could induce FI containing function radical and sharply decrease the effective refractive index below 1.45 to make the reflection ratio below 3%. The anti-reflection film has excellent mechanical strength and rigidity.

The invention relates to a 3D nano-porous film and the manufacturing method thereof. And the manufacturing method comprises: (a) providing a substrate, which has a precoating surface; (b) forming a film layer composed of 3D nano porous coating combination on the precoating surface; (c) supplying energy to the film layer to making polymerization reaction on the above combination so as to form organic-inorganic mixed layer on the precoating surface; and (d) dissolving out template from the mixed layer by second solvent to form the 3D nano porous film, which has effective refractive index below 1.45 and reflectivity not greater than 3%, and extremely good mechanical strength and rigidity, completely suitable to be used as antireflective and wearable coating for a display unit.

The invention discloses a silicon-based tunable laser based on a mode converter and an implementation method thereof. The silicon-based tunable laser comprises a semiconductor amplifier, a silicon-on-insulator (SOI) wafer, a coupler, a TE0 mode waveguide, the mode converter, a first sampling optical grating and a second sampling optical grating, wherein the coupler, the TE0 mode waveguide, the mode converter, the first sampling optical grating and the second sampling optical grating are sequentially connected with the SOI wafer, the first sampling optical grating and the second sampling optical grating are connected at intervals, the coupler is used for transmitting an optical field output from the semiconductor amplifier to the TE0 mode waveguide to obtain a TE0 mode optical field, the mode converter is used for converting the TE0 mode optical field to a new mode optical field with effective refractive index smaller than that of a TE0 mode, and the first sampling optical grating and the second sampling optical grating are used for reflecting the new mode optical field to the semiconductor amplifier. By the silicon-based tunable laser, more precision processing means is not needed, the process cost is greatly reduced, and the process stability is higher; and meanwhile, the first sampling optical grating and the second sampling optical grating are arranged on the same waveguide, an optical divider can be omitted, and the complexity is reduced.

The invention relates to the technical field of optical fiber communication, and discloses a double-layer weak-coupling few-mode hollow anti-resonance optical fiber which comprises an outer wrapping area and a fiber core area. The fiber core area is arranged in the outer wrapping area, and the fiber core area and the outer wrapping area are concentric circles; the outer wrapping area comprises an outer wrapping layer, a plurality of second-layer nested tubes and a plurality of first-layer anti-resonance tubes; the second-layer nested tubes are internally tangent to the outer wrapping layer; the first-layer anti-resonance tubes are located between the second-layer nested tubes and the fiber core area and are tangent to the second-layer nested tubes and the fiber core area respectively; the plurality of second-layer nested tubes are uniformly and circumferentially distributed at equal intervals and surround the fiber core area; and the plurality of first-layer anti-resonance tubes are arranged at equal intervals, are uniformly and circumferentially distributed and surround the fiber core area. The problems that an existing optical fiber lacks flexible optimization capacity and does not support few-mode weak coupling transmission, and the limited loss of a transmission mode is large are solved.

A traveling wave optical modulator in which occurrence of jitter is suppressed when it is driven through a driver, and its regulating method; especially in which the degree of freedom is enlarged in the combination of the driver and the traveling wave optical modulator and jitter can be suppressed effectively even after they are combined, and its regulating method. The traveling wave optical modulator comprises a substrate exhibiting electrooptic effect, an optical waveguide formed on the substrate, and a modulation electrode performing modulation control on a light wave propagating through the optical waveguide, characterized in that the traveling wave optical modulator is connected with a driver performing drive control thereof, and the frequency characteristics (b) of electrooptic conversion response of the traveling wave optical modulator is regulated to correct the frequency characteristics (a) of gain of the driver. Preferably, regulation of the frequency characteristics of electrooptic conversion response is characterized by the regulation of at least one of the impedance of the modulation electrode or the impedance of a termination resistor.