106results about How to "Increase modulation depth" patented technology

The utility model discloses a tunable-frequency Terahertz metamaterials modulator comprising unit devices arranged periodically. Each unit device comprises a substrate, a functional material layer and metal resonator units. The functional material layer is arranged on the substrate, and the metal resonator units are arranged on the functional material layer. When the functional material layer turns to a metal phase from an insulation phase, conductivity of the functional material layer is exponentially increased to increase areas of middle open capacitance of the metal resonator units, the resonator frequency of the metal resonator units is decreased with the increase of the capacitance, so that frequency tuning of the unit devices is realized. By the aid of the tunable-frequency Terahertz metamaterials modulator, the metal opening resonator units arranged periodically are produced on the substrate in the Terahertz wave band of low transmitting consumption, conductivity changes before and after phase changes of the metal insulation phase change materials are used to change areas of the open capacitance of the resonator units, and resonant frequency is tunable; and initiative control of electromagnetic transmission features at a particular frequency by the Terahertz wave band is realized, and large switch ratio or high-modulation depth genera is obtained.

The invention provides a graphene field effect transistor terahertz wave modulator and a manufacture method thereof and aims to increase the modulating speed and depth of the graphene field effect transistor terahertz wave modulator. The graphene field effect transistor terahertz wave modulator comprises a semiconductor substrate, and a medium layer, a graphene film and source and drain electrodes which are arranged on the substrate, and an annular grating electrode which is arranged on the back of the substrate. The terahertz wave modulator is characterized in that the medium layer is an Al2O3 layer, and the thickness ranges from 5 to 100nm; the Al2O3 is deposited by the ALD (atomic layer deposition) method, and the Al2O3 is high in evenness, is free of defects and pores and has better voltage resistance; the leakage current is reduced greatly. The modulating speed of the terahertz wave modulator can be 178 KHz, the corresponded modulating depth is larger than 22%, and the modulating speed and depth are increased significantly; the terahertz wave modulator can be widely applied to the fields of terahertz wave communication systems, terahertz wave detection and terahertz wave imaging.

The invention discloses an electrooptical modulator based on a phase-change material. The electrooptical modulator comprises an SOI substrate; the electrooptical modulator is characterized in that aninput waveguide, a mixing waveguide and an output waveguide connected in sequence are arranged on the SOI substrate in the horizontal direction, the mixing waveguide is formed by laminating a siliconwaveguide layer, a phase-change material GST layer and a copper electrode layer from bottom to top in sequence, the SOI substrate comprises a layer of silicon substrate body with the thickness of 250nanometers and a silicon dioxide layer with the thickness of 2 micrometers, the thicknesses of the input waveguide and the output waveguide are both 250 nanometers, the widths of the input waveguide and the output waveguide are both 400 nanometers, the thickness of the mixing waveguide is 290 nanometers, the width of the mixing waveguide is 400 nanometers, and silicon thin film with the thicknessof 10 nanometers is formed at one side of the silicon waveguide layer through selective erosion. The electrooptical modulator has the advantages that the size is small, on-substrate integration is facilitated, the energy consumption is low, the working bandwidth is large, the modulating depth is large, and the inserting loss is low.

The invention belongs to the field of terahertz imaging technologies, relates to a modulation device in the related field of terahertz imaging, and in particular provides an optical control terahertz wave amplitude modulator based on a silicon nanoneedle. The optical control terahertz wave amplitude modulator comprises a semiconductor laser, an optical fibre, an optical fibre modulator and a terahertz amplitude modulation structure; laser generated by the semiconductor laser enters the optical fibre modulator through optical fibre coupling; the optical control terahertz wave amplitude modulator is characterized in that the terahertz amplitude modulation structure is composed of a silicon-based bottom layer and a silicon nanoneedle tip array on the surface; and the optical fibre modulator outputs modulated laser incident to the surface of the silicon nanoneedle tip array. According to the optical control terahertz wave amplitude modulator disclosed by the invention, a dual-layer structure including the silicon nanoneedle tip array and a high-resistivity silicon/intrinsic silicon layer is adopted; the silicon nanoneedle tip array has the gradient change of a refractive index on the surface of high-resistivity silicon/intrinsic silicon; reflection of terahertz wave and pumping laser can be reduced simultaneously; the insertion loss of the device is obviously reduced; the pumping laser utilization rate is increased; and the device has relatively high modulation depth under relatively low pumping laser power.

The invention discloses a dual-pixel-based device for improving compressed sensing imaging quality of terahertz waves. The device comprises a mask plate capable of achieving transmission and reflection at the same time, and the type of a first terahertz wave detector and the type of a second terahertz wave detector are identical. The terahertz waves carrying imaging object information are modulated through the mask plate, and the mask plate and an imaging object are placed in a light path in parallel; the first terahertz wave detector and the second terahertz wave detector receive terahertz wave radiation transmitted and reflected by the mask plate; radiation intensity arrays received by the first terahertz wave detector and the second terahertz wave detector are correspondingly added and processed, and normalized transmission and reflection radiation intensity arrays are obtained; the normalized transmission and reflection radiation intensity arrays are correspondingly subtracted and processed, and test data for restraining output fluctuation and external disturbance is obtained; a reconstructed image can be obtained by inputting the test data in a compressed sensing recovery program. The influences of external conditions are reduced to the maximum degree at the sampling stage of terahertz wave compressed sensing imaging, and imaging quality is improved.

The invention discloses a terahertz wave rapid modulator based on a coplanar waveguide combining transistor, belongs to the electromagnetic function device technical field, and mainly aims at a rapid dynamic function device of the terahertz wave band; a straight waveguide cavity can introduce terahertz waves; a probe structure can couple the terahertz waves into the core portion transistor combining coplanar waveguide (CPW) structure; the core portion transistor combining coplanar waveguide (CPW) structure comprises a suspension coplanar waveguide formed by three metal wires combining with a semiconductor substrate, and a suspension transistor nested artificial microstructure array added between the coplanar waveguide and an adjacent metal transmission band; the connection/disconnection of the transistor array can be controlled so as to change transmission characteristics of the terahertz wave in the CPW, thus fast modulating the amplitude of the terahertz waves, and the modulated THz can be transmitted by the probe-waveguide structure. The terahertz wave rapid modulator is small in size, simple in processing, and fast in modulation speed.

The invention discloses a manufacture method of a bi-distributed feedback laser double-amplifier based on gamma waveguide, comprising the steps of manufacturing an InP buffer layer, a lower waveguide layer, a multiple quantum well active area, an upper waveguide layer and a grating layer on an N-type indium phosphide substrate in extension and in sequence; manufacturing a passive waveguide area and an active waveguide area on the other side; manufacturing a grating; manufacturing a grating cover layer, a light limitation layer and an electric contact layer on the active waveguide area and on the passive waveguide area in extension and in sequence; etching a gamma-type ridge waveguide downward on the electric contact layer; growing a silicon dioxide insulation layer on the top of the grating and on the surface of the gamma-type ridge waveguide; etching the silicon dioxide insulation layer on the surface of the gamma-type ridge waveguide; manufacturing a first electric isolation groove between the two arms of the gamma-type ridge waveguide on the active waveguide area, and manufacturing a second electric isolation groove between the DFB area and the SOA area on the active waveguide area; manufacturing P electrodes on the two sides of the first electric isolation groove and on the two sides of the second electric isolation groove; reducing the thickness of the N-type indium phosphide substrate; and manufacturing an N-side electrode below the N-type indium phosphide substrate after reducing the thickness to complete the manufacture of the amplifier.

The invention relates to a novel method and a model for improving the modulation depth of a dye doped organic thin film all-optical switch. The method has the following main characteristics that: two linearly polarized light beams which are orthogonal and have a phase difference of 180 degrees are used to excite the switch in an alternating way to speed up a restoration process of the switch, so as to increase the speed and the modulation depth of the switch and increase the speed and modulation depth of the all-optical switch at low exciting power at the same time. The invention also provides a novel all-optical switch model based on the novel method, namely, an orthogonal linearly polarized light excited dye doped organic thin film all-optical switch module. The method has the advantages that: the response speed of the all-optical switch is increased obviously; the modulation depth of the all-optical switch under conditions of a low exciting light power and a high speed switching frequency is obviously improved; and compared with the prior all-optical switch, the orthogonal linearly polarized light excited all-optical switch has a simpler optical path and adjusting method.

A high-speed optical modulator based on Surface Plasmon-Polariton (SPP) at the hetero-junction of a metal-insulator-semiconductor (MIS) tunneling diode and including a phase-matching optical element, such as a prism or gold-lattice structure, is described. An investigation using the coupled mode theory shows that the applied bias across the hetero-junction changes the optical reflectance of an optically coupled MIS tunneling diode, such as a prism-coupled MIS tunneling diode or a gold lattice-coupled MIS tunneling diode, while the modulation efficiency achievable of the device depends on the thickness of the metal film used to construct the tunneling diode.

Period-one nonlinear dynamics of semiconductor lasers are utilized to provide an apparatus for photonic microwave power amplification in radio-over-fiber links through optical modulation depth improvement. The microwave power amplification apparatus includes a microwave-modulated optical signal generation module and a microwave power amplification module. The amplification capability of the present microwave power amplification apparatus covers a broad microwave range, from less than 25 GHz to more than 60 GHz, and a wide gain range, from less than 10 dB to more than 30 dB. The microwave phase quality is mainly preserved while the microwave power is largely amplified, improving the signal-to-noise ratio up to at least 25 dB. The bit-error ratio at 1.25 Gb/s is better than 10⁻⁹ and a sensitivity improvement of up to at least 15 dB is feasible.

The invention provides a Terahertz modulator based on a silicon-based microstructure on SOI, a manufacturing method and a modulation system. The Terahertz modulator successively comprises an Al2O3 substrate of a bottom layer, a SiO2 isolation layer, the silicon-based microstructures, and an Al2O3 passivation layer from bottom to top. The silicon-based microstructures are periodically arranged on the SiO2 isolation layer. Each silicon-based microstructure comprises a two-layer square Si-based step structure. The modulation system comprises a semiconductor laser, a laser modulator, the Terahertzmodulator, a Terahertz radiation source, and a Terahertz detector. In the invention, a reflectivity which is lower than 22% is achieved for a Terahertz wave of 0.4 THz to 0.85 THz and a minimum of 18% can be reached at 0.82 THz so that the reflectivity of a modulation device to the Terahertz wave can be significantly reduced and a utilization rate of the Terahertz wave is improved. A 64.5% modulation depth can be achieved under 808 nm laser radiation with 1200 mw power. Compared with a traditional silicon-based Terahertz modulator, a Terahertz imaging diffusion area can effectively increase aresolution and make the resolution reach above 21.9% in an imaging system.

The invention discloses a channel state selection method and device based on ternary coding. The method includes the steps that a sound source signal is modulated into (2L+1) electric-level-grade quantitative signals x, mapping transformation is performed on the quantitative signals x so that control signals p, m and z can be generated, selection processing is performed on the control signals p, m and z and an M channel feedback signal b, then, an M channel state vector signal y is output, shape-correction processing is performed on the state vector signal y, then, the M channel feedback signal b is generated, and the state vector signal y completes electric-acoustic conversion through a multi-channel power amplifier and an energy converter. The device comprises a modulator module, a mapping module, a selection module, a shape-correction module, the multi-channel digital power amplifier and a loudspeaker array or a multi-voice-coil loudspeaker unit which are all connected in sequence. Through the method and device, hardware resource expenditure can be effectively reduced, hardware electric power consumption can be reduced, system stability is enhanced, the amplitude of an output signal can further be improved, conversion efficiency is improved, and meanwhile high signal-to-noise ratio output capacity is achieved.

The invention discloses an all-optical modulation device based on a micro-nano GaAs optical waveguide. The all-optical modulation device comprises a laser light source, an optical fiber coupler, micro-nano GaAs optical waveguide and a filter, wherein the laser light source, the optical fiber coupler, the micro-nano GaAs optical waveguide and the filter are sequentially connected with one another through optical fibers. All-optical modulation signals realized by applying the all-optical modulation device has higher modulation depth and extinction ratio, the modulation rate reaches as high as dozens of Gb/s, and important performance parameters of modulated signals such as modulation depth and extinction ratio can be flexibly controlled by a pump light intensity adjusting method, a pump light-probe beam frequency detuning method and other methods. The all-optical modulation technology realized by the invention can be used in an integrated optoelectronic technology for effectively reducing the module scale of an optical modulator and improving the modulation rate and the modulation depth.

The invention belongs to the technical field of terahertz wave application, and provides a multi-stage terahertz modulator based on a flexible graphene field effect transistor structure. The multi-stage terahertz modulator is used for overcoming the defects that an existing graphene transistor terahertz modulator is small in modulation depth and only the switch-on state and the switch-off state can be achieved. The terahertz modulator is of an up-and-down-symmetry structure, and comprises a substrate, graphene films, ionic gum, source electrodes, drain electrodes and gate electrodes, wherein the graphene films, the ionic gum, the source electrodes, the drain electrodes and the gate electrodes are symmetrically arranged on the upper surface and the lower surface of the substrate, the graphene films are arranged on the surfaces of the substrate, the source electrodes, the ionic gum and the drain electrodes are arranged on the surfaces of the graphene films, and the gate electrodes are arranged on the surfaces of the ionic gum. According to the terahertz modulator, two flexible graphene field effect transistors are arranged on the two sides of the same flexible substrate, the modulation depth of the modulator can be increased by 37% or above, and meanwhile four-stage modulation of the amplitude of terahertz waves can be achieved through cascade controlling.

The invention discloses an absorption-type optical modulator structure based on an ITO material. The absorption-type optical modulator structure based on the ITO material is high in modulation depth, high in extinction ratio, small in size, low in insertion loss, low in power consumption and high in velocity. The absorption-type optical modulator structure comprises a base layer (1), a first optical wave guide layer (2) which is of a trapezoid structure is arranged on the base layer (1), and an ITO layer (4), a HfO2 isolation layer (5) and a second optical wave guide layer (3) are sequentially arranged on the first optical wave guide layer (2); the absorption-type optical modulator structure based on the ITO material is used for a photon integration and optical fiber communication system.

The invention discloses a THz wave rapid modulator based on a coplanar waveguide combined transistor and belongs to the technical field of electromagnetic functional devices. The THz wave rapid modulator is mainly used for rapid dynamic functional devices at the THz wave band. THz waves are introduced through a straight waveguide cavity; then, the THz waves are coupled to a structure of the core part, namely, a transistor combined coplanar waveguide (CPW) of the modulator through a probe structure, wherein the structure is composed of the suspended coplanar waveguide and a Metamaterials unit and HEMT nested complex structure modulation unit array structure, the suspended coplanar waveguide is formed by combining three metal wires and a semiconductor substrate, and the Metamaterials unit and HEMT nested complex structure modulation unit array structure is added between adjacent metal transmission bands of the coplanar waveguide. The transmission characteristic of the THz waves in the CPW is changed by controlling on-off of modulation units, then rapid amplitude and phase modulation of the THz waves is achieved, and finally the modulated THz waves are transmitted out through the probe-waveguide structure. Effective, efficient and rapid amplitude modulation of the THz waves can be achieved.

The invention provides an optical-control external phase modulator of terahertz space and belongs to the technical field of electromagnetic function devices. The external phase modulator provided by the invention is composed of a semiconductor substrate, an artificial micro structure and a controllable dynamic switch. Through application of external optical induction, an electric conduction rate and a dielectric constant of a switch material are changed. Hence, an electromagnetic resonance mode of the artificial micro structure can be changed and thus phase modulation of terahertz waves can be achieved. The phase modulator provided by the invention has the advantages that a phase modulation depth of over 100 DEG within a large bandwidth and maximum phase modulation capacity of over 150 DEG can be achieved; micro-fabrication techniques can be used for implementation, and the preparation technology is mature and reliable; and a dynamic phase control device which combines a semiconductor material and an artificial microstructure array is achieved, the switch material can be selected from multiple types of high-performance semiconductor materials, multiple control modes can be selected, and the phase modulator has very high practical application values in fields such as terahertz wireless communication, terahertz spectrum technology and terahertz security check imaging.

A method of modulating an optical signal passing through a waveguide structure with a plurality of sections including electrically biasing one or more of the sections with a bias voltage to achieve a predetermined level of chirp, modulation depth, or insertion loss. Preferably, two or more sections are biased with a reverse bias voltage, a zero bias voltage, or forward bias voltage.

The invention discloses a passive mode-locked fiber laser based on a low-mode fiber saturable absorber, and relates to the field of ultra-short fiber lasers. The passive mode-locked fiber laser uses a ring cavity structure and comprises a pump source, a wavelength division multiplexer, a gain fiber, a non-polarization maintaining isolator, a polarization controller, the low-mode fiber saturable absorber and a coupler. The low-mode fiber saturable absorber is composed of an input single-mode fiber, a low-mode fiber and an output single-mode fiber which are fused in turn. The saturable absorption characteristic of the low-mode fiber is based on the nonlinear multi-mode interference effect in the low-mode fiber. The saturable absorber used by the passive mode-locked fiber laser is a real all-fiber saturable absorber and has the advantages of low cost, simple structure and high damage threshold so as to greatly improve the stability of the mode-locked fiber laser and have wide application prospect.

The invention discloses a terahertz multiband modulator based on a high electron mobility transistor, belongs to the technical field of an electromagnetic functional device, especially for a rapid dynamic functional device of a terahertz waveband. The HEMT (High Electron Mobility Transistor) and Metamaterials are combined; the Metamaterials are designed optimally and comprise various complex resonant modes; the high speed dynamic feature of the HEMT and the precise control capacity of the Metamaterials to electromagnetic waves are utilized; the distribution change of two-dimensional electron gas in the HEMT is controlled through an impressed voltage; further the resonant mode conversion of the artificial Metamaterials is controlled; the HEMT terahertz modulator has modulation effects of high modulation depth and high modulation efficiency in modulation frequency bands of four amplitudes; and moreover, the phase modulation depth in a phase modulation frequency band reaches more than 90 degrees.

A waveguide of radio frequency electromagnetic fields is multi-furcated into a plurality of radio frequency waveguide sections, each radio frequency waveguide section having an optoelectronic modulator electrically coupled to it. Each optoelectronic modulator has an optical waveguide disposed therein such that, in use, light traveling in the optical waveguides of the optoelectronic modulators travels in a direction orthogonal with respect to the direction the radio frequency electromagnetic field travels in the radio frequency waveguide sections. The plurality of radio frequency waveguide sections are fed from a common source of said radio frequency energy. In some embodiments, each radio frequency waveguide section has a dielectric material having a length and/or a dielectric constant selected such that a relative time delay of the radio frequency energy propagating in the radio frequency waveguide sections accommodates for a time delay of the light traveling from one optoelectronic modulator to a next optoelectronic modulator of a series connection of multiple optoelectronic modulators.

An optical information recording/reproducing device is provided with a first light source 20a for emitting recording light 22a, a second light source 20b for emitting reproducing light 22b, an objective lens 6 for focusing the emitted lights from the both light sources 20a, 20b on an information recording medium including a recording region 3 capable of three-dimensional recording and photodetectors 19a, 19b for detecting reflected lights 7a′, 7b′ from the information recording medium, and records information on recording layers 1a to 1e utilizing a nonlinear absorption phenomenon. At the objective lens 6, an average rim intensity of the recording light 7a is lower than that of the reproducing light 7b.