75results about How to "Great modulation depth" patented technology

A method for forming planar-waveguide Bragg grating in a curved waveguide comprises: forming a long chirped planar-waveguide Bragg grating in an Archimedes' spiral such that a long length of the waveguide can fit in a small chip area where the grating is formed in the curved waveguide; using periodic width modulation to form the planar-waveguide Bragg grating on the curved waveguide, and where the formation of the periodic width modulation occurs during the etching of the waveguide core; using rectangular width modulation to create Bragg gratings with a higher order than 1^st order to allow a larger grating period and larger modulation depth, using waveguide width tapering while keeping the width modulation period constant to introduce chirp to the planar-waveguide Bragg grating where the index of refraction is a function of waveguide width, by applying a specific width tapering to create a desired arbitrary chirp profile.

Polarization effects are managed to provide differential timing information for localizing disturbances affecting two or more counter-propagating light signals on one or more optical waveguides passing through a detection zone. Activity can be localized to a point for a security perimeter. Events causing optical disturbance can be mapped to points along a straight line, a perimeter or arbitrary pattern or an array. Events cause local changes in optical properties in the optical waveguide, in particular an optical fiber. Short term local changes are distinguishable from phase changes of light travel in the waveguide by managing the polarization state of input and output beams.

A spatial terahertz wave phase modulator based on the high electron mobility transistor is provided. The phase modulator combines the quick-response high electron mobility transistor with a novel metamaterial resonant structure, so as to rapidly modulate terahertz wave phases in a free space. The phase modulator includes a semiconductor substrate, an HEMT epitaxial layer, a periodical metamaterial resonant structure and a muff-coupling circuit. A concentration of 2-dimensional electron gas in the HEMT epitaxial layer is controlled through loading voltage signals, so as to change an electromagnetic resonation mode of the metamaterial resonant structure, thereby achieving phase modulation of terahertz waves. The phase modulator has a phase modulation depth of over 90 degrees within a large bandwidth, and a maximum phase modulation depth is about 140 degrees. Furthermore, the phase modulator is simple in structure, easy to machine, high in modulation speed, convenient to use, and easy to package.

The invention discloses a generating device for generating an optical frequency comb based on time-frequency mapping and a method for estimating the number of output optical frequency comb lines. Experiment devices are shown as in the picture, and the experimental method specifically comprises the following steps: setting an intensity modulator to have an orthogonal offset and work in a linear offset area, and outputting a flat light pulse after the intensity modulation of continuous lightwaves; and applying chromatic dispersion optical fibers and an optical phase modulator to map the time-domain flat light pulse to a frequency-domain flat optical frequency comb. The obtained number of the optical frequency comb lines can be estimated according to the time-domain width of the flat light pulse and the modulation depth of the phase modulator. Compared with the existing scheme, the scheme is utilized to obtain more accurate time frequency mapping through introducing the chromatic dispersion optical fibers.

The invention discloses a silicon substrate integrated coherent light transmitter chip and a transmitter. The silicon substrate integrated coherent light transmitter chip comprises an optical coupler, a light beam splitter, a light beam combining device, a silicon substrate modulator, a fixed phase drift device and a coupling polarization beam combining device. The optical coupler is used for achieving coupling of input end light. The light beam splitter and the light beam combining device are used for achieving the beam splitting and beam combining functions of optical signals. The silicon substrate modulator is a core modulator part, and is used for achieving the function of loading electrical signals to the optical signals, and generation of modulation signal light is finished. The fixed phase drift device is used for achieving fixed rotating of the phase position of the optical signals. The coupling polarization beam combining device is used for combining two paths of signal light with the transverse electric (TE) polarization state into one path of transverse electric and magnetic field (TEM) signal light. The silicon substrate integrated coherent light transmitter chip and the transmitter are suitable for an optical communication system with multi-phase-position modulating and polarization multiplexing, and have the advantages that cost is low, the CMOS technology is compatible, achieving is easy, integrity is high, and packaging is easy.

The invention belongs to the photoelectronic technical field, and discloses an M-Z electrooptical modulator provided with tunable gratings and based on graphene-molybdenum disulfide heterojunctions. The M-Z electrooptical modulator comprises a substrate layer, the in-out tunable gratings, in-out straight-light waveguides, S-type bent Y-branch waveguides and a two-arm straight light waveguide, wherein the in-out tunable gratings, the in-out straight-light waveguides, the S-type bent Y-branch waveguides and the two-arm straight light waveguide are fully embedded in the substrate layer and successively connected with each other, and the two-arm straight light waveguide is successively provided with a second graphene layer, molybdenum disulfide and a first graphene layer from the bottom up; the second graphene layer is connected to a second electrode mounted between the two arms, and each in-out tunable grating is successively provided with a fourth graphene layer, a boron nitride isolation layer and a third graphene layer while the third and the fourth graphene layers are connected to the a fourth electrode and a fifth electrode respectively. Compared with the prior art, the M-Z electrooptical modulator has the advantages of being small in size, easy to integrate, deep in modulation, high in extinction ratio, big in temperature tolerance and the like.

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 provides a WS ₂ A method for preparing a graphene heterojunction thin film, and a method for building a passively mode-locked fiber laser based on the heterojunction thin film. The method includes: First, a large area of ​​uniform WS ₂ The films were prepared by magnetron sputtering, and then the graphene was transferred to |WS ₂ thin film, forming WS ₂ / graphene heterojunction, and then etched by strong alkali solution to obtain independent WS ₂ /Graphene heterojunction thin film, which can be used as a saturable absorber to generate ultrashort pulse laser when placed in the optical fiber optical system. The present invention innovatively adopts WS ₂ / graphene heterojunction films while overcoming WS ₂ The passive mode-locked pulse width is not narrow enough and the graphene modulation depth is small, so that an ultrashort pulse fiber laser with a large modulation depth can be obtained.

The invention discloses a Schottky gate array type terahertz modulator and a regulation and control method thereof. A periodic gate type metal-semiconductor surface plasmon waveguide structure is adopted, the characteristics of Schottky contact formed by a metal-semiconductor interface and superposition of the Schottky contact and terahertz surface plasmon polariton position are utilized, a positive electrode and a negative electrode are led in and voltage is exerted, so that the terahertz modulation function of the Schottky gate array type terahertz modulator is achieved. The Schottky gate array type terahertz modulator combines a waveguide optical microstructure with a semiconductor electron device together, so that the Schottky gate array type terahertz modulator is well integrated with other electronic components and systems, and the optical functions of terahertz wave transmission and resonance oscillation are achieved. The Schottky gate array type terahertz modulator works from 2.2THz to 3.2THz, the working frequency can be tuned along with the working voltage, the maximum modulation depth is 16dB, and the highest modulation rate is 22MHz. The Schottky gate array type terahertz modulator is an on-chip electronically-controlled high-speed terahertz modulator which is in a small type and can be integrated, and the application requirements for terahertz broadband wireless communications are met.

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.

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 a dark field detection based optical-fiber macrobending coupling structure liquid-level probe. The liquid level sensing principle based on 'CMFTIR (cladding mode frustrated total internal reflection) effect' is proposed for the first time and applied successfully. By means of macrobending, mode field distribution in optical fibers is changed, ratio of cladding mode energy in the optical fibers is increased, and the CMFTIR effect is enhanced; meanwhile, due to macrobending radiation effect, macrobending coupling between the two optical fibers is realized; by means of macrobending coupling, a sensing signal is transferred to a dark field, modulation depth is increased during coupling, higher cladding mode energy ratio can be obtained in the passive optical fiber, and the CMFTIR effect is further enhanced; meanwhile, stability of the coupling structure and consistency of sensors are guaranteed, signal to noise ratio of increased by detection of effectiveness of dark field signals, the liquid-level probe is low in cost and power consumption and high in performance, and discrimination is higher than 4dB.

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.

The embodiment of the invention discloses a terahertz spatial light modulator, a preparation method and application. The terahertz spatial light modulator comprises a first substrate, a second substrate and a liquid crystal layer which are oppositely arranged, and spacer particles are arranged between the first substrate and the second substrate to support the liquid crystal layer; an electrode layer and a first orientation layer are arranged on one side, close to the liquid crystal layer, of the first substrate; the electrode layer comprises a plurality of interdigital electrodes arranged inan array; a super-structure surface layer and a second orientation layer are arranged on one side, close to the liquid crystal layer, of the second substrate; the super-structure surface layer comprises a plurality of split ring resonators which are arranged in an array; the orientation directions of the first orientation layer and the second orientation layer are the same, and the orientation directions intersect with the second direction. According to the technical scheme provided by the embodiment of the invention, the spatial light modulation function can be realized in transmission and reflection modes according to different incident polarization directions, so that the technical problems of single function and low integration level of the terahertz spatial light modulator in the prior art are solved.

MoS prepared by magnetron sputtering ₂ Saturable absorber film and corresponding ultrashort pulse fiber laser, the invention provides a large area uniform MoS ₂ thin film preparation method, and based on the MoS ₂ Passively mode-locked fiber lasers constructed of thin films. The large-area uniform MoS ₂ The film is prepared by magnetron sputtering, and then transferred to the optical fiber optical system as a saturable absorber to generate picosecond-level ultrashort pulse laser. MoS of the present invention ₂ The saturable absorber film is evenly distributed, stable in quality, simple in preparation method, and can be industrialized. Based on the MoS ₂ Ultrashort pulse laser performance of fiber laser with saturable absorber film is stable.