33results about How to "Flexible tuning" patented technology

The invention relates to a femtosecond laser programmed type pixel-level long-period fiber grating manufacturing device. A designed programmed type control system realizes the writing of femtosecond laser to long-period fiber grating fixed on optical fiber of a high-precision three-dimensional displacement platform, and the manufactured long-period fiber grating has uniform modulated refractive index, the writing of the long-period fiber grating with tunable resonant wavelength and resonant peak can be realized by controlling the mobile distance and reciprocating times of the three-dimensional displacement platform, and the femtosecond laser programmed type pixel-level long-period fiber grating manufacturing device has the characteristics of small writing loss and high femtosecond laser utilization rate. Through the design of the programmed type system, the writing of the long-period fiber grating with tunable resonant wavelength and resonant peak can be realized by utilizing femtosecond. The manufactured femtosecond laser programmed type pixel-level long-period fiber grating manufacturing device has the advantages of low noise, no backward reflection, long resonant wavelength, easiness in tuning, controllability on the depth of resonant peak, and the like, thus providing an efficient preparation method with tunable parameters for applications in the fields of scientific research, fiber-optical communication and optical fiber sensing technology.

The invention discloses a reconfigurable single-band-pass microwave photon filtering system and method and belongs to the technical field of microwave photons. A device comprises a laser, an optical divider, an electro-optic phase modulator, an optical isolator, a first polarization controller, a high-nonlinearity medium, a pumping microwave source, an electro-optic intensity modulator, an optical amplifier, a second polarization controller, an optical circulator and a photoelectric detector. According to the microwave photon filtering system, single-band-pass photon filtering is conducted by utilizing a stimulated brillouin scattering effect in the high-nonlinearity medium, and a function of filtering reconfiguration is achieved by controlling the frequency spectrum of pumping microwave. The system and method solves the problem that the existing periodical microwave photon filtering system is limited in filtering range and the filtering waveform is not easy to reconfigure, and has the advantages of being high in stability and convenient to operate.

The invention relates to the technical field of communication, and particularly relates to an antenna and a mobile terminal. The antenna comprises a system ground, a closed metal ring and a main board electrically connected with the system ground; the metal ring is electrically connected with the system ground; a radiation body is formed on the part, from a first position to a second position, on the metal ring; the main board is provided with a grounding circuit, a first tuning switch, a second tuning switch, a feeder circuit and an impedance matching circuit; the grounding circuit is electrically connected with a first grounding point, and electrically connected with the metal ring in the third position of the metal ring; the first tuning switch is electrically connected between the first grounding point and the grounding circuit; the second tuning switch is electrically connected between a second grounding point and the fourth position of the metal ring; the feeder circuit is electrically connected with a feeding point, and electrically connected with the metal ring in the fifth position of the metal ring; and the impedance matching circuit is electrically connected between the feeding point and the feeder circuit.

The invention discloses a chirp microwave pulse signal generation method and device based on an electro-optic external modulation nonlinear effect. Under a large signal modulation mode, single-wave-length-light carrier waves are subjected to phase modulation with a large modulation depth in an electro-optic modulator; relative phase shift or malposition are introduced into phase modulation signals through a dimmable delaying module, after nonlinear frequency chirp zone selecting is achieved through a time domain switch, the signals are input to an photoelectric converter for beat frequency, and microwave pulse signals with adjustable pulse speed, pulse and center carrier frequency are obtained. The method and device have the photonics advantages of being high in frequency, large in instant bandwidth and the like, and have the advantages of being high in signal parameter accuracy, easy to tune, relatively simple in structure, wide in application prospect and the like.

The invention provides a tunable active filter which comprises a light polarization input control unit, a magnetic filter body and a magnetic field loading unit, wherein the light polarization input control unit is used for converting input light into TM-mode polarized light which incomes in the K direction, the magnetic filter body is arranged at the rear end of an optical path of the light polarization input control unit and prepared through magnetic materials and dielectric substances, the magnetic filter body is of a periodic Bragg structure which has defects, extends in the K direction and is used for filtering the polarized light which incomes from the light polarized input control unit by means of a transmission peak generated by the defects of the periodic Bragg structure, and the magnetic loading unit is used for generating a magnetic field which is perpendicular to the K direction and the incident polarized light electric field direction and modulating the position of the transmission peak generated by the defects of the Bragg structure. The tunable active filter is easy to manufacture, quick in response, flexible in tuning process and high in tuning precision.

The invention discloses a broadband continuous tuning optical carrier microwave filtering device, which comprises spectral hole-burning crystal, a low-temperature thermostat, an electrooptical modulator, a carrier wave laser, an optical fiber collimator, a frequency accurate-tuning laser, an arbitrary signal generator, a converging lens and an extender lens, wherein the frequency accurate-tuning laser emits a hole-burning preset laser light to irradiate the crystal; ions with a corresponding frequency are excited to an upper energy level; within the lifetime of the upper energy level, a spectral burnt hole with a corresponding laser light frequency is left in the crystal; a microwave signal is loaded to a carrier wave laser light through the electrooptical modulator; and when to-be-filtered optical carrier microwave signals irradiate the same position of the crystal, the optical carrier microwave signal with the corresponding spectral hole-burning frequency passes through the crystal and the signals with other frequencies are absorbed by the crystal, so that reconfigurable and tunable optical carrier microwave signal filtering is achieved. The broadband continuous tuning optical carrier microwave filtering device has the characteristics of being flexible, tunable, reconfigurable and the like within a broad frequency range on the basis of transient spectral hole burning; and the single-passband frequency response is easy to achieve.

The invention provides a broadband rectifying antenna with adjustable matching based on a resonant structure, including a receiving antenna and a rectifying circuit based on an adjustable branch of a resonant structure; the rectifying circuit is sequentially composed of a front capacitor, a rectifying topology, a matching circuit, Output filter and load; the resonant structure and the matching branch are inserted in series between the precapacitor and the rectification topology; through the impedance change of the resonant structure at different frequencies, the impedance of the matching branch is adjusted, thereby adjusting the rectification circuit in the entire broadband. The impedance at a frequency includes the real and imaginary parts of the rectifier circuit impedance. The invention adopts the series-parallel resonance structure of inductance and capacitance, and simulates the closed or disconnected state of the adjustable switching device and the impedance adjustable characteristic of the varactor adjustable diode as the frequency changes, and converts the matching branch into an adjustable matching branch, so that the rectifier circuit The impedance is changed as the frequency changes, and a good impedance conjugate matching with the receiving antenna is realized adaptively.

The invention provides a graphene and nano antenna array-based tunable directional coupler, which comprises a nano antenna array, a first graphene layer and a waveguide, wherein the nano antenna arrayis arranged on the upper surface of the first graphene layer; the first graphene layer is arranged above the waveguide; the nano antenna array is used for highly and directionally coupling an opticalsignal component meeting a preset polarization direction in free space and in a tunable directional coupler working band to a specific mode in the waveguide; and the first graphene layer is used forchanging the working wavelength of the tunable directional coupler under effects of external voltage. According to the graphene and nano antenna array-based tunable directional coupler provided in theinvention, as the first graphene layer is used for changing the working wavelength of the tunable directional coupler under effects of external voltage, high-speed and real-time tuning on the workingwavelength of the tunable directional coupler can be realized.