33results about How to "Changing the resonance wavelength" patented technology

The invention belongs to the field of microwave photonics, and discloses a system and method for frequency tunable microwave phase shifting. The method comprises the following steps that after a continuous light carrier is splitted, one beam of the continuous light carrier is processed by a MZ Mach-zehnder, and double-sideband optical signals restrained by the carrier are produced; the other beam of the continuous light carrier is processed by a phase modulator, and phase-shifted light carrier signals are produced; two beams of light signals are combined in a wave mode, one one-step sideband is removed through a tunable micro-ring filter in a filtering mode, a frequency-moved carrier signal and a phase-shifted carrier signal are obtained, photovoltaic conversion is carried out through a photoelectric detector, and a phase shift microwave electrical signal is produced; the resonant frequency of the tunable micro-ring filter is equal to any one-step sideband of the two one-step sidebands output by the MZ Mach-zehnder by changing the frequency of an input voltage drive signal and the resonant wavelength of the tunable micro-ring filter, and the frequency of the phase shift microwave signal is changed. The system and method for the frequency tunable microwave phase shifting is stable in output performance, fast in phase shift adjusting response, small in output microwave range fluctuation and continuously adjustable in wide frequency range.

The invention relates to a surface nano grating-based wavelength tunable vertical cavity surface emitting laser and a preparation method, which belong to the field of semiconductor photoelectronic devices. The laser has an inner cavity contact laminated structure; a positive electrode layer (1) is arranged on a P-type ohmic contact layer (5); an air-gap layer (12), a gallium arsenide layer (2a), and a gallium aluminum arsenide layer (2b) are arranged above the ohmic contact layer (5) in turn; a gallium aluminum arsenide oxidation current limitation layer (6), an active region (7), an n-type gallium aluminum arsenide layer (8a), an n-type gallium arsenide (8b), an n-type gallium arsenide substrate (10), and a substrate electrode layer (11) are formed below the ohmic contact layer (5) in turn; and a nano grating (15) is positioned on the surface of the gallium arsenide layer (2a). The thickness of the air-gas layer can be subjected to mechanical adjustment of an electrostatic force and the like, so that photon phase change can be transmitted in the resonant cavity of a laser and an outputted light beam passes through the nano grating (15) immediately; therefore, a wavelength and polarization can be simultaneously controlled.

The invention discloses a microwave photonic band stop filter based on a Microring-Mach Zehnder interference (MR-MZI) structure, which comprises a semiconductor laser, a polarization controller, a phase modulator, an optical band pass filter, an MR-MZI integrated optical filter unit and a photoelectric detector. Narrow bandwidth filter is realized through adjusting the coupling interval between microring resonators in the MR-MZI integrated optical filter unit; through adjusting the bias voltage of each heating electrode in the MR-MZI integrated optical filter unit, the amplitude and the phase of signals are regulated; the amplitude response and the phase response of the microring are used for being combined with the MZI structure in the MR-MZI integrated optical filter unit to generate fully destructive interference, and an ultra high inhibition ratio is realized. According to the microwave photonic band stop filter provided by the invention, on the basis of the narrow bandwidth, the ultra high inhibition ratio is realized, and the microwave photonic band stop filter performance is improved.

The present invention provides a Fabry-Perot cavity filter for dynamic color control and a preparation method and a tuning method, which sequentially include a first metal thin film layer, a second non-conductive dielectric layer, a third A transparent conductive oxide layer, a fourth metal layer, and a fifth substrate layer; the second layer of non-conductive dielectric layer acts as a barrier layer to block the migration of metal ions after electrochemical metallization of materials with a dielectric constant that tends to 0 The third layer of transparent conductive oxide layer is a material with a dielectric constant close to 0, which can realize the change of the refractive index under the action of an electric field, thereby adjusting the refractive index of the Fabry-Perot cavity; the present invention is based on The ECM effect changes the effective refractive index of the ENZ material, thereby changing the resonance wavelength of the FP cavity, which can effectively solve the above problems, and can complete the memory of the resonance condition while removing the voltage.

The invention discloses a 2*2 long period fiber Bragg grating coupler which comprises a force applying device, and two pieces of closely contacted and parallel arranged bare optical fibers without protective layers, namely, transmission fiber and coupling fiber. The force applying device periodically applies radial pressure with period Lambada being hundred-micron magnitude on the axial propagation of the optical fibers, thus gratings with equivalent spatial variation are written on the axial propagation of the bare optical fibers. When spatial period of fiber Bragg grating causes fiber core fundamental modes and higher order cladding modes to satisfy the phase position matching condition, the fiber core fundamental modes and the cladding modes of the transmission fiber and the coupling fiber perform intercoupling; besides, cladding modes of the transmission fiber and the coupling fiber perform intercoupling under action of evanescent field. Based on the couplings, periodical radial pressure plays the role of a coupler on the two pieces of bare optical fibers. As the long period fiber Bragg grating is only generated by external force, the long period fiber Bragg grating coupler is a wavelength choice direction coupler easy to write and erase, and can be applied to optical communication network as a flexible add / drop multiplexer and the like.

The invention discloses a multi-layer wrapped quantum dot core-shell composite particle and a preparation method of the core-shell composite particle. The preparation method comprises wrapping a transparent inorganic insulating layer on the surface of a quantum dot to obtain an inorganic insulating layer wrapped quantum dot; connecting the inorganic insulating layer with a reductive group and performing surface modification to obtain a surface activated inorganic insulating layer wrapped quantum dot; and wrapping a precious-metal nano-particle layer on the surface of the surface activated inorganic insulating layer wrapped quantum dot to obtain the multi-layer wrapped quantum dot core-shell composite particle. The multi-layer wrapped quantum dot core-shell composite particle has characteristics of good stability, low biological toxicity, strong fluorescence intensity and high quantum efficiency. The reaction for preparing the multi-layer wrapped quantum dot core-shell composite particle is performed in a solution; high temperature and high pressure are not needed during the whole process; the operation is simple; the yield is high; a large number of multi-layer wrapped quantum dot core-shell composite particles can be prepared at a time; wrapping layers with different thickness can be obtained by controlling the reaction conditions and reaction parameters; and thus the multi-layer wrapped quantum dot core-shell composite particle has a good application prospect.