45results about How to "Reduced Line Width Requirements" patented technology

The invention discloses a multi-sub-block phase noise estimation compensation method suitable for a CO-OFDM system. The method comprises the steps that each CO-OFDM symbol is divided into a plurality of sub-block symbols, so that light-phase noise of each sub-block symbol is estimated and the estimation accuracy and temporal resolution of the light-phase noise are improved. Meanwhile, signals obtained after channel balance is conducted are selected to serve as input of divided blocks, no complex crosstalk compensation algorithm among the residue symbols is needed in the sub-block phase noise estimation process, and the complexity of the algorithm is lowered. The method is high in practicability, the requirement for the line width of a laser light source of the CO-OFDM system can be effectively lowered, and the method has a great significance to application of the CO-OFDM system in a high-speed optical fiber communication network of the next generation.

The embodiment of the invention discloses a method and a device for generating and receiving an OOFDM (Orthogonal Frequency Division Multiplexing) signal and a wavelength division multiplexing system, belonging to the communication field, wherein the method for generating the OOFDM signal comprises the steps of: converting one path of serial high-speed data into N paths of parallel low-speed data; respectively modulating and mapping the N paths of parallel low-speed data to obtain N paths of information sequences; expanding the N paths of information sequences into 2N+2 paths of information sequences with Hermitian symmetrical structures; carrying out rapid inverse Fourier conversion on the 2N+2 paths of information sequences to obtain an OFDM baseband signal; carrying out digital-to-analogue conversion on the OFDM baseband signal to obtain an OFDM analog signal; and modulating the OFDM analog signal to an optical carrier wave to obtain the OOFDM signal. The OOFDM signal generated in the embodiment of the invention is received without tracking and compensating phase and frequency with a complex algorithm, therefore, the cost of realizing the system is lowered.

The invention provides a balanced photoelectric detection method and system capable of eliminating beat interference between signals. Light carrier waves and light OFDM signals in received SSB-OOFDM signals are separated during a partial wave period, the light carrier waves and the light OFDM signals are coupled again through a 3dB 2*2 optical coupler, appropriate dependency is introduced between the light carrier waves and the light OFDM signals, photoelectric balanced detection is conducted on the coupling output, the two paths of signals are converted into electrical signals and are subtracted in the electric field to obtain output electric OFDM signals, the electric signals only have OFDM radio-frequency signal parts, and no SSBI interference is introduced. According to the balanced photoelectric detection method and system capable of eliminating beat interference between the signals, receiving of SSBI and direct current components can be achieved, the necessity of setting frequency band protective intervals due to the SSBI is theoretically eliminated, and the frequency spectrum utilization efficiency of a SSB-OOFDM system can be improved.

The invention discloses a method for self-coherence detection of an optical carrier radio frequency link based on polarization multiplexing. The invention relates to the technical field of optical communication and microwaves. The method is shown in the attached drawing, and comprises a laser source, a vector signal source, a polarization controller, a polarization beam splitter, a polarization multiplexing Mach-Zehnder modulator, a single-mode fiber, an erbium-doped fiber amplifier, a 90-degree optical coupler and a balance photoelectric detector. According to the method, two paths of different radio frequency electric signals are used for respectively carrying out intensity modulation and phase modulation on two optical carriers with orthogonal polarization states in a polarization multiplexing Mach-Zehnder modulator; frequency mixing is carried out through a 90-degree optical coupler; signal processing is performed on the electric signal output by the balance photoelectric detectorto recover an original electric signal; the polarization multiplexing mode is used for improving the utilization rate of spectrum and light source power; self-coherent detection is used at the receiving end; and a local oscillation light source and a complex phase noise elimination algorithm are avoided, so that the system cost is reduced, and the requirement for the line width of the laser is lowered.

The invention discloses a coherent passive optical network system and signal transmitting and receiving method, and relates to an optical access network. The method includes the following steps that in the downlink direction, k multi-carrier signal transmitting-receiving devices in an OLT have high-speed DACs, each multi-carrier signal transmitting-receiving device generates N downlink digital signals in a digital method, the k multi-carrier signal transmitting-receiving devices and a wavelength division multiplexing and demultiplexer of one k path are combined to generate dense or super-dense wavelength division multiplexing signals, the dense or super-dense wavelength division multiplexing signals are selective received by a coherent ONU after passing a power distributor, and the coherent ONU achieves selection of channels by adjusting LO wavelength in coherent detection. The coherent passive optical network system is low in cost, simple in structure, high in sensitivity and suitable for a super-dense wavelength division multiplexing network.

The method involves transmitting an electromagnetic radiation e.g. laser light, to a target object and receiving the radiation dispersed back by the object and guided over a reference length. The radiation is converted into signals, where tuning characteristics and phase noise of the light are characterized in a reference interferometer. A distance of the object is determined from the signals and under the usage of the length. Independent claims are also included for the following: (1) a computer program product with program code for executing a method for measuring absolute distance of a target object (2) a device for executing a method for measuring absolute distance of a target object.

The invention discloses a homodyne detection type coherent light transmission system. The homodyne detection type coherent light transmission system comprises a semiconductor laser light source, a first polarized light control device which enables an angle of 45 degrees to be formed between a polarization direction of a laser and an X-axis in an end face of a photoelectric modulator, the photoelectric modulator which modulates same-phase and orthogonal electric signal components to the laser, a second polarization control device which enables an angle of 45 degrees to be formed between the polarization direction of the X-axis light component of a first light beam and a main axis of a first polarizer i and enables an angle of 45 degrees to be formed between a polarization direction of an X-axis light component of a second light beam and a main axis direction of a second polarizer j, a light beam splitter which splits the laser into the first light beam and the second light beam, a quarter-wave plate which enlarges a phase difference between the X-axis component and a Y-axis light component in the first light beam by pi/2, the first/second polarizer which filters away a projection component of the first/second light beam on the main axis of the first/second polarizer i, and a first photoelectric detector, a second photoelectric detector and a baseband signal processing module all of which are used for signal demodulation.

The traditional backscatter-base distributed fiber-optic vibration sensing technology (PDVS), as shown in chart 1, comprises a pulse light source 1; the traditional scheme only has one sensing optic cable (as shown in chart 1) and the interference actually occurs in the sensing optic cable. A backscatter-based distributed fiber-optic vibration sensing system comprises a light path system and a data processing system, wherein the light path system comprises a pulse light source, one end of which is connected with one end of a 2*2 coupler; the 2*2 coupler is connected with a sensing optic cableand a reference optic cable. According to the invention, the interference is transferred from the sensing optic cable to the coupler so as to limit the optic path difference of an interference signalin the technological error range of the coupler and reduce the requirement of the system for the line width of the light source.

The invention provides a fiber laser asymmetric compensation spectral synthesizing device, which comprises a fiber laser array, a converging lens and two diffraction gratings. The fiber laser array, arranged in parallel, uses the converging lens to collimate the outgoing laser beams and relies on the two diffraction gratings with different linear densities to compensate the angular deflection of the converging lens to different wavelength laser beams. The invention has the advantages of low requirement for the laser line width and the diffraction grating damage threshold, of a strong ability to expand the number of channels and of producing high quality beams. With the device, it is possible to greatly enhance the brightness of the outputted laser from a spectral synthesizing system.

The invention provides an electrode assembly, an electrophysiological catheter and an electrophysiological system. The electrode assembly comprises an electrode main body, a sub-electrode assembly and an electric transmission line, wherein the sub-electrode assembly and the electric transmission line are arranged on the electrode main body; the electric transmission line comprises a plurality of ablation lines; the sub-electrode assembly comprises a plurality of first ablation electrodes and a plurality of second ablation electrodes; each ablation line comprises a transmission main line, a first transmission branch line and a second transmission branch line; the first ablation electrodes and the second ablation electrodes are electrically connected with the output ends of the corresponding first transmission branch lines and the output ends of the corresponding second transmission branch lines respectively; and the input ends of the first transmission branch lines and the input ends of the second transmission branch lines are intersected at the transmission main lines. The transmission branch lines of different ablation electrodes are arranged in a parallel manner, so that the resistance value of the ablation lines is reduced, the current resistance of the ablation lines is improved, meanwhile, the ablation boundary of the catheter is also improved, and the ablation depth is increased.

The invention discloses a sliding window-based estimation compensation method for a CO-OFDM optical phase noise. The method comprises the following steps of: estimating the common phase noise of each CO-OFDM symbol and completing compensation in a frequency domain, then judging, and carrying out IFFT transform on the judged signal to obtain a hypothetical 'transmitting end' time-domain signal; estimating an optical phase noise time-domain value in each CO-OFDM symbol by virtue of the hypothetical 'transmitting end' time-domain signal and a 'receiving end' time-domain signal polluted by an optical phase noise, then carrying out moving average processing on the optical phase noise of each time-domain sample, finally carrying out optical phase noise compensation processing on each CO-OFDM symbol in time domain. The method is capable of tracking the change conditions of the optical phase noises, and improving the accuracy of optical phase noise estimation and the performance of the whole optical communication system, high in practicability, and capable of effectively lowering the requirements of a CO-OFDM system on the line width of a laser light source, as well as has important significance in applications in the next generation of high-speed optical communication networks.

The invention discloses a coherent optical module and an optical communication system, and relates to the technical field of communication, the optical module comprises: a sending end, wherein a first optical splitter divides the output of a laser into one path of local oscillation light and N paths of optical carriers with equal power, the local oscillation light is sent out through a first circulator after coarse tuning, each coherent optical transmitter receives a group of modulated four-path electric signals, modulates the modulated four-path electric signals and one path of optical carrier into polarization multiplexing signal light, and transmits the polarization multiplexing signal light through a second circulator; and a receiving end receives the local oscillation light through a first circulator, amplifies the local oscillation light through an amplifier, divides the local oscillation light into N paths of local oscillation light through a second optical splitter, and finely adjusts the local oscillation light through finely adjustable delay lines respectively. Each polarization-independent coherent optical receiver receives signal light of the optical link from the second circulator in a one-to-one manner, performs coherent frequency mixing and photoelectric conversion on the signal light and one path of finely adjusted local oscillation light to obtain a group of four-path electric signals, and outputs the four-path electric signals to the N-channel coherent optical modulation and demodulation DSP chip for demodulation. According to the invention, low-cost, low-power-consumption and high-capacity short-distance optical interconnection can be realized.

The invention provides a self-aligned super-junction structure and a preparation method thereof. The method comprises the steps that 1) a substrate of a first doping type is provided, and an epitaxial layer of the first doping type is formed on the upper surface of the substrate of the first doping type; 2) first intrinsic epitaxial layers are formed on the upper surface of the epitaxial layer of the first doping type; 3) a number of parallel spaced trenches are formed in the first intrinsic epitaxial layers; 4) a region of the first doping type and a region of a second doping type are respectively formed in first intrinsic epitaxial layers on two opposite sides of each trench; 5) second intrinsic epitaxial layers are formed in the trenches; and 6) ) the structure acquired in the step 5) is subjected to thermal annealing treatment. Compared with the prior art, the preparation method provided by the invention has the advantages of low requirement on the trench line width, wide process specification, good process compatibility, high product parameter stability, low manufacturing cost and the like.

The invention discloses a non-decision-aided low-complexity time domain sub-symbol optical phase noise suppression method in a coherent light orthogonal frequency division multiplexing system. The method comprises following steps: firstly, cutting received time domain signals into blocks, thus obtaining zero filled sub-symbol vectors; secondly, in adoption of the features of specially designed periodical comb type pilot frequencies, obtaining an observing matrix in a mode without multiplication, extracting offline stored vectors based on pilot frequencies; then estimating sub-symbol optical phase noises by a least square method according to the obtained observing matrix and vectors based on pilot frequencies, compensating the optical phase noises; and finally, switching the signals after phase noise compensation to a frequency domain for channel equalization, and judging and outputting the equalized signals. According to the method of the invention, the complexity is low; the practicability is strong; the demand of the system for the line width of a laser light source is effectively reduced; and the tolerance of the system to the optical phase noises is improved.

The invention discloses a high-threshold power semiconductor device and a manufacturing method thereof. The high-threshold power semiconductor device sequentially comprises a drain metal electrode, asubstrate, a buffer layer and a drift region from bottom to top, and also comprises: a composite column body on the drift region, formed by a drift region protrusion, a columnar p region and a columnar n region, and a channel layer, a passivation layer, a dielectric layer, a heavily doped semiconductor layer, a gate metal electrode and a source metal electrode. The composite column body is formedby sequentially depositing a p-type semiconductor layer and an n-type semiconductor layer on the drift region and then etching the p-type semiconductor layer and the n-type semiconductor layer; wherein the channel layer and the passivation layer are formed by deposition in sequence. Therefore, the device is divided into a cellular region and a terminal region. The dielectric layer, the heavily doped semiconductor layer, the gate metal electrode and the source metal electrode only exist in the cellular region, and the passivation layer of the terminal region extends upwards and wraps the outerside of the channel layer. The structure can improve the threshold voltage of the device, improve the blocking characteristic of the device, and reduce the gate capacitance.