A single-frequency retrievable phase modulated multi-tone fiber amplifier is presented in theory and demonstrated in experiment. A multi-tone seed laser generated by a sine wave phase modulated single-frequency laser ...A single-frequency retrievable phase modulated multi-tone fiber amplifier is presented in theory and demonstrated in experiment. A multi-tone seed laser generated by a sine wave phase modulated single-frequency laser is employed for stimulated Brillouin scattering suppression in an all-fiber amplifier. A demodulation signal which is π phase shifted with respect to the modulation signal is used to retrieve the single-frequency laser from the multi-tone laser. In experiment, we first optimize the all-fiber master-oscillator power-amplifier. With this amplifier, we demonstrate a single-frequency retrievable multi-tone laser with 330-W output when driven by the multi-tone seed, while the ultimate output power is only 130 W when driven by the single-frequency laser. Then, we carry out an experiment for retrieving the single-frequency laser from the amplified multi-tone laser. Results indicate that the single-frequency laser can be retrieved with a sideband suppression of more than 20 dB. Retrieving an even higher power single-frequency laser is possible if a high power demodulator is available.展开更多
In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) a...In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) are studied in this paper. The time-domain synchronization,frequency synchronization and channel equalization of receiver are analyzed and optimized by utilizing short and long training preamble. Moreover,field programmable gate array(FPGA) development board(Xilinx Kintex-7) and Verilog hardware description language are used to realize the design of proposed OFDM-VLC system. Simulation and experiment both verify the feasibility of the hardware designs of this system. The proposed OFDM-based VLC system can process signal in real-time,which can be used in actual VLC application systems.展开更多
Facing the body's EEG(electroencephalograph, 0.5–100 Hz, 5–100 μV) and ECG's(electrocardiogram,〈 100 Hz, 0.01–5 mV) micro signal detection requirement, this paper develops a pervasive application micro sign...Facing the body's EEG(electroencephalograph, 0.5–100 Hz, 5–100 μV) and ECG's(electrocardiogram,〈 100 Hz, 0.01–5 mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL(ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier's outputting terminal. The single-stage chopping core's noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB(positive feedback loop) to increase the inputting resistance, and the NFB(negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF(voltage gain amplifier/band pass filter) circuit is used to tune the chopper system's gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters: 8.1 μW/channel, 0.8 μVrms(@band-widthD100 Hz), 4216–11220 times digitally tuning gain range, etc. The data capture system uses the NI CO's data capturing DAQmx interface,and the captured micro EEG/ECG's waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal's detection instrument and has a critical real application value.展开更多
A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noi...A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noise low-offset charge integrator is employed in this circuit to implement a capacitance-to-voltage converter and minimize the noise and offset. The application-specific integrated circuit (ASIC) is fabricated in a 0.5 /μm one-ploy three-metal CMOS process. The measured results of the proposed circuit show that the noise floor of the ASIC is -116 dBV, the sensitivity of the accelerometer is 66 mV/g with a nonlinearity of 0.5%. The chip occupies 3.5×2.5 mm2 and the current is 3.5 mA.展开更多
基金Project supported by the New Century Excellent Talents in University, Ministry of Education of China and the Scientific Research Project in National University Defense of Technology
文摘A single-frequency retrievable phase modulated multi-tone fiber amplifier is presented in theory and demonstrated in experiment. A multi-tone seed laser generated by a sine wave phase modulated single-frequency laser is employed for stimulated Brillouin scattering suppression in an all-fiber amplifier. A demodulation signal which is π phase shifted with respect to the modulation signal is used to retrieve the single-frequency laser from the multi-tone laser. In experiment, we first optimize the all-fiber master-oscillator power-amplifier. With this amplifier, we demonstrate a single-frequency retrievable multi-tone laser with 330-W output when driven by the multi-tone seed, while the ultimate output power is only 130 W when driven by the single-frequency laser. Then, we carry out an experiment for retrieving the single-frequency laser from the amplified multi-tone laser. Results indicate that the single-frequency laser can be retrieved with a sideband suppression of more than 20 dB. Retrieving an even higher power single-frequency laser is possible if a high power demodulator is available.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2015AA033303)the National Key Basic Research Program of China(973 program)(No.2013CB329204)+1 种基金the National Nature Science Foundation of China(Nos.61178051,61321063 and 61335010)the Science and Technology Project of Guangdong Province in China(No.2014B010120004)
文摘In order to ensure stable,correct and real-time high-speed transmission of indoor visible light communication(VLC),the key modulation and demodulation technologies of orthogonal frequency division multiplexing(OFDM) are studied in this paper. The time-domain synchronization,frequency synchronization and channel equalization of receiver are analyzed and optimized by utilizing short and long training preamble. Moreover,field programmable gate array(FPGA) development board(Xilinx Kintex-7) and Verilog hardware description language are used to realize the design of proposed OFDM-VLC system. Simulation and experiment both verify the feasibility of the hardware designs of this system. The proposed OFDM-based VLC system can process signal in real-time,which can be used in actual VLC application systems.
基金Project supported by the National Natural Science Foundation of China(Nos.61527815,31500800,61501426,61471342)the National Key Basic Research Plan(No.2014CB744600)+1 种基金the Beijing Science and Technology Plan(No.Z141100000214002)the Chinese Academy of Sciences’Key Project(No.KJZD-EW-L11-2)
文摘Facing the body's EEG(electroencephalograph, 0.5–100 Hz, 5–100 μV) and ECG's(electrocardiogram,〈 100 Hz, 0.01–5 mV) micro signal detection requirement, this paper develops a pervasive application micro signal detection ASIC chip with the chopping modulation/demodulation method. The chopper-stabilization circuit with the RRL(ripple reduction loop) circuit is to suppress the ripple voltage, which locates at the single-stage amplifier's outputting terminal. The single-stage chopping core's noise has been suppressed too, and it is beneficial for suppressing noises of post-circuit. The chopping core circuit uses the PFB(positive feedback loop) to increase the inputting resistance, and the NFB(negative feedback loop) to stabilize the 40 dB intermediate frequency gain. The cascaded switch-capacitor sample/hold circuit has been used for deleting spike noises caused by non-ideal MOS switches, and the VGA/BPF(voltage gain amplifier/band pass filter) circuit is used to tune the chopper system's gain/bandwidth digitally. Assisted with the designed novel dry-electrode, the real test result of the chopping amplifying circuit gives some critical parameters: 8.1 μW/channel, 0.8 μVrms(@band-widthD100 Hz), 4216–11220 times digitally tuning gain range, etc. The data capture system uses the NI CO's data capturing DAQmx interface,and the captured micro EEG/ECG's waves are real-time displayed with the PC-Labview. The proposed chopper system is a unified EEG/ECG signal's detection instrument and has a critical real application value.
文摘A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noise low-offset charge integrator is employed in this circuit to implement a capacitance-to-voltage converter and minimize the noise and offset. The application-specific integrated circuit (ASIC) is fabricated in a 0.5 /μm one-ploy three-metal CMOS process. The measured results of the proposed circuit show that the noise floor of the ASIC is -116 dBV, the sensitivity of the accelerometer is 66 mV/g with a nonlinearity of 0.5%. The chip occupies 3.5×2.5 mm2 and the current is 3.5 mA.