The Experts below are selected from a list of 179862 Experts worldwide ranked by ideXlab platform
Jianping Yao - One of the best experts on this subject based on the ideXlab platform.
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arbitrary phase modulated rf signal generation based on optical pulse position modulation
Journal of Lightwave Technology, 2008Co-Authors: Yitang Dai, Jianping YaoAbstract:In this paper, the generation of an arbitrary band-limited phase-modulated RF signal from a pulse-position-modulated (PPM) optical pulse train is investigated. We show that a specifically designed PPM pulse train would have a multichannel spectral response, with one channel having the spectrum corresponding to a phase-modulated RF signal. By using a microwave bandpass filter to select the channel of interest, a phase-modulated RF signal is obtained. The relationship between the pulse position modulation and the phase modulation is derived and analyzed. Two design examples are presented, with one for the generation of a chirped RF signal, and the other for the generation of a binary phase-coded RF signal. The chirped pulse has a Central Frequency of 50 GHz and a 3-dB bandwidth of 12.5 GHz. The binary phase-coded RF pulse has 15 chips with a Central Frequency of 5.34 GHz. The proposed approach provides a simple and effective solution for the generation of high-speed arbitrary phase-modulated RF waveforms for applications in modern radar, communications, and imaging systems.
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chirped rf pulse generation based on optical spectral shaping and wavelength to time mapping using a nonlinearly chirped fiber bragg grating
Journal of Lightwave Technology, 2008Co-Authors: Hao Chi, Jianping YaoAbstract:Chirped radio-Frequency (RF) pulse generation based on optical spectral shaping and nonlinear wavelength-to-time mapping in a nonlinearly chirped fiber Bragg grating (NLCFBG) is investigated. In the proposed approach, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is shaped by an optical filter that has a sinusoidal Frequency response. The spectrum-shaped optical pulse is sent to the NLCFBG, to implement nonlinear wavelength-to-time mapping. A chirped electrical pulse with the Central Frequency and chirp rate determined respectively by the first- and second-order dispersions of the NLCFBG is then obtained at the output of a high-speed photodetector. An approximate model that describes the chirped RF pulse generation is derived, which is verified by numerical simulations. Chirped pulse generation with a pulse compression ratio as high as 450 is demonstrated. The key device in the chirped RF pulse generation system is the NLCFBG, which is investigated in detail with an emphasis on the influence of its group delay ripples on the performance of the pulse generation system. Techniques to design and fabricate the NLCFBG are also discussed. The proposed approach provides a potential solution for the generation of chirped RF pulse with a high Central Frequency and large chirp rate for applications in pulse compression radar systems.
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photonic generation of chirped millimeter wave pulses based on nonlinear Frequency to time mapping in a nonlinearly chirped fiber bragg grating
IEEE Transactions on Microwave Theory and Techniques, 2008Co-Authors: Chao Wang, Jianping YaoAbstract:A novel approach to optically generating chirped millimeter-wave pulses with tunable chirp rate based on spectral shaping and nonlinear Frequency-to-time mapping is proposed and experimentally demonstrated. In the proposed approach, the optical power spectrum of an ultrashort pulse from a femtosecond pulsed laser is shaped by a two-tap Sagnac loop filter that has a sinusoidal Frequency response. The spectrum-shaped optical pulse is then sent to a nonlinearly chirped fiber Bragg grating (NL-CFBG) with a tunable nonlinear group delay to serve as a high-order dispersive device to perform the nonlinear Frequency-to-time mapping. A chirped electrical pulse with a high Central Frequency and large chirp rate is then generated at the output of a high-speed photodetector. The NL-CFBG used in the proposed system is produced from a regular linearly chirped fiber Bragg grating based on strain-gradient beam tuning. A detailed theoretical analysis on the chirped pulse generation is developed, which is verified by numerical simulations and experiments. Millimeter-wave pulses with a Central Frequency of around 35 GHz and instantaneous Frequency chirp rates of 0.053 and 0.074 GHz/ps are experimentally generated.
Chao Wang - One of the best experts on this subject based on the ideXlab platform.
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photonic generation of chirped millimeter wave pulses based on nonlinear Frequency to time mapping in a nonlinearly chirped fiber bragg grating
IEEE Transactions on Microwave Theory and Techniques, 2008Co-Authors: Chao Wang, Jianping YaoAbstract:A novel approach to optically generating chirped millimeter-wave pulses with tunable chirp rate based on spectral shaping and nonlinear Frequency-to-time mapping is proposed and experimentally demonstrated. In the proposed approach, the optical power spectrum of an ultrashort pulse from a femtosecond pulsed laser is shaped by a two-tap Sagnac loop filter that has a sinusoidal Frequency response. The spectrum-shaped optical pulse is then sent to a nonlinearly chirped fiber Bragg grating (NL-CFBG) with a tunable nonlinear group delay to serve as a high-order dispersive device to perform the nonlinear Frequency-to-time mapping. A chirped electrical pulse with a high Central Frequency and large chirp rate is then generated at the output of a high-speed photodetector. The NL-CFBG used in the proposed system is produced from a regular linearly chirped fiber Bragg grating based on strain-gradient beam tuning. A detailed theoretical analysis on the chirped pulse generation is developed, which is verified by numerical simulations and experiments. Millimeter-wave pulses with a Central Frequency of around 35 GHz and instantaneous Frequency chirp rates of 0.053 and 0.074 GHz/ps are experimentally generated.
Perry Ping Shum - One of the best experts on this subject based on the ideXlab platform.
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programmable wavelength tunable second order optical temporal differentiator based on a linearly chirped fiber bragg grating and a digital thermal controller
Optics Letters, 2014Co-Authors: Hailiang Zhang, Ming Tang, Yiwei Xie, Deming Liu, Perry Ping ShumAbstract:We proposed and experimentally demonstrated an all-fiber structured wavelength-tunable second-order optical temporal differentiator based on a linearly chirped fiber Bragg grating and a digital-controlled thermal array. The Central Frequency of the differentiation can be reconfigured from 192.141 to 192.616 THz by a programmable circuit. In the experiment, a second-order differentiator with 3 dB bandwidth of 0.086 THz is achieved with a root mean square error of 4.89%.
Hao Chi - One of the best experts on this subject based on the ideXlab platform.
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chirped rf pulse generation based on optical spectral shaping and wavelength to time mapping using a nonlinearly chirped fiber bragg grating
Journal of Lightwave Technology, 2008Co-Authors: Hao Chi, Jianping YaoAbstract:Chirped radio-Frequency (RF) pulse generation based on optical spectral shaping and nonlinear wavelength-to-time mapping in a nonlinearly chirped fiber Bragg grating (NLCFBG) is investigated. In the proposed approach, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is shaped by an optical filter that has a sinusoidal Frequency response. The spectrum-shaped optical pulse is sent to the NLCFBG, to implement nonlinear wavelength-to-time mapping. A chirped electrical pulse with the Central Frequency and chirp rate determined respectively by the first- and second-order dispersions of the NLCFBG is then obtained at the output of a high-speed photodetector. An approximate model that describes the chirped RF pulse generation is derived, which is verified by numerical simulations. Chirped pulse generation with a pulse compression ratio as high as 450 is demonstrated. The key device in the chirped RF pulse generation system is the NLCFBG, which is investigated in detail with an emphasis on the influence of its group delay ripples on the performance of the pulse generation system. Techniques to design and fabricate the NLCFBG are also discussed. The proposed approach provides a potential solution for the generation of chirped RF pulse with a high Central Frequency and large chirp rate for applications in pulse compression radar systems.
Yong Liu - One of the best experts on this subject based on the ideXlab platform.
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photonics assisted bandwidth doubling dual chirp microwave signal generation with freely tunable Central Frequency
IEEE Photonics Journal, 2020Co-Authors: Lingjie Zhang, Zhen Zeng, Yaowen Zhang, Zhiyao Zhang, Bao Sun, Shangjian Zhang, Yali Zhang, Yong LiuAbstract:A photonics-assisted dual-chirp microwave signal generation scheme is proposed based on electro-optic modulation and heterodyne detection. The dual-chirp microwave signal is generated by heterodyne beating between a dual-chirp optical waveform and a Frequency-shifted optical carrier, where the dual-chirp optical waveform is obtained by applying a baseband symmetric-triangle linear Frequency modulated signal to a Mach-Zehnder modulator biased at the minimum transmission point, and the Frequency-shifted optical carrier is obtained by carrier-suppressed single-sideband modulation in a dual-parallel Mach-Zehnder modulator (DPMZM) with the assistance of an electronic 90° hybrid. The bandwidth of the generated dual-chirp microwave signal is twice of that of the input baseband signal, and the Central Frequency can be tuned by varying the Frequency of the single-tone microwave signal applied to the DPMZM. Both numerical simulation and experiment are carried out to demonstrate the proposed scheme. In the simulation, a dual-chirp microwave signal with a center Frequency of 15 GHz and a bandwidth of 6 GHz is generated. In the proof-of-concept experiment, dual-chirp microwave signals centered at 1.5 GHz and with bandwidth of 100 MHz and 200 MHz are generated, which verifies the feasibility of the proposed scheme.