The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium （Yb）-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially des...The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium （Yb）-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification （CPA） system and generates mode-locked pulses with hundreds of picosecond widths. Two kinds of large-mode-area （LMA） double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier. All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio （SNR）. The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission （ASE） is suppressed to better than 30 dB, and the onset of stimulated Raman scattering is excluded.展开更多
A scheme of multi-wavelength pulse generator using optical frequency comb and arrayed waveguide grating （AWG） is proposed and experimentally demonstrated. A flattop optical frequency comb is shaped into multiple nar...A scheme of multi-wavelength pulse generator using optical frequency comb and arrayed waveguide grating （AWG） is proposed and experimentally demonstrated. A flattop optical frequency comb is shaped into multiple narrowband Gaussian spectra by using an AWG which contains a number of Gaussian channels, and then multi-wavelength optical pulses are achieved. In the experiment, six wavelength pulses with full width at half-maximum （FWHM） of 14.6 ps at I0 GHz are obtained, and two wavelength-interleaved pulse trains at 20 GHz and four wavelength-interleaved multi-wavelength optical pulses. This scheme has and time-interval can be readily controlled. pulse trains at 40 GHz are demonstrated by using the flexibility because the pulse width, the repetition rate,展开更多
This paper focuses on the simulation and test of the switched reluctance starter/generator systems. Through the emulational analysis of the initial starting torque, the optimal turn-on section of the power switches is...This paper focuses on the simulation and test of the switched reluctance starter/generator systems. Through the emulational analysis of the initial starting torque, the optimal turn-on section of the power switches is discovered. The fundamental theory of the generating operation is analyzed with the linearity model, and a new method is presented based on voltage pulse width modulation for the generating mode control. Through the steady-state and optimized emulation of the output power and system efficiency, the optimizational control approach for the generating mode over a wide speed range is introduced. At last, the test of the 3KW prototype system shows that the dynamic and static performance of this system is fine.展开更多
An 8×10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroab-sorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which gen...An 8×10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroab-sorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which generated stable 10-GHz, 2-ps full-width at half-maximum (FWHM) pulse train, an optoelectronic oscillator (OEO) that extracted 10-GHz clock with a timing jitter of 300 fs from 80-Gb/s OTDM signal and a self cascaded EAM which produced a switching window of about 10 ps. A back-to-back error free demultiplexing experiment with a power penalty of 3.25 dB was carried out to verify the system performance.展开更多
We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intens...We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.展开更多
Hundreds picosecond strong short-wavelength pulses have been generate by a backward Raman oscillator amplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also high energy laser pul...Hundreds picosecond strong short-wavelength pulses have been generate by a backward Raman oscillator amplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also high energy laser pulses have been obtained with an energy conversion efficiency up to 17%. 640-picosecond pulse duration was observed in our experiments by a 1.5-GHz-bandwidth oscilloscope corresponding to 34 times of pulse compression rate.展开更多
A compact Er：fiber ring laser operated at a fundamental repetition rate of 325 MHz is reported. Two gain fibers with opposite dispersion are employed to shorten the fiber laser cavity for high repetition rate and sol...A compact Er：fiber ring laser operated at a fundamental repetition rate of 325 MHz is reported. Two gain fibers with opposite dispersion are employed to shorten the fiber laser cavity for high repetition rate and soliton-like pulse generation without losing gain and compactness. The spectral bandwidth of the output pulse is 24 nm and the direct pulse duration is 123 fs without extra-cavity compression, which are values near the transform-Hmited range.展开更多
基金supported by the National Key Natural Science Foundation of China under Grant No. 60537060
文摘The efficient generation of a 1.17-mJ laser pulse with 360 ps duration using an ytterbium （Yb）-doped fiber amplifier chain seeded by a homemade mode-locked fiber laser is demonstrated experimentally. A specially designed figure-of-eight fiber laser acts as the seed source of a chirped-pulse amplification （CPA） system and generates mode-locked pulses with hundreds of picosecond widths. Two kinds of large-mode-area （LMA） double-clad Yb-doped fibers are employed to construct the pre-amplifier and main amplifier. All of the adopted instruments help avoid severe nonlinearity in fibers to raise sub-nanosecond pulse energy with acceptable signal-to-noise ratio （SNR）. The output spectrum of this fiber-based CPA system shows that amplified spontaneous emission （ASE） is suppressed to better than 30 dB, and the onset of stimulated Raman scattering is excluded.
基金supported by the National Natural Science Foundation of China under Grant Nos. 60977003and 61032005
文摘A scheme of multi-wavelength pulse generator using optical frequency comb and arrayed waveguide grating （AWG） is proposed and experimentally demonstrated. A flattop optical frequency comb is shaped into multiple narrowband Gaussian spectra by using an AWG which contains a number of Gaussian channels, and then multi-wavelength optical pulses are achieved. In the experiment, six wavelength pulses with full width at half-maximum （FWHM） of 14.6 ps at I0 GHz are obtained, and two wavelength-interleaved pulse trains at 20 GHz and four wavelength-interleaved multi-wavelength optical pulses. This scheme has and time-interval can be readily controlled. pulse trains at 40 GHz are demonstrated by using the flexibility because the pulse width, the repetition rate,
文摘This paper focuses on the simulation and test of the switched reluctance starter/generator systems. Through the emulational analysis of the initial starting torque, the optimal turn-on section of the power switches is discovered. The fundamental theory of the generating operation is analyzed with the linearity model, and a new method is presented based on voltage pulse width modulation for the generating mode control. Through the steady-state and optimized emulation of the output power and system efficiency, the optimizational control approach for the generating mode over a wide speed range is introduced. At last, the test of the 3KW prototype system shows that the dynamic and static performance of this system is fine.
基金This work was supported by the National Natural Science Foundation of China under Grant No. 60444008904010247 and 60177019.
文摘An 8×10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroab-sorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which generated stable 10-GHz, 2-ps full-width at half-maximum (FWHM) pulse train, an optoelectronic oscillator (OEO) that extracted 10-GHz clock with a timing jitter of 300 fs from 80-Gb/s OTDM signal and a self cascaded EAM which produced a switching window of about 10 ps. A back-to-back error free demultiplexing experiment with a power penalty of 3.25 dB was carried out to verify the system performance.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274115 and 10990101)the National Key Project for Basic Research of China(Grant No.2011CB808105)+2 种基金the National Key Scientific Instrument Project,China(Grant No.2012YQ150092)the Natural Science Foundation of Shanghai,China(Grant No.11ZR1410900)the Innovation Program of Shanghai Municipal Education Commission,China(Grant No.2014Z10269011)
文摘We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.
基金This work was supported by the National High Technology Research and Development Program of China (863 Program, 863-804-6, No. 2002AA846020)the China Institute of Atomic Energy.
文摘Hundreds picosecond strong short-wavelength pulses have been generate by a backward Raman oscillator amplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also high energy laser pulses have been obtained with an energy conversion efficiency up to 17%. 640-picosecond pulse duration was observed in our experiments by a 1.5-GHz-bandwidth oscilloscope corresponding to 34 times of pulse compression rate.
基金supported by the National "973" Program of China (No. 2013CB922400)the National Natural Science Foundation of China (Nos. 60927010,10974006,and 11027404)the Templeton Foundation
文摘A compact Er：fiber ring laser operated at a fundamental repetition rate of 325 MHz is reported. Two gain fibers with opposite dispersion are employed to shorten the fiber laser cavity for high repetition rate and soliton-like pulse generation without losing gain and compactness. The spectral bandwidth of the output pulse is 24 nm and the direct pulse duration is 123 fs without extra-cavity compression, which are values near the transform-Hmited range.
