Sixty-five new vibronic levels of the Na2 4^3∑g^＋ state have been observed in the 33900-35200 cm^-1 energy region above the potential minimum of the ground state by pulsed perturbation facilitated optical-optical do...Sixty-five new vibronic levels of the Na2 4^3∑g^＋ state have been observed in the 33900-35200 cm^-1 energy region above the potential minimum of the ground state by pulsed perturbation facilitated optical-optical double resonance （PFOODR） fluorescence excitation spectroscopy. These new data fill the gap between the low-v levels mainly observed by continuous wave （CW） PFOODR spectroscopy and the high-v levels above the 3s＋3d limit observed by pulsed PFOODR with predissociation detection, Molecular constants are fitted below potential shelf around the 3s＋3d atomic limit with previously published data （mainly observed by CW PFOODR） and these new data. RKR potential curve has been calculated with the new constants. The constants are： Te= 32127.090 cm^-1,ωe=121.4099（0.20720） cm^-1, Be = 0.116287（0.0002300） cm^-1, Re=3.551 A, An error of the RKR potential curve of J. Chem. Phys. 108, 7707 （1998） is corrected.展开更多
A microwave photonic filter(MPF) based on multi-wavelength fiber laser and infinite impulse response(IIR) is proposed. The filter uses a multi-wavelength fiber laser as the light source, two sections of polarization m...A microwave photonic filter(MPF) based on multi-wavelength fiber laser and infinite impulse response(IIR) is proposed. The filter uses a multi-wavelength fiber laser as the light source, two sections of polarization maintaining fiber(PMF) and three polarization controllers(PCs) as the laser frequency selection device. By adjusting the PC to change the effective length of the PMF, the laser can obtain three wavelength spacings, which are 0.44 nm, 0.78 nm and 1.08 nm, respectively. And the corresponding free spectral ranges(FSRs) are 8.46 GHz, 4.66 GHz and 3.44 GHz, respectively. Thus changing the wavelength spacing of the laser can make the FSR variable. An IIR filter is introduced based on a finite impulse response(FIR) filter. Then the 3-d B bandwidth of the MPF is reduced, and the main side-lobe suppression ratio(MSSR) is increased. By adjusting the gain of the radio frequency(RF) signal amplifier, the frequency response of the filter can be enhanced.展开更多
Based on the transfer matrix method,a detailed theoretical and numerical study on double-phase-shifted fiber Bragg grating(FBG)is investigated.Temporal responses of the double-phase-shifted FBG to optical pulse are an...Based on the transfer matrix method,a detailed theoretical and numerical study on double-phase-shifted fiber Bragg grating(FBG)is investigated.Temporal responses of the double-phase-shifted FBG to optical pulse are analyzed and the influence of the two phase-shifts’position on the reflected output pulse is evaluated.Results demonstrate that very different temporal pulse waveforms can be achieved by adjusting the length ratio(α=L2/L1).Specifically,a transform-limited Gaussian input optical pulse can be shaped into flat-top square pulse(α=1.81)or two identical optical pulse sequences(α=1.93).展开更多
基金This work was supported by the National Natural Science Foundation of China（NSFC No. 20473042, N0. 20173029 and 10174042）, NKBRSF, and SRFDP of China and by RFBR（grant 05-03-39012） of Russia.
文摘Sixty-five new vibronic levels of the Na2 4^3∑g^＋ state have been observed in the 33900-35200 cm^-1 energy region above the potential minimum of the ground state by pulsed perturbation facilitated optical-optical double resonance （PFOODR） fluorescence excitation spectroscopy. These new data fill the gap between the low-v levels mainly observed by continuous wave （CW） PFOODR spectroscopy and the high-v levels above the 3s＋3d limit observed by pulsed PFOODR with predissociation detection, Molecular constants are fitted below potential shelf around the 3s＋3d atomic limit with previously published data （mainly observed by CW PFOODR） and these new data. RKR potential curve has been calculated with the new constants. The constants are： Te= 32127.090 cm^-1,ωe=121.4099（0.20720） cm^-1, Be = 0.116287（0.0002300） cm^-1, Re=3.551 A, An error of the RKR potential curve of J. Chem. Phys. 108, 7707 （1998） is corrected.
基金supported by the National High Technology Research and Development Program of China(No.2013AA014200)the National Natural Science Foundation of China(No.11444001)the Tianjin Natural Science Foundation(No.14JCYBJC16500)
文摘A microwave photonic filter(MPF) based on multi-wavelength fiber laser and infinite impulse response(IIR) is proposed. The filter uses a multi-wavelength fiber laser as the light source, two sections of polarization maintaining fiber(PMF) and three polarization controllers(PCs) as the laser frequency selection device. By adjusting the PC to change the effective length of the PMF, the laser can obtain three wavelength spacings, which are 0.44 nm, 0.78 nm and 1.08 nm, respectively. And the corresponding free spectral ranges(FSRs) are 8.46 GHz, 4.66 GHz and 3.44 GHz, respectively. Thus changing the wavelength spacing of the laser can make the FSR variable. An IIR filter is introduced based on a finite impulse response(FIR) filter. Then the 3-d B bandwidth of the MPF is reduced, and the main side-lobe suppression ratio(MSSR) is increased. By adjusting the gain of the radio frequency(RF) signal amplifier, the frequency response of the filter can be enhanced.
基金supported by the Foundation of Beijing Municipal Committee of CPC Organization Department(No.2012D005002000001)the Talents of North China University of Technology(No.CCXZ201307)the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions(No.CIT&TCD201304001)
文摘Based on the transfer matrix method,a detailed theoretical and numerical study on double-phase-shifted fiber Bragg grating(FBG)is investigated.Temporal responses of the double-phase-shifted FBG to optical pulse are analyzed and the influence of the two phase-shifts’position on the reflected output pulse is evaluated.Results demonstrate that very different temporal pulse waveforms can be achieved by adjusting the length ratio(α=L2/L1).Specifically,a transform-limited Gaussian input optical pulse can be shaped into flat-top square pulse(α=1.81)or two identical optical pulse sequences(α=1.93).
