In the contrast source inversion(CSI)method,the contrast sources(equiva-lent scattering sources)and the contrast(parameter perturbation)are iteratively recon-structed by an alternating optimization scheme.Traditionall...In the contrast source inversion(CSI)method,the contrast sources(equiva-lent scattering sources)and the contrast(parameter perturbation)are iteratively recon-structed by an alternating optimization scheme.Traditionally integral equation CSI method is formulated for transmission tomography using analytic Green’s function in homogeneous background.To extend the method to the case of reflection seismology,in this paper,we use WKBJ method to compute the Green’s function of depth dependent background media and the solving method of equations to initialize the contrast source of different frequencies,resulting in an efficient method to invert multi-frequency reflection seismic data–multi-frequency contrast source inversion method(MFCSI).Numerical results for the Marmousi model show that MFCSI method can obtain good results even when low frequency data are missing,in which case the conventional FWI fails.展开更多
Periodically poled lithium niobate on insulator(LNOI) ridge waveguides are desirable for high-efficiency nonlinear frequency conversions, and the fabrication process of such waveguides is crucial for device performanc...Periodically poled lithium niobate on insulator(LNOI) ridge waveguides are desirable for high-efficiency nonlinear frequency conversions, and the fabrication process of such waveguides is crucial for device performance. In this work, we report fabrication and characterization of locally periodically poled ridge waveguides. Ridge waveguides were fabricated by dry etching, and then the high-voltage pulses were applied to locally poled ridge waveguides. Second harmonic generation with normalized conversion efficiency of 435.5% W^(-1)·cm^(-2) was obtained in the periodically poled LNOI ridge waveguide,which was consistent with the triangular domain structure revealed by confocal microscopy.展开更多
基金supported by the National Science and Technology of Major Projects of China(grant no.2016ZX05024-001-004)the WTOPI Research Consortium of Modeling and Imaging Laboratory,University of California Santa Cruz,US。
文摘In the contrast source inversion(CSI)method,the contrast sources(equiva-lent scattering sources)and the contrast(parameter perturbation)are iteratively recon-structed by an alternating optimization scheme.Traditionally integral equation CSI method is formulated for transmission tomography using analytic Green’s function in homogeneous background.To extend the method to the case of reflection seismology,in this paper,we use WKBJ method to compute the Green’s function of depth dependent background media and the solving method of equations to initialize the contrast source of different frequencies,resulting in an efficient method to invert multi-frequency reflection seismic data–multi-frequency contrast source inversion method(MFCSI).Numerical results for the Marmousi model show that MFCSI method can obtain good results even when low frequency data are missing,in which case the conventional FWI fails.
基金supported by the National Key R&D Program of China(Nos.2019YFA0705000 and 2017YFA0303700)the National Natural Science Foundation of China(Nos.91950206,11627810,and 51890861)+2 种基金the Leading-edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the Key R&D Program of Guangdong Province(No.2018B030329001)the Fundamental Research Funds for the Central Universities(No.021314380177)。
文摘Periodically poled lithium niobate on insulator(LNOI) ridge waveguides are desirable for high-efficiency nonlinear frequency conversions, and the fabrication process of such waveguides is crucial for device performance. In this work, we report fabrication and characterization of locally periodically poled ridge waveguides. Ridge waveguides were fabricated by dry etching, and then the high-voltage pulses were applied to locally poled ridge waveguides. Second harmonic generation with normalized conversion efficiency of 435.5% W^(-1)·cm^(-2) was obtained in the periodically poled LNOI ridge waveguide,which was consistent with the triangular domain structure revealed by confocal microscopy.
