High-resolution approaches such as multiple signal classification and estimation of signal parameters via rotational invariance techniques(ESPRIT) are currently employed widely in multibeam echo-sounder(MBES)syste...High-resolution approaches such as multiple signal classification and estimation of signal parameters via rotational invariance techniques(ESPRIT) are currently employed widely in multibeam echo-sounder(MBES)systems for sea floor bathymetry,where a uniform line array is also required.However,due to the requirements in terms of the system coverage/resolution and installation space constraints,an MBES system usually employs a receiving array with a special shape,which means that high-resolution algorithms cannot be applied directly.In addition,the short-term stationary echo signals make it difficult to estimate the covariance matrix required by the high-resolution approaches,which further increases the complexity when applying the high-resolution algorithms in the MBES systems.The ESPRIT with multiple-angle subarray beamforming is employed to reduce the requirements in terms of the signal-to-noise ratio,number of snapshots,and computational effort.The simulations show that the new processing method can provide better fine-structure resolution.Then a highresolution bottom detection(HRBD) algorithm is developed by combining the new processing method with virtual array transformation.The application of the HRBD algorithm to a U-shaped array is also discuss.The computer simulations and experimental data processing results verify the effectiveness of the proposed algorithm.展开更多
The concept of difference and sum(diff-sum)coarray has attracted a lot of attentions in the estimation of direction-of-arrival(DOA)for the past few years,due to its high degrees-of-freedom(DOFs).A vectorized conjugate...The concept of difference and sum(diff-sum)coarray has attracted a lot of attentions in the estimation of direction-of-arrival(DOA)for the past few years,due to its high degrees-of-freedom(DOFs).A vectorized conjugate augmented MUSIC(VCA-MUSIC)algorithm is applied to generate an equivalent signal model which contains the virtual sensor positions of both the difference and sum of the physical sensors in the two-dimensional(2D)arrays,by utilizing both the spatial and temporal information.Besides,an augmented 2D coprime array configuration is presented with the basis on the concept of difference and sum coarray.By compressing the inter-element spacing of one subarray and introducing the proper separation between the two subarrays of 2D coprime array,the redundancy between the difference coarray and the sum one can be reduced so that more virtual sensors in both coarrays can make contributions to the DOFs.As a result,a much larger consecutive area in the diff-sum coarray can be achieved,which can significantly increase the DOFs.Numerical simulations verify the superiority of the proposed array configuration.展开更多
High-repetition-rate(HRR) pulsed fiber lasers have attracted much attention in various fields. To effectively achieve HRR pulses in fiber lasers, dissipative four-wave-mixing mode-locking is a promising method. In thi...High-repetition-rate(HRR) pulsed fiber lasers have attracted much attention in various fields. To effectively achieve HRR pulses in fiber lasers, dissipative four-wave-mixing mode-locking is a promising method. In this work, we demonstrated an HRR pulsed fiber laser based on a virtually imaged phased array(VIPA), serving as a comb filter. Due to the high spectral resolution and low polarization sensitivity features of VIPA, the 30 GHz pulse with high quality and high stability could be obtained. In the experiments, both the single-waveband and dual-waveband HRR pulses were achieved. Such an HRR pulsed fiber laser could have potential applications in related fields, such as optical communications.展开更多
We demonstrate a two-component detection of a coherent population trapping(CPT)resonance based on virtually imaged phased array(VIPA).After passing through a VIPA,the two coupling lights with different frequencies in ...We demonstrate a two-component detection of a coherent population trapping(CPT)resonance based on virtually imaged phased array(VIPA).After passing through a VIPA,the two coupling lights with different frequencies in the CPT experiment are separated in space and detected individually.The asymmetric lineshape is observed experimentally in the CPT signal for each component,and the comparison with the conventional detection is presented.The shift of the CPT resonant frequency is studied with both the two-component and one-component detections.Our scheme provides a convenient way to further study the CPT phenomenon for each frequency component.展开更多
基金The National Natural Science Foundation of China under contract No.41706066the National Key R&D Program of China under contract No.2016YFC1400200the China-ASEAN Maritime Cooperation Fund
文摘High-resolution approaches such as multiple signal classification and estimation of signal parameters via rotational invariance techniques(ESPRIT) are currently employed widely in multibeam echo-sounder(MBES)systems for sea floor bathymetry,where a uniform line array is also required.However,due to the requirements in terms of the system coverage/resolution and installation space constraints,an MBES system usually employs a receiving array with a special shape,which means that high-resolution algorithms cannot be applied directly.In addition,the short-term stationary echo signals make it difficult to estimate the covariance matrix required by the high-resolution approaches,which further increases the complexity when applying the high-resolution algorithms in the MBES systems.The ESPRIT with multiple-angle subarray beamforming is employed to reduce the requirements in terms of the signal-to-noise ratio,number of snapshots,and computational effort.The simulations show that the new processing method can provide better fine-structure resolution.Then a highresolution bottom detection(HRBD) algorithm is developed by combining the new processing method with virtual array transformation.The application of the HRBD algorithm to a U-shaped array is also discuss.The computer simulations and experimental data processing results verify the effectiveness of the proposed algorithm.
基金Supported by the National Natural Science Foundation of China(61801024)。
文摘The concept of difference and sum(diff-sum)coarray has attracted a lot of attentions in the estimation of direction-of-arrival(DOA)for the past few years,due to its high degrees-of-freedom(DOFs).A vectorized conjugate augmented MUSIC(VCA-MUSIC)algorithm is applied to generate an equivalent signal model which contains the virtual sensor positions of both the difference and sum of the physical sensors in the two-dimensional(2D)arrays,by utilizing both the spatial and temporal information.Besides,an augmented 2D coprime array configuration is presented with the basis on the concept of difference and sum coarray.By compressing the inter-element spacing of one subarray and introducing the proper separation between the two subarrays of 2D coprime array,the redundancy between the difference coarray and the sum one can be reduced so that more virtual sensors in both coarrays can make contributions to the DOFs.As a result,a much larger consecutive area in the diff-sum coarray can be achieved,which can significantly increase the DOFs.Numerical simulations verify the superiority of the proposed array configuration.
基金supported in part by the National Natural Science Foundation of China(NSFC)(Nos.61805084,11974006,11874018 and 61875058)Science and Technology Program of Guangzhou(No.2019050001)+4 种基金Guangdong Key R&D Program(No.2018B090904003)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515010879)Foundation for Young Talents in Higher Education of Guangdong(No.2017KQNCX051)Scientific Research Foundation of Young Teacher of South China Normal University(No.17KJ09)Open Fund of the Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques(South China University of Technology,2019-2)
文摘High-repetition-rate(HRR) pulsed fiber lasers have attracted much attention in various fields. To effectively achieve HRR pulses in fiber lasers, dissipative four-wave-mixing mode-locking is a promising method. In this work, we demonstrated an HRR pulsed fiber laser based on a virtually imaged phased array(VIPA), serving as a comb filter. Due to the high spectral resolution and low polarization sensitivity features of VIPA, the 30 GHz pulse with high quality and high stability could be obtained. In the experiments, both the single-waveband and dual-waveband HRR pulses were achieved. Such an HRR pulsed fiber laser could have potential applications in related fields, such as optical communications.
基金supported by the National Natural Science Foundation of China(Nos.12005187 and 91536220)。
文摘We demonstrate a two-component detection of a coherent population trapping(CPT)resonance based on virtually imaged phased array(VIPA).After passing through a VIPA,the two coupling lights with different frequencies in the CPT experiment are separated in space and detected individually.The asymmetric lineshape is observed experimentally in the CPT signal for each component,and the comparison with the conventional detection is presented.The shift of the CPT resonant frequency is studied with both the two-component and one-component detections.Our scheme provides a convenient way to further study the CPT phenomenon for each frequency component.