The condition under which a product of two cross-spectral densities (CSD) constitutes a valid correlation function is established. The results are obtained for the CSDs of two one-dimensional, scalar Schell-model sources, but can be readily generalized to other situations. It is shown via a number of numerical examples how new source classes of Schell-model type and the beam-like fields they radiate can be designed.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1364/OL.39.006879 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Environmentally and statistically robust matched-field source localization based on information geometry principles.
J Acoust Soc Am
December 2024
Key Laboratory for Polar Acoustics and Application of Ministry of Education (Harbin Engineering University), Ministry of Education, Harbin, 150001, China.
Matched-field processing (MFP) achieves underwater source localization by measuring the correlation between the array and replica signals, with traditional MFP being equivalent to estimating the Euclidean distance between the data cross-spectral density matrix (CSDM) and replica matrices. However, in practical applications, random inhomogeneities in the marine environment and inaccurate estimation of CSDM reduce MFP performance. The traditional minimum variance matched-field processor with environmental perturbation constraints perturbs a priori environment parameters to obtain linear constraints and yields the optimal weight vectors as the replica vectors.
View Article and Find Full Text PDFDetermination of mode strengths in channel waveguide from the complex electric field.
Sci Rep
November 2024
Center for Photonics Sciences, University of Eastern Finland, P.O. Box 111, 80101, Joensuu, Finland.
We show that the mode strengths of a guided field in an arbitrary asymmetric channel waveguide can be uniquely determined from self-referencing interferometric measurements at the exit plane of the waveguide. This requires knowledge of both the amplitude and phase of the complex electric field distribution. Although the amplitude can be obtained from the measured intensity profile easily, the phase retrieval is usually non-trivial.
View Article and Find Full Text PDFWe introduce a new class of Schell-model source whose spatial correlation function carries a finite series of nontrivial phases and is modulated by cosine function. The propagating formula for the cross-spectral density (CSD) function of the beams generated by this new source in free space is derived and used to investigate the characteristics of the light fields for different modulation parameters. The results show that the appearance of the modulating function and the nontrivial phase sequence cause the radiated fields with extraordinary characteristics during propagation, such as self-splitting and self-interfering in an asymmetric manner.
View Article and Find Full Text PDFUsing the extended Huygens-Fresnel principle, a cross-spectral density formula was developed for a Gaussian Schell model vortex (PCGSMV) beam diffracted through a lensacon (lens with an axicon). The intensity and depth of focus (DOF) shaped by the lensacon were calculated. Our numerical results show the relationship between the intensity distribution and depth of focus with the beam waist width as well as the spatial correlation of the coherence length.
View Article and Find Full Text PDFSpectral dynamic causal modeling: A didactic introduction and its relationship with functional connectivity.
Netw Neurosci
April 2024
Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Australia.
We present a didactic introduction to spectral dynamic causal modeling (DCM), a Bayesian state-space modeling approach used to infer effective connectivity from noninvasive neuroimaging data. Spectral DCM is currently the most widely applied DCM variant for resting-state functional MRI analysis. Our aim is to explain its technical foundations to an audience with limited expertise in state-space modeling and spectral data analysis.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!