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We demonstrate a tunable, narrow-band filter based on optical-pumping-induced circular dichroism in rubidium vapor. The filter achieves a peak transmission of 14.6%, a linewidth of 80 MHz, and an out-of-band extinction >35 dB. The…

Integrated optical filter based on microring resonators plays a critical role in many applications, ranging from wavelength division multiplexing and switching to channel routing. Bandwidth tunable filters are capable of meeting the…

Optics · Physics 2022-04-26 Xinda Lu , Nuo Chen , Boqing Zhang , Haofan Yang , Yuntian Chen , Xinliang Zhang , Jing Xu

We seek to cover a parametric domain with a set of evenly spaced bands which number and widthvaries according to a density field. We propose an implicit procedural algorithm, that generates theband pattern from a pixel shader and adapts to…

Computational Geometry · Computer Science 2020-03-04 Jimmy Etienne , Sylvain Lefebvre

Recently, disordered photonic media and random textured surfaces have attracted increasing attention as strong light diffusers with broadband and wide-angle properties. We report the first experimental realization of an isotropic complete…

When designing multispectral imaging systems for classifying different spectra it is necessary to choose a small number of filters from a set with several hundred different ones. Tackling this problem by full search leads to a tremendous…

Image and Video Processing · Electrical Eng. & Systems 2023-01-19 Frank Sippel , Jürgen Seiler , André Kaup

In hyperspectral images, some spectral bands suffer from low signal-to-noise ratio due to noisy acquisition and atmospheric effects, thus requiring robust techniques for the unmixing problem. This paper presents a robust supervised spectral…

Machine Learning · Statistics 2017-10-11 Fei Zhu , Abderrahim Halimi , Paul Honeine , Badong Chen , Nanning Zheng

The high dimensionality of hyperspectral images consisting of several bands often imposes a big computational challenge for image processing. Therefore, spectral band selection is an essential step for removing the irrelevant, noisy and…

Computer Vision and Pattern Recognition · Computer Science 2022-10-27 A. Elmaizi , E. Sarhrouni , A. Hammouch , C. Nacir

Optimal sampling of non band-limited functions is an issue of great importance that has attracted considerable attention. We propose to tackle this problem through the use of a frequency warping: First, by a nonlinear shrinking of…

Classical Analysis and ODEs · Mathematics 2017-03-07 Stefan Lafon , Jacques Lévy Véhel , Jacques Peyrière

Although a lateral-shear interferometer is robust against optical component vibrations, its interferogram provides information about differential wavefronts rather than the wavefronts themselves, resulting in the loss of specific frequency…

Dual-comb interferometry harnesses the interference of two laser frequency combs to provide unprecedented capability in spectroscopy applications. In the past decade, the state-of-the-art systems have reached a point where the…

Quantum Physics · Physics 2023-09-20 Haowei Shi , Zaijun Chen , Scott E. Fraser , Mengjie Yu , Zheshen Zhang , Quntao Zhuang

Automatic discovery and curve fitting of absorption bands in hyperspectral data can enable the analyst to identify materials present in a scene by comparison with library spectra. This procedure is common in laboratory spectra, but is…

Instrumentation and Methods for Astrophysics · Physics 2014-01-23 Adrian J. Brown

In ultrasound imaging the appearance of homogeneous regions of tissue is subject to speckle, which for certain applications can make the detection of tissue irregularities difficult. To cope with this, it is common practice to apply speckle…

Image and Video Processing · Electrical Eng. & Systems 2022-08-02 Rüdiger Göbl , Christoph Hennersperger , Nassir Navab

Broadband beamforming is a technique to obtain the signal with a wide range of frequencies. It maintains the signal integrity and spatial selectivity over frequencies. This is important in several applications such as microphone array,…

Signal Processing · Electrical Eng. & Systems 2020-03-03 Phan Le Son

Banding artifact, as known as staircase-like contour, is a common quality annoyance that happens in compression, transmission, etc. scenarios, which largely affects the user's quality of experience (QoE). The banding distortion typically…

Computer Vision and Pattern Recognition · Computer Science 2023-12-01 Zijian Chen , Wei Sun , Zicheng Zhang , Ru Huang , Fangfang Lu , Xiongkuo Min , Guangtao Zhai , Wenjun Zhang

We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of…

Classical Physics · Physics 2016-09-09 Niels Aage , Villads Egede Johansen

Dual-comb spectroscopy utilizes two sets of comb lines with slightly different comb-tooth-spacings, and optical spectral information is acquired by measuring the radio-frequency beat notes between the sets of comb lines. It holds the…

Optics · Physics 2016-09-13 Xin Zhao , Guoqing Hu , Bofeng Zhao , Cui Li , Yingling Pan , Ya Liu , Takeshi Yasui , Zheng Zheng

In recent years, a great deal of emphasis has been placed on achieving the diffraction limit with large aperture telescopes. For a well matched focal-plane instrument, the diffraction limit provides the highest possible angular resolution…

Astrophysics · Physics 2009-11-11 J. Bland-Hawthorn , A. Horton

We introduce an approach for performing spectrally resolved electron microscopy without the need for an electron spectrometer. The method involves an electron beam prepared as a coherent superposition of multiple paths, one of which passes…

Materials Science · Physics 2025-04-24 F. Javier García de Abajo , Cruz I. Velasco

Microwave transversal filters, which are implemented based on the transversal filter structure in digital signal processing, offer a high reconfigurability for achieving a variety of signal processing functions without changing hardware.…

Optics · Physics 2024-08-08 David J. Moss

The need to Fourier transform data sets with irregular sampling is shared by various domains of science. This is the case for example in astronomy or sismology. Iterative methods have been developed that allow to reach approximate…

Numerical Analysis · Mathematics 2024-01-23 Guy Perrin