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We present a five level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the…

Quantum Physics · Physics 2011-03-17 Steven A. Sagona-Stophel , James Owen Weatherall , Christopher P. Search

The time series of light reflected from exoplanets by future direct imaging can provide spatial information with respect to the planetary surface. We apply sparse modeling to the retrieval method that disentangles the spatial and spectral…

Earth and Planetary Astrophysics · Physics 2022-05-25 Atsuki Kuwata , Hajime Kawahara , Masataka Aizawa , Takayuki Kotani , Motohide Tamura

Historically, spectroscopic techniques have been essential for studying the optical properties of thin solid films. However, existing formulae for both normal transmission and reflection spectroscopy often rely on simplified theoretical…

We develop a new method for analytical inversion of binned exoplanet transit spectra and for retrieval of planet parameters. The method has a geometrical interpretation and treats each observed spectrum as a single vector $\vec r$ in the…

Earth and Planetary Astrophysics · Physics 2022-11-16 Konstantin T. Matchev , Katia Matcheva , Alexander Roman

Reflectance bounds the frequency spectrum of illumination in the object appearance. In this paper, we introduce the first stochastic inverse rendering method, which recovers the attenuated frequency spectrum of an illumination jointly with…

Computer Vision and Pattern Recognition · Computer Science 2024-03-27 Yuto Enyo , Ko Nishino

We re-examine scattering of photons near the Lyman-alpha resonance in the intergalactic medium (IGM). We first derive a general integral solution for the radiation field around resonance when spin diffusivity is ignored. Our solution shows…

Astrophysics · Physics 2009-11-11 Steven Furlanetto , Jonathan R. Pritchard

Optical spectrometers have propelled scientific and technological advancements in a wide range of fields. While sophisticated systems with excellent performance metrics are serving well in controlled laboratory environments, many…

Optics · Physics 2021-08-05 Naresh Sharma , Govind Kumar , Vivek Garg , Rakesh G. Mote , Shilpi Gupta

In this paper we present XNICER, an optimized multi-band extinction technique based on the extreme deconvolution of the intrinsic colors of objects observed through a molecular cloud. XNICER follows a rigorous statistical approach and…

Instrumentation and Methods for Astrophysics · Physics 2019-05-03 Marco Lombardi

Light passing through scattering media will be strongly scattered and diffused into complex speckle pattern, which contains almost all the spatial information and spectral information of the objects. Although various methods have been…

Optics · Physics 2019-02-04 Lei Zhu , Jietao Liu , Lei Feng , Chengfei Guo , Tengfei Wu , Xiaopeng Shao

We investigate linear resonant absorption by a dense ensemble of molecules confined to a subwavelength layer in two geometries: (i) a free-standing film in homogeneous space and (ii) the same film placed at a controlled distance from a…

Optics · Physics 2026-04-14 Zeyu Zhou , Maxim Sukharev , Abraham Nitzan , Joseph E. Subotnik

We present accurate optical spectra of semiconductors and insulators within a pure Kohn-Sham time-dependent density-functional approach. In particular, we show that the onset of the absorption is well reproduced when comparing to…

Materials Science · Physics 2020-03-18 Sarah Cavo , J. A. Berger , Pina Romaniello

Diffraction limit is manifested in the loss of high spatial frequency information that results from decay of evanescent waves. As a result, conventional far-field optics yields no information about an object's subwavelength features. Here…

Optics · Physics 2012-01-24 Leonid Alekseyev , Evgenii Narimanov , Jacob Khurgin

We characterize the optical response of a three-level atom subjected to an incoherent pump and continuously illuminated with a weak, quasi-resonant probe field. To this end, we apply a wavefunction approach based on QED Hamiltonian…

Quantum Physics · Physics 2021-10-27 Manuel Donaire

Simple yet accurate results for radiative transfer in layered media with discontinuous refractive index are obtained by the method of K-integrals, originally developed for neutron transport analysis. These are certain weighted integrals…

Optics · Physics 2016-01-05 Adrian C Selden

We propose a novel approach that jointly removes reflection or translucent layer from a scene and estimates scene depth. The input data are captured via light field imaging. The problem is couched as minimizing the rank of the transmitted…

Computer Vision and Pattern Recognition · Computer Science 2015-06-16 Qiaosong Wang , Haiting Lin , Yi Ma , Sing Bing Kang , Jingyi Yu

A linear scattering problem for which incoming and outgoing waves are restricted to a finite number of radiation channels can be precisely described by a frequency-dependent scattering matrix. The entries of the scattering matrix, as…

Optics · Physics 2022-06-29 Hongyao Wu , Lijun Yuan , Ya Yan Lu

We propose a new method for calculating reflection and transmission coefficients for an arbitrarily polarized electromagnetic plane wave incident on a one-dimensional dielectric medium of finite thickness and with dielectric permittivity…

Optics · Physics 2022-04-27 N. A. Vanyushkin , A. H. Gevorgyan , S. S. Golik

We report an iterative algorithm to retrieve accurate real space information from gas phase ultrafast diffraction measurements with missing data at low momentum transfer. The algorithm operates in a manner similar to phase retrieval…

Chemical Physics · Physics 2026-02-25 Yanwei Xiong , Nikhil Kumar Pachisia , Martin Centurion

We use the separation of variables and T-matrix methods to calculate the optical properties of homogeneous spheroids with refractive indices from m = 1.3+0.0i up to 3+4i. It is found that the extinction cross-sections for highly absorbing…

Astrophysics · Physics 2016-08-30 N. V. Voshchinnikov , V. B. Il'in , Th. Henning , B. Michel , V. G. Farafonov

We present a new method for deriving UV-through-IR extinction curves, based on the use of stellar atmosphere models to provide estimates of the intrinsic (i.e., unreddened) stellar spectral energy distributions (SEDs), rather than…

Astrophysics · Physics 2008-11-26 Edward L. Fitzpatrick , Derck Massa