المؤلفون: Götte, Jörg B, O'Holleran, Kevin, Preece, Daryl, Flossmann, Florian, Franke-Arnold, Sonja, Barnett, Stephen M, Padgett, Miles J

المصدر: Optics Express. 16(2)

مصطلحات موضوعية: Quantum Physics, Physical Sciences, Computer Simulation, Light, Models, Theoretical, Quantum Theory, Radiation Dosage, Radiometry, Scattering, Radiation, Angular momentum, Data processing, Gaussian beams, Quantum theory, Fractional orbital angular momentum, Light beams, Spiral phase plate, Vortex structure, Wave propagation, article, computer simulation, light, methodology, quantum theory, radiation dose, radiation scattering, radiometry, theoretical model, Optical Physics, Electrical and Electronic Engineering, Communications Technologies, Optics, Communications engineering, Electronics, sensors and digital hardware, Atomic, molecular and optical physics

الوصف: Light emerging from a spiral phase plate with a non-integer phase step has a complicated vortex structure and is unstable on propagation. We generate light carrying fractional orbital angular momentum (OAM) not with a phase step but by a synthesis of Laguerre-Gaussian modes. By limiting the number of different Gouy phases in the superposition we produce a light beam which is well characterised in terms of its propagation. We believe that their structural stability makes these beams ideal for quantum information processes utilising fractional OAM states.

وصف الملف: application/pdf

الوصول الحر: https://escholarship.org/uc/item/63p0w2b9Test

المؤلفون: Fredenberg, Erik, PhD, 1979, Cederström, Björn, Nillius, Peter, Ribbing, Carolina, Karlsson, Staffan, Danielsson, Mats

المصدر: Optics Express. 17(14):11388-11398

مصطلحات موضوعية: X-ray optics, Diffractive lenses, Refractive lenses, Filters, Medical x-ray imaging, Radiation, Wave propagation, TECHNOLOGY, Engineering physics, Optical physics, TEKNIKVETENSKAP, Teknisk fysik, Optisk fysik, MEDICINE, Physiology and pharmacology, Radiological research, Radiological physics, MEDICIN, Fysiologi och farmakologi, Radiologisk forskning, Radiofysik, Other engineering physics, Övrig teknisk fysik, Other technology, Medical engineering, Övriga teknikvetenskaper, Medicinsk teknik

الوصف: We present an experimental and theoretical evaluation of an x-ray energy filter based on the chromatic properties of a prism-array lens (PAL). It is intended for small-scale applications such as medical imaging. The PAL approximates a Fresnel lens and allows for high efficiency compared to filters based on ordinary refractive lenses, however at the cost of a lower energy resolution. Geometrical optics was found to provide a good approximation for the performance of a flawless lens, but a field-propagation model was used for quantitative predictions. The model predicted a 0.29 ΔE/E energy resolution and an intensity gain of 6.5 for a silicon PAL at 23.5 keV. Measurements with an x-ray tube showed good agreement with the model in energy resolution and peak energy, but a blurred focal line contributed to a 29% gain reduction. We believe the blurring to be caused mainly by lens imperfections, in particular at the periphery of the lens.

وصف الملف: print

الوصول الحر: https://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11635Test
https://doi.org/10.1364/OE.17.011388Test
http://www.opticsinfobase.org/DirectPDFAccess/347EE40C-BDB9-137E-C8136239390C793B_182999.pdf?da=1&id=182999&seq=0Test

المؤلفون: Osamu Kojima, Matthew J. Steer, Takashi Kita, Richard A. Hogg, Kanta Sakaue

المصدر: Optics Express. 29(15):24387-24395

مصطلحات موضوعية: Materials science, Condensed Matter::Other, business.industry, Terahertz radiation, Exciton, Physics::Optics, Interference (wave propagation), Laser, Atomic and Molecular Physics, and Optics, Terahertz spectroscopy and technology, law.invention, Optics, law, Attenuation coefficient, Atomic physics, business, Excitation, Quantum well

الوصف: Intense terahertz-wave emission in the higher frequency region can result in various applications such as terahertz spectroscopy and ultrafast data communication. In this study, an increase in terahertz waves by the overlap of exciton states in different quantum wells and spectroscopic demonstration are reported. The excitation energy dependence of signal intensity shows the effect of the overlap. The signals measured under the condition of square dependence of intensity on the excitation power indicate interference with the periods corresponding to the laser energy difference. Furthermore, the absorption coefficient of the transparent sheet is obtained at specific frequency. These results indicate that the generation of intense terahertz waves at various frequencies using excitons is possible and that difference frequency mixing is a useful terahertz-wave source.

وصف الملف: application/pdf

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::97a3e4ed8f0ae59329ad78fb1afa7c4dTest
https://hdl.handle.net/20.500.14094/90008469Test

المؤلفون: Jeremy M. Coupland, Richard Leach, Peter J. de Groot, Matthew Thomas, Rong Su

المصدر: Optics express. 29(22)

مصطلحات موضوعية: Physics, business.industry, Physics::Optics, 02 engineering and technology, Interference (wave propagation), 01 natural sciences, Atomic and Molecular Physics, and Optics, Numerical aperture, 010309 optics, Interferometry, 020210 optoelectronics & photonics, Optics, Tilt (optics), 0103 physical sciences, Coherence scanning interferometry, 0202 electrical engineering, electronic engineering, information engineering, Astronomical interferometer, Specular reflection, business, Physics::Atmospheric and Oceanic Physics, Coherence (physics)

الوصف: The capability of optical surface topography measurement methods for measurement of steep and tilted surfaces is investigated through modelling of a coherence scanning interferometer. Of particular interest is the effect on the interference signal and measured topography when tilting the object at angles larger than the numerical aperture slope limit (i.e. the specular reflection limit) of the instrument. Here we use theoretical modelling to predict the results across a range of tilt angles for a blazed diffraction grating. The theoretically predicted interference patterns and surface height measurements are then verified directly with experimental measurements. Results illustrate the capabilities, limitations and modelling methods for interferometers to measure beyond the specular reflection limit.

وصف الملف: PDF

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::090fa0524c9280d0427a8917f7649c5eTest
https://pubmed.ncbi.nlm.nih.gov/34809031Test

المؤلفون: Yutao Feng, Caixun Bai, Wenfei Zhang, Xu Yixuan, Jianxin Li

المصدر: Optics express. 29(23)

مصطلحات موضوعية: Physics, Birefringence, business.industry, Fast Fourier transform, Polarimetry, Physics::Optics, Polarization (waves), Interference (wave propagation), Atomic and Molecular Physics, and Optics, symbols.namesake, Optics, Fourier transform, symbols, business, Shearing interferometer, Optical path length

الوصف: A static full-Stokes Fourier transform imaging spectropolarimeter incorporating a liquid-crystal polarization modulator (LPM) and birefringent shearing interferometer (BSI) is reported. It can decode the polarization information at each wavelength along the spatial dimension of a two-dimensional data array. The LPM has a high-speed time-division architecture and employs two ferroelectric liquid crystals and two wave plates to produce four polarization states, providing full-Stokes polarimetric information with a high signal-to-noise ratio. The BSI comprises two birefringent crystal plates and generates an optical path difference with good linear distribution for broadband interference, allowing a fast and high-precision spectral recovery. The optimized design of LPM and BSI are introduced in detail. Subsequently, the signal reconstruction is verified through simulations and experiments. The proposed scheme is highly efficient, exhibits a higher spectral resolution, and constitutes a compact technical approach to realize high-dimensional optical measurement.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b0cf9e1f9a04acc560dc018796b3e545Test
https://pubmed.ncbi.nlm.nih.gov/34808912Test

المؤلفون: Yu Li, Sun Jinhai, Jielin Shi, Zhao Yarui, Hongbin Ding, Sun Xinxue, Yongqiang Liu, Ding Wu, He Cai, Chao Zengming, Hongcheng Yin, Zhu Xianli, Wenqi Lu, Zhang Xutao, Zheng Yan

المصدر: Optics express. 29(22)

مصطلحات موضوعية: Materials science, business.industry, Wave propagation, Thomson scattering, Terahertz radiation, Physics::Optics, Plasma, Atomic and Molecular Physics, and Optics, Finite element method, Terahertz spectroscopy and technology, Computer Science::Robotics, Optics, Physics::Plasma Physics, Inductively coupled plasma, business, Terahertz time-domain spectroscopy

الوصف: Firstly, the electron density distribution of inductively coupled plasma (ICP) is measured by laser Thomson scattering (TS) method and the features of the ICP under the same experimental conditions are simulated by finite element method (FEM). The simulated results are in good agreement with the experimental results, which verifies the accuracy of the ICP generation simulation model. Secondly, the propagation characteristics of terahertz wave in ICP are measured by terahertz time domain spectroscopy (THz-TDS) and calculated by FEM according to the electron density distribution of ICP simulated in the first step above. The high consistency between the experimental and simulation results of terahertz wave propagation characteristics in ICP further proves the accuracy of terahertz wave transmission model in plasma and the feasibility of joint simulation with ICP generation simulation model.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3be5d5409118ba6a093503933de6c6c9Test
https://pubmed.ncbi.nlm.nih.gov/34809009Test

المؤلفون: Yuanyuan Zhao, Pei Zhang, Zehong Chang, Xiaoting Huang, Xiaoli Wang

المصدر: Optics express. 29(21)

مصطلحات موضوعية: Physics, business.industry, Quantum key distribution, Interference (wave propagation), Measure (mathematics), Atomic and Molecular Physics, and Optics, Computational physics, Optics, Transformation (function), Light beam, business, Optical vortex, Intensity (heat transfer), Topological quantum number

الوصف: Perfect optical vortex beams (POV) have attracted considerable attention in many novel applications because they have the advantage of a radial profile that is independent of the topological charge (TC). Nowadays, there are few effective methods to measure both the integer and the fractional TCs of the POV. In this paper, we achieve the precise measurement of arbitrary TCs through the approach of dynamic angular double slits (ADS), which performs the transformation from the POV to the interference intensity patterns at the angular bisector direction of the ADS. The information of the TC can be obtained from the periodically changing interference pattern. The deviation is less than 2% by comparing the theoretical values with the fitting results, therefore the detection method is effective and reasonable.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::34212197a917dd938e80bc429ee8ac41Test
https://pubmed.ncbi.nlm.nih.gov/34809117Test

المؤلفون: Yonghua Mao, Peizhen Qiu, Dawei Zhang, Chunyan Bai

المصدر: Optics express. 29(23)

مصطلحات موضوعية: Physics, business.industry, Physics::Optics, Near and far field, Interference (wave propagation), Surface plasmon polariton, Chirality (electromagnetism), Atomic and Molecular Physics, and Optics, Optics, Surface wave, Electric field, Near-field scanning optical microscope, business, Circular polarization

الوصف: The determination of chirality of circularly polarized light (CPL) is of great significance to the development of various optical techniques. In this paper, a miniature circular polarization analyzer (CPA) based on surface plasmon polariton (SPP) interference is proposed. The proposed CPA consists of a micron scale long sub-wavelength slit and two groups of spatially arranged periodic sub-wavelength rectangular groove pairs, which are etched in a metal layer. Under the illumination of a CPL with a given chirality, the proposed CPA is capable of forming SPP-mediated interference fringes with different periods in far field. The chirality of CPL can be directly and quantitatively differentiated by the frequency value of the far field SPP-mediated interference fringes. Different from the existing SPP-based CPAs, the proposed CPA can directly image the chirality information in far field, avoiding near-field imaging of the SPP field.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a47f76a19a2546aa9fcbf4a7f3d9d235Test
https://pubmed.ncbi.nlm.nih.gov/34808854Test

المؤلفون: Xiaopeng Xu, Yu Li, Wei-Ping Huang

المصدر: Optics express. 29(22)

مصطلحات موضوعية: Physics, business.industry, Bandwidth (signal processing), CPU time, Interference (wave propagation), Atomic and Molecular Physics, and Optics, Optics, Asynchronous communication, Splitter, Return loss, Electronic engineering, Insertion loss, Power dividers and directional couplers, business

الوصف: The asynchronous double deep Q-learning (A-DDQN) method is proposed to design the multi-mode interference (MMI) power splitters for low insertion loss and wide bandwidth from 1200 to 1650 nm wavelength range. By using A-DDQN to guide hole etchings in the interference region of MMI, the target splitting ratio (SR) can be obtained with much less CPU time (about 10 hours for one design) and more effective utilization of the computational resources in asynchronous/parallel manner. Also, this method can simplify the design by using relatively few holes to obtain the same SR with small return loss.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::430079dd7426a5e082ab4df2b09c6ee2Test
https://pubmed.ncbi.nlm.nih.gov/34809018Test

المؤلفون: Jeremy Teichman

المصدر: Optics express. 29(21)

مصطلحات موضوعية: Wavefront, Diffraction, Physics, business.industry, Physics::Optics, Strehl ratio, Optical power, Interference (wave propagation), Atomic and Molecular Physics, and Optics, Time of flight, Optics, Time domain, business, Coherence (physics)

الوصف: Thin lenses of sufficient diameter and focusing power cannot fully compensate for variation in free-space time of flight to maintain and focus an intact wavefront and instead combine successive wavefronts. The limited temporal coherence of broadband light reduces the effectiveness of such interference. Using effective medium theory and scalar diffraction we exploit time-domain analysis to show that the temporal coherence of illumination imposes hard limits on the performance of thin lenses as measured by the Strehl ratio. These limits apply equally to diffractive optical elements and metalenses.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b1b03dcce1e0c87f47ca8282e7b06bebTest
https://pubmed.ncbi.nlm.nih.gov/34809103Test