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Infrared spectroscopy with visible light

Feb 9, 2016 by Author 0 Comments
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Experimental set-up. A continuous-wave laser at 532 nm pumps two nonlinear crystals, where SPDC occurs. The crystals are placed in a vacuum chamber and CO2 is injected into the chamber. The interference pattern of the SPDC from the two crystals is imaged by a lens onto a slit of a spectrograph and recorded by a charge-coupled device (CCD) camera.

Spectral measurements in the infrared optical range provide unique fingerprints of materials, which are useful for material analysis, environmental sensing and health diagnostics1. Current infrared spectroscopy techniques require the use of optical equipment suited for operation in the infrared range, components of which face challenges of inferior performance and high cost. Here, Kalashnikov et al. develop a technique that allows spectral measurements in the infrared range using visible-spectral-range components. The technique is based on nonlinear interference of infrared and visible photons, produced via spontaneous parametric down conversion. The intensity interference pattern for a visible photon depends on the phase of an infrared photon travelling through a medium. This allows the absorption coefficient and refractive index of the medium in the infrared range to be determined from the measurements of visible photons. The technique can substitute and/or complement conventional infrared spectroscopy and refractometry techniques, as it uses well-developed components for the visible range

Reference:

Nature Photonics 10, 98–101 (2016) doi:10.1038/nphoton.2015.252
http://www.nature.com/nphoton/journal/v10/n2/full/nphoton.2015.252.html
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INTERNATIONAL YEAR OF LIGHT 2015

Jan 8, 2015 by admin 0 Comments

On 20 December 2013, The United Nations (UN) General Assembly 68th Session proclaimed 2015 as the International Year of Light and Light-based Technologies (IYL 2015).

This International Year has been the initiative of a large consortium of scientific bodies together with UNESCO, and will bring together many different stakeholders including scientific societies and unions, educational institutions, technology platforms, non-profit organizations and private sector partners.

In proclaiming an International Year focusing on the topic of light science and its applications, the United Nations has recognized the importance of raising global awareness about how light-based technologies promote sustainable development and provide solutions to global challenges in energy, education, agriculture and health. Light plays a vital role in our daily lives and is an imperative cross-cutting discipline of science in the 21st century. It has revolutionized medicine, opened up international communication via the Internet, and continues to be central to linking cultural, economic and political aspects of the global society.

An International Year of Light is a tremendous opportunity to ensure that international policymakers and stakeholders are made aware of the problem-solving potential of light technology. We now have a unique opportunity to raise global awareness of this.

John Dudley, Chairman of the IYL 2015 Steering Committee

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The tunable magnetic-field controlled behaviour of magnetoplasmonic crystals in a wide spectral range has been demonstrated experimentally

Nov 30, 2014 by admin 0 Comments

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Researchers from the Faculty of Physics, Lomonosov Moscow State University, in collaboration with their colleagues from Minsk, Belarus, experimentally studied optical and magnetooptical effects in magnetoplasmonic crystals and demonstrated the tunable magnetic-field controlled behaviour of these crystals in a wide spectral range.

Magnetoplasmonic crystals (MPC) attract much attention due to their unique and pronounced ability to control the light flow. One of the efficient MPC compositions is the combination of a dielectric magnetic film with a thin perforated metal layer on top. It was demonstrated that MPC of such a type supports the resonant excitation of surface plasmon polaritons (SPP) with a relatively long SPP propagation length and reveals a strong magneto-optical response introduced by garnet films. This allows for a magnetic field control over the SPP excitation at the metal/garnet interface. An important point here is that the quality of the interfaces between the adjacent metal and dielectric layers should be smooth and free of defects. This restricts the number of accessible techniques for the MPC fabrication.

In most of the experimental papers methods involving the electron beam lithography were used to make the Au/gold MPC on a gallium gadolinium garnet (GGG) substrate. It was shown that such a structure supports the excitation of the SPP modes localized on two metal surfaces, as well as the waveguide (WG) modes in the dielectric slab. The necessity in use of a template limited the variety of structures that have been studied; besides, the minimal thickness of the gold layer in such MPC was about 70 nm.

In the work of scientists from Physics Department of MSU performed in collaboration with their colleagues from Scientific-Practical Materials Research Centre , Minsk, Belarus, optical and magnetooptical effects in magnetoplasmonic crystals (MPC) were studied. The MPCs were formed by a 1D gold grating on top of a magnetic garnet layer made by a novel method of combined ion-beam etching technique. We demonstrate that the proposed method allows to make high-quality MPC. It is shown that MPC with a 30-40 nm thick perforated gold layer provides an effective excitation of two surface plasmon-polariton modes and several numbers of waveguide modes in the garnet layer. An enhancement of the transversal magneto-optical effect up to the value of 1% is observed for all types of resonant modes that propagate in the magnetic layer, due to magnetic-field control over the mode excitation, which is promising for future photonic devices.

This work has been published in the paper: A. L. Chekhov, V. L. Krutyanskiy, A. N. Shaimanov, A. I. Stognij, T. V. Murzina, “Wide tunability of magnetoplasmonic crystals due to excitation of multiple waveguide and plasmon modes”, Opt. Express 22 (15) 17762-17768 (2014).