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Sreekanth K, ElKabbash M, Medwal R, Zhang J, Letsou T, Strangi G, Hinczewski M, Rawat RS, Guo C, Singh R. Generalized Brewster Angle Effect in Thin-Film Optical Absorbers and Its Application for Graphene Hydrogen Sensing. ACS PHOTONICS 2019; 6:1610-1617. [PMID: 31355301 PMCID: PMC6646958 DOI: 10.1021/acsphotonics.9b00564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Indexed: 06/10/2023]
Abstract
The generalized Brewster angle (GBA) is the incidence angle at polarization by reflection for p- or s-polarized light. Realizing an s-polarization Brewster effect requires a material with magnetic response, which is challenging at optical frequencies since the magnetic response of materials at these frequencies is extremely weak. Here, we experimentally realize the GBA effect in the visible using a thin-film absorber system consisting of a dielectric film on an absorbing substrate. Polarization by reflection is realized for both p- and s-polarized light at different angles of incidence and multiple wavelengths. We provide a theoretical framework for the generalized Brewster effect in thin-film light absorbers. We demonstrate hydrogen gas sensing using a single-layer graphene film transferred on a thin-film absorber at the GBA with ∼1 fg/mm2 aerial mass sensitivity. The ultrahigh sensitivity stems from the strong phase sensitivity near the point of darkness, particularly at the GBA, and the strong light-matter interaction in planar nanocavities. These findings depart from the traditional domain of thin films as mere interference optical coatings and highlight its many potential applications including gas sensing and biosensing.
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Affiliation(s)
- Kandammathe
Valiyaveedu Sreekanth
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
- Centre
for Disruptive Photonic Technologies, The
Photonic Institute, 50
Nanyang Avenue, Singapore 639798
| | - Mohamed ElKabbash
- The
Institute of Optics, University of Rochester, 275 Hutchison Road, Rochester, New York 14620, United States
- Department
of Physics, Case Western Reserve University, 10600 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Rohit Medwal
- Natural
Sciences and Science Education, National
Institute of Education, Nanyang Technological University, Singapore 637616
| | - Jihua Zhang
- The
Institute of Optics, University of Rochester, 275 Hutchison Road, Rochester, New York 14620, United States
| | - Theodore Letsou
- Department
of Physics, Case Western Reserve University, 10600 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Giuseppe Strangi
- Department
of Physics, Case Western Reserve University, 10600 Euclid Avenue, Cleveland, Ohio 44106, United States
- CNR-NANOTEC
and Department of Physics, University of
Calabria, 87036 Rende, Italy
| | - Michael Hinczewski
- Department
of Physics, Case Western Reserve University, 10600 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Rajdeep S. Rawat
- Natural
Sciences and Science Education, National
Institute of Education, Nanyang Technological University, Singapore 637616
| | - Chunlei Guo
- The
Institute of Optics, University of Rochester, 275 Hutchison Road, Rochester, New York 14620, United States
| | - Ranjan Singh
- Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
- Centre
for Disruptive Photonic Technologies, The
Photonic Institute, 50
Nanyang Avenue, Singapore 639798
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Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope. Sci Rep 2016; 6:25011. [PMID: 27112966 PMCID: PMC4845020 DOI: 10.1038/srep25011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/08/2016] [Indexed: 11/09/2022] Open
Abstract
Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of specific ions in the solution. It is anticipated that this technique will find use in applications ranging from single-nanoparticles resolved sensing to studying nanoscale fluid-solid interface phenomena.
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Azzam RM. Single-layer antireflection coatings on absorbing substrates for the parallel and perpendicular polarizations at oblique incidence. APPLIED OPTICS 1985; 24:513. [PMID: 18216980 DOI: 10.1364/ao.24.000513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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