Magneto-optic-plasmonic Surface Plasmon Resonance

Magneto-optic-plasmonics (MOP) is a relatively new class that merges the three sub-fields: optics, magnetics, and plasmonics of science. The main ingredients of MOP material are ferromagnetic and ferromagnetic oxide materials like Fe, Co, Ni, magnetite, etc. where any change in permittivity tensor is conveyed by the presence of an applied external force or a magnetic field. The permittivity tensor is also dependent on the frequency of the incident optical radiation.

Magneto-optic materials can be used in various areas. These include determination of dynamic studies of film growth, detection of magnetic impurities, average free carrier effective mass, MO filters, atomic line filters, field sensors, memories, modulators and integrated optoelectronic devices like optical circulators, switches and isolators. The drives using thermomagnetic recording and magnetic recording also use MO materials. Some other fields where MO materials are used include spintronics and MO microscopy. The most recent application is the biomedical field where efforts are in process to develop a biosensor which is the most sensitive to date.

The discovery of magneto-optic effects in metals and dielectric is not new (it was very first discovered and demonstrated by Michael Faraday in 1845). However, the application of MO in spintronics and recording have been found only in the 1990s. The importance of magneto-optic in sensing and imaging has emerged only in the last decade.

The recent application of magnetic-field on bio-sensing is shown in the picture below. The picture demonstrates a right-angled isosceles prism, indexed matching liquid, lenses, buffer layer, optical laser source, a substrate with transducer/sample and a photodetection (PD) system.

The future of magneto-plasmonic based nanostructures is extremely bright. These nanostructures display exceptional properties like high sensitivity, strong enhancement of electromagnetic fields, the possibility of obtaining high photothermal conversion efficiencies, large signal to noise ratio and rich spectral responses at applied magnetic fields, makes them outstanding, unique and sought for material for various applications.

Applications of Magnetoplasmonics:

The application of magnetoplasmonics has a vast range of possibilities in number of fields including clinical therapy, biophysics, diagnostics, bio-imaging, environmental monitoring, biophysics, chemical and biological sensing, ultra-fast molecular sensing for early disease detection, magneto-plasmon-enabled photo-thermal therapy, magneto-plasmon-assisted laser welding, plasmon-assisted photo-acoustic imaging and magneto-plasmon-enhanced spectroscopies, like SERS for magneto-plasmonic structures and fields are expected to extend the production of energy and in exploration of space as well.

Some other additional areas where magnetoplasmonic-based devices and structures can be used are magneto-plasmon based isolators, photo-detectors, harvesting and conversion of solar energy along with the coupling of magneto-plasmons to chemical reactions in order to achieve high selectivity and activity for energy saving, switching and sensing and tuning of magneto-optical properties at the femtosecond speed.

Some other highly promising areas where the potential of this technology can be fully utilized include the development of bio-nanomagnetic and magetoplasmonic bioengineering, high-performance magnetronic devices and green energy, biomedicine and biology to mention a few.

Conrad has done extensive research on Magneto-optic-plasmonics and his paper can be accessed Here

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