Novel Nanodevices for Spectroscopy and Nonlinear Optics
One of the next frontiers of integrated photonics is surely represented by the challenge of extending the use of optical techniques to nanometer length scales, overcoming the limit imposed by diffraction, which does not allow focusing light on dimensions smaller than roughly half a wavelength. Metallic nanostructures have proven to be an efficient way to “squeeze” light on such dimensions, significantly enhancing the local field at the same time. This has brought to a
myriad of applications in many fields, including subwavelength optical imaging of nanomaterials and DNA, efficient generation of deep ultraviolet light and the very recent perspective of significantly improving the efficiency of thin-film solar cells. Given this unquestionable interest, we want to develop at INRS-EMT a vigorous research program regarding the exploitation of these concepts in the mid-infrared (mid-IR ~2 – 20 ?m) and terahertz (THz ~20 – 1000 ?m) regions of the electromagnetic spectrum. These spectral ranges are of great interest for spectroscopy, since many molecules exhibit specific vibrational/rotational transitions at these frequencies. In particular, mid-IR spectroscopy gives full access to a rich region of vibrations of molecules that are relevant for both inorganic and organic chemistry, and can as well give information regarding protein structure and folding. THz spectroscopy, instead, is sensitive to rotational transitions of light molecules and vibrations of molecules composed by large functional groups, as it is the case for biological molecules.
In the framework of the present Project, we intend to shed some light on the use of metallic nanostructures for assisting long-wavelength spectroscopies and nonlinear optics. More specifically, we will study: (i) the possibility of employing arrays of “nanoantennas” for enhancing terahertz spectroscopy of biomolecules, in view of some exciting bio-sensing applications; (ii) localized terahertz nonlinear optics mediated by nanoplasmonics, for its fundamental interest and for its possible use in next-generation terahertz nanoelectronic devices; (iii) a novel kind of mid-infrared nanoscope, capable of acquiring chemical maps of surfaces with nanometric resolutions; and (iv) new nanoplasmonic tools for boosting mid-infrared nonlinear optical processes for applications in silicon photonics.
The outcomes of the proposed investigations may have an important impact in biological studies and biosensing, offering a crucial contribution to few-molecule absorption spectroscopy, a field of paramount relevance, for example, in the early diagnosis of diseases. Besides this, the information offered by localized nonlinear experiments at mid-IR and THz frequencies may help understanding unexplored aspects of radiation-matter interaction and could bring to the development of novel nanophotonic devices capable of processing, shaping, and frequency-converting long-wavelength pulses and to deliver them to the nanoscale.
