Federico Capasso en conférence au CRHEA

New Frontiers in Nanophotonics: from Quantum Cascade Lasers to Metaoptics

The key components of Metaoptics are subwavelength-scale patterned  surfaces known as Metasurfaces, which allow complete control of the wavefront of light by local design of the phase, amplitude and polarization. Our work on metasurfaces was initially motivated by a great question from one of my colleagues distinguished atmospheric chemist Jim Anderson. I had joined Harvard  from Bell Laboratories where we had invented ten years earlier (1994) the Quantum Cascade Laser (QCL). Colleagues at Harvard had done major work on the detection of greenhouse gases and other chemicals in the atmosphere using QCLs flown in high altitude planes , research which is revolutionizing atmospheric chemistry.  Jim Anderson asked me if we could make highly collimated QCLs without using external optics, which occupies too much space in a drone, to study the chemistry of high altitude clouds by back scattering. This question motivated us to design mid-infrared QCLs with a flat collimating lens  directly patterned on the laser facet.  Later we sub-wavelength structured the facet of TeraHertz QCLs  for beam shaping. The discovery of the generalized laws of reflection and refraction for metasurfaces followed which opened up the research field of metaoptics. High performance metasurfaces for the visible including high NA metalenses for subwavelength imaging, achromatic lenses, axicons, vortex plates, chiral holograms, ultracompact spectrometers and novel waveplates will be discussed, along with the potential of this technology for a wide range of applications. 

Federico Capasso is the Robert Wallace Professor of Applied Physics at Harvard University, which he joined in 2003 after 27 years at Bell Labs where his career advanced from postdoctoral fellow to Vice President for Physical Research. He pioneered bandstructure engineering of semiconductor heterostructures, including the invention of the quantum cascade laser; investigated Casimir forces using micromechanics and performed the first measurement of the repulsive Casimir force. Recent contributions include wavefront control using metasurfaces including the generalized laws of refraction and reflection and a new class of flat optical components such as high efficiency diffraction limited metalenses in the visible. He is the recipient of the 2016 Balzan prize for Applied Photonics. Other awards include the King Faisal Prize for Science, the IEEE Edison Medal, the American Physical Society Arthur Schawlow Prize, the SPIE Gold Medal, the Rumford Prize of the American Academy of Arts and Sciences, the Franklin Institute Wetherill Medal, the European Physical Society Quantum Electronics Prize, the Materials Research Society Medal, Jan Czochralski Award for lifetime achievement in Materials Science, the IEEE D. Sarnoff Award. He is a member of the National Academy of Sciences, the National Academy of Engineering, the American Academy of Arts and Sciences, the Academia Europaea and a foreign member of the Accademia dei Lincei; he holds honorary doctorates from Lund University, University Paris-Diderot and University of Bolog.

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