In 1984, he was made a distinguished member of technical staff and in 1997 a Bell Labs Fellow. In addition to his research activity, Capasso has held several management positions at Bell Labs, including head of the quantum phenomena and device research department and the semiconductor physics research department (1987–2000) and vice president of physical research (2000–2002). He joined Harvard on 1 January 2003.
He and his collaborators made many wide-ranging contributions to semiconductor devices, pioneering the design technique known as band-structure engineering. He applied it to novel low noise quantum wellavalanche photodiodes, heterojunction transistors, memory devices and lasers. He and his collaborators invented and demonstrated the quantum cascade laser (QCL).[2] Unlike conventional semiconductor lasers, known as diode lasers, which rely on the band gap of the semiconductor to emit light, the wavelength of QCLs is determined by the energy separation between conduction band quantized states in quantum wells. In 1971 researchers postulated that such an emission process could be used for laser amplification in a superlattice.[3] The QCL wavelength can be tailored across a wide range from the mid-infrared to the far infrared by changing the quantum well thickness. The mature technology of the QCL is now finding commercial applications.[4] QCLs have become the most widely used sources of mid-infrared radiation for chemical sensing and spectroscopy and are commercially available. They operate at temperatures in excess of 100°C and emit up to several watts of power in continuous wave.
Capasso's current research in quantum electronics deals with very high power continuous-wave QCLs, the design of new light sources based on giant optical nonlinearities in quantum wells such as widely tunable sources of terahertz radiation based on difference frequency generation and with plasmonics. He and his group at Harvard have demonstrated a new class of optical antennas and plasmonic collimators that they have used to design the near-field and far-field of semiconductor lasers, achieving ultrahigh intensity deep subwavelength size laser spots, laser beams with greatly reduced divergence and multibeam lasers. His group showed that suitably designed plasmonic interfaces consisting of optically thin arrays of optical nano-antennas lead to a powerful generalization of the centuries-old laws of reflection and refraction. They form the basis of "flat optics" based on metasurfaces.
Federico Capasso has made major contributions to the study of quantum electrodynamical forces known as Casimir forces. He used the Casimir effect (the attraction between metal surfaces in vacuum due to its zero point energy) to control the motion of MicroElectroMechanical Systems (MEMS). He demonstrated novel devices (Casimir actuators and oscillators), setting limits to the scaling of MEMs technology and with his collaborators Jeremy Munday and Adrian Parsegian was the first to measure a repulsive Casimir force.[5]
On behalf of the American Physical Society, he was awarded the 2004 Arthur L. Schawlow Prize in Laser Science, endowed by the NEC Corporation, for "seminal contributions to the invention and demonstration of the quantum cascade laser and the elucidation of its physics, which bridges quantum electronics, solid-state physics, and materials science."
SPIE, the international society of optics and photonics, selected Capasso to receive the 2013 SPIE Gold Medal,[7] the highest honor the society bestows.
In addition, the IEEE (Institute of Electrical and Electronics Engineers), the world's largest technical professional organization, named Capasso the recipient of the 2004 IEEE Edison Medal with the following citation, "For a career of highly creative and influential contributions to heterostructure devices and materials."
In 2016 he was awarded the Balzan Prize for Applied Photonics "For his pioneering work in the quantum design of new materials with specific electronic and optical features, which led to the realization of a fundamentally new class of laser, the Quantum Cascade Laser; for his major contributions in plasmonics and metamaterials at the forefront of photonics science and technology". He received the Matteucci Medal in 2019 from the Italian National Academy of Sciences for his invention of the quantum cascade laser.[8]
In 2021 Capasso received the Frederic Ives Medal/Jarus W. Quinn Prize from the Optical Society of America for seminal and wide-ranging contributions to optical physics, quantum electronics and nanophotonics.[9]
Bibliography
Capasso, Federico (2005). Avventure di un designer quantico (in Italian). Di Renzo. ISBN978-88-8323-105-6.
↑Kazarinov, RF, R.F; Suris, RA (1971). "Possible amplification of electromagnetic waves in a semiconductor with a superlattice". Fiz. Tekh. Poluprovodn. 5: 797–800.
↑Donnelly (2010). "Video interview: Federico Capasso on the quantum cascade laser". SPIE Newsroom. doi:10.1117/2.3201004.02.
