Federico Capasso

Who is Federico Capasso?

Federico Capasso, a prominent applied physicist, was one of the inventors of the quantum cascade laser during his work at Bell Laboratories. He is currently on the faculty of Harvard University. He has co-authored over 450 papers, edited four volumes, and holds over 60 US patents.

Federico Capasso received the doctor of Physics degree, summa cum laude, from the University of Rome, Italy, in 1973 and after doing research in fiber optics at Fondazione Bordoni in Rome, joined Bell Labs in 1976. 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 and Vice President of Physical Research. He joined Harvard on January 1, 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 well avalanche photodiodes, heterojunction transistors, memory devices and lasers. He and his collaborators invented and demonstrated the quantum cascade laser . 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. The QCL wavelength can be tailored across a wide range from the mid-infrared to the far infrared by changing the quantum well thickness. 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.