Federico Capasso

My research interests cover solid-state physics, physical optics, nonlinear optics, and quantum electronics. As a physicist I have investigated artificial semiconductor materials using the atomic scale control of composition and layer thickness made possible by molecular beam epitaxy. By tailoring the quantum behavior of electrons in nanometer thick layers, my collaborators and I have designed electronic, transport, and optical properties and created a new class of electronic and photonic devices. Examples include atomically abrupt interfaces between materials as electron launching ramps and their application in low-noise photodetectors, electron-resonant tunneling structures for multistate transistors and circuits, electron wave interferometers and coupled-quantum-well pseudomolecules with giant nonlinear optical coefficients for second harmonic generation and frequency mixing. More recently we have demonstrated quantum cascade lasers in which the wavelength can be tailored over a wide range of the infrared spectrum by changing layer thickness.