2018 Benjamin Franklin Medal in Electrical Engineering presented to Manijeh Razeghi, Sc.D

The Terahertz (THz) frequency region has been quite an elusive portion of the electromagnetic spectrum, even though molecular vibration frequencies of most materials-with their distinct spectroscopic signatures-fall into this frequency domain. Spectroscopic process is based on the principle of monitoring transmission and reflection of electromagnetic waves from material under test, when its natural resonance phenomena matches with this spectra, and relies on availability of tunable high-power frequency sources and sensitive detectors. THz sources have been of great interest for quite some time due to their scientific and engineering applications in sensing, imaging, and telecommunications, with significant societal implications. Of particular interest are data communication of over lOOGb/s using THz frequency for distribution of super-resolution images over distances up to a km. In addition, pathogens and concealed drugs or explosives could be detected using spectroscopy of sealed packages with national security interest. Various techniques have been pursued for the development of THz frequency sources, such as electronics and photonics approaches. Among them are Resonant Tunneling Diode, Traveling Wave Tube, injection-seeded Parametric Oscillator, and Quantum Cascade Lasers (QCL), which are the most attractive. QCLs are versatile light sources with tailorable emitting wavelengths covering the mid-infrared long-infrared (i.e., THz domain) of electromagnetic spectrum. In principle, the electronic approaches suffer from lower efficiency than photonics techniques; particularly, when a QCL active region is designed with strong coupling between the lower lasing levels and injector levels, which results in a large nonlinear susceptibility χ(2), THz emission can be generated within the cavity of QCL with a greater efficiency. Professor Manijeh Razeghi, the 2018 Franklin Medalist in Electrical Engineering and founding director, has demonstrated by minimizing dispersion, frequency combs can be directly emitted from QCL via four-wave mixing with output power of about 1W at room temperature. Leading international scholars are assembled in a symposium dedicated to the technical contributions of Professor Razeghi, for her innovative design of high-power, room-temperature THz sources using nonlinear optics, and for developing the epitaxial manufacturing techniques to produce them.