Active nonlinear mid-infrared photonics

Abstract

Photonic integration is transforming industries from long-haul fiber communication, data cen- ter interconnects, photonic signal proccessing, and quantum optics. These applications define the operating wavelength range for the photonic integrated circuit components, which is in the near-infrared and the visible. The mid-infrared range (4 – 12 μm), despite its importance for spec- troscopy applications, yet lags behind in terms of development of integrated photonic components. In this thesis I lay out a path towards filling this gap and demonstrate experimental prototypes for the future mid-infrared integrated photonic devices — modulators, pulse generators, frequency comb sources, filters, amplifiers, phase shifters. All components are waveguide-based and incorpo- rate an optical amplifying medium in the waveguide core, which both serves as a source of an optical nonlinearity, and provides for tunability via electrical pumping. Such devices can be readily mass produced at industrial laser foundries as their implementation relies entirely on standard fabrication protocols and on a generic active region design. While devices in this thesis operate at 8 μm, shown approach generalizes across the entire mid-infrared utilizing the quantum cascade laser bandstruc- ture engineering paradigm, and, potentially, to the near-infrared, using other semiconductor gain media with fast recovery, such as interband cascade, quantum well, quantum dot, and quantum dash.