Optical sensing at long wavelengths presents significant opportunities and significant challenges. The longwave infrared and terahertz ranges are renowned for their potential to sense molecules in a variety of contexts such as high-speed chemical imaging, disease detection, and environmental monitoring; however, their promise has yet to be fulfilled due to a lack of compact broadband sources and low-loss integrated photonics platforms. The most important sensing challenges require extremely wideband sources to achieve specificity and selectivity, but to date, there are no technologies that are compact, bright, and broadband.
In this talk, I will discuss some of the work of my group that seeks to address this grand challenge. First, I will discuss our development of quantum cascade laser-based frequency combs, light sources that fill the gap between broadband incoherent sources and lasers. I will showcase how we created the first combs in the terahertz range, how they can be engineered to achieve octave-spanning operation, and how they can be used in exciting new compact sensing applications. I will also discuss how our experimental investigations of these combs led to my discovery of a new fundamental comb state that manifests in almost any laser at any wavelength, acting as a mirror image of the classical soliton. Next, I will delve into our development of ultra-low-loss platforms for long wavelengths based on hybrid photonic integration, which allowed us to create optical resonators in the longwave infrared with quality factors 100 times better than the state-of-the-art. This approach is fully wavelength-scalable and allows for the first efficient nonlinear optics at long wavelengths, serving as a foundational element for future applications in quantum sensing. I will then shift gears and discuss our creation of ptychoscopy, a new sensing modality that allows for ultra-precise measurements of optical spectra. This measurement enables the measurement of remote signals with quantum-limited frequency resolution over the entire bandwidth of a comb, for the first time allowing incoherent spectra to be characterized with the precision techniques of combs. Lastly, I will provide a glimpse into the future directions of my lab in the areas of quantum optoelectronics, nonlinear optics, and novel photonic computing.
David Burghoff is an Assistant Professor at Notre Dame, where his lab blends photonics with quantum devices to develop novel sensing and computing modalities. Prior to this, he was a postdoctoral fellow and research scientist at the Massachusetts Institute of Technology, where he led a team working in DARPA’s SCOUT program. He also received his Ph.D. from MIT, where he won the J.A. Kong Award for MIT’s Best Electrical Engineering Thesis. He is widely recognized as a leader in his field, having co-chaired the 2022 and 2020 International Quantum Cascade Laser School and Workshop, and he was one of only five faculty nationally named as a 2022 Moore Inventor’s Fellow. His other awards include the ONR Young Investigator Program Award, the NSF CAREER Award, the AFOSR Young Investigator Program Award, and the Intelligence Community Postdoctoral Fellowship.