UNT Physics Colloquium Presents Dr. David Burghoff

About this event

Nonlinear photonics and comb generation in the mid-infrared and terahertz

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.

Dr. David Burghoff will discuss some of the work of his group that seeks to address this challenge. First, Burghoff will discuss the development of quantum cascade laser-based frequency combs, light sources that fill the gap between broadband incoherent sources and lasers. He will also discuss how the experimental investigations of these combs led to the discovery of a new fundamental comb state that manifests in almost any laser at any wavelength, acting as the phase equivalent of passive modelocking [1], [2], [3]. Next, Burghoff will discuss the recent development of ultra-low-loss platforms for long wavelengths based on hybrid photonic integration, which allowed his team to create optical resonators in the longwave infrared with quality factors 100 times better than the state-of-the-art [4], [5]. 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. Finally, Burghoff will discuss his team's development 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 [6].

[1] D. Burghoff, “Unraveling the origin of frequency modulated combs using active cavity mean-field theory,” Optica, vol. 7, no. 12, pp. 1781–1787, Dec. 2020, doi: 10.1364/optica.408917.

[2] Z. Xiao, M. Roy, C. Dong, Z. Xu, S. Addamane, and D. Burghoff, “Delay-resolved spectroscopy in terahertz photonic circuits,” Npj Nanophotonics, vol. 2, no. 1, pp. 1–7, May 2025, doi: 10.1038/s44310-025-00065-6.

[3] X. Gao, C. Guo, and D. Burghoff, “Mode switching through exceptional points induced by lasing–inversion coupling,” Optica, vol. 13, no. 10, pp. 2118–2125, Oct. 2026, doi: 10.1364/OPTICA.599010. [4] D. Ren, C. Dong, S. J. Addamane, and D. Burghoff, “High-quality microresonators in the longwave infrared based on native germanium,” Nat. Commun., vol. 13, no. 1, Art. no. 1, Oct. 2022, doi: 10.1038/s41467-022 32706-1.

[5] D. Ren et al., “Low-loss hybrid germanium-on-zinc selenide waveguides in the longwave infrared,” Nanophotonics, vol. 13, no. 10, Jan. 2024, doi: 10.1515/nanoph-2023-0698.

[6] D. J. Benirschke, N. Han, and D. Burghoff, “Frequency comb ptychoscopy,” Nat. Commun., vol. 12, no. 1, p. 4244, Jul. 2021, doi: 10.1038/s41467-021-24471-4.