Princeton University

School of Engineering & Applied Science

Integrated mid-infrared photonics: From quantum cascade lasers to suspended silicon-on-insulator waveguides

Arash Sadeghi
Prof. Gmachl
Engineering Quadrangle B327
Wednesday, May 1, 2019 - 3:30pm to 5:00pm


The mid-infrared, covering the wavelength range 3−30 µm (10 − 100 THz) is of particular importance for chemical species detection, since many atmospheric trace gases and liquids have fingerprint spectra in this wavelength range. The atmospheric windows in the wavelength range of 3 − 5 µm and 8 − 12 µm, offer a highly desirable low-loss region for chemical trace gas sensing, high-bandwidth free-space communication, and laser-based advanced defense countermeasures against IR-guided munitions. Leveraging the silicon fabrication protocols for CMOS compatible Si-optical integration, where photonic components are fabricated on a single Si chip, results in improved yield, compactness and lower manufacturing costs due to the economy of scale.

Quantum Cascade (QC) lasers are a promising source of laser radiation in the mid-infrared, operating between ∼ 3 − 300 µm, made possible through advances in bandgap engineering and fabrication techniques. Compact size, wide range of operation and high output power are amongst the many advantages of QC lasers. Narrow-band, high-power operation of QC lasers is particularly desirable in laser-assisted surgery in medicine or defense countermeasures.

We explore solutions for controlling the output spectra of QC lasers through laser cavity design and fabrication. Also discussed is a road map for achieving integration of QC lasers into a silicon-compatible platform, the respective challenges to be overcome and our current progress towards these goals.