 Mid-Infrared Optical Coherence Tomography System using a Room Temperature Quantum Cascade Superluminescent Emitter Ahmed Musse, Deborah Varnell, Mei Chai Zheng, Nyan Aung, Germano Penello, and Claire Gmachl Department of Electrical Engineering, Princeton University, Princeton, NJ, 08644, USA

Motivation  OCT systems provide us with a great imaging technique, allowing us to create cross-sectional images of biological tissues, similar to ultrasounds. However, OCT systems are typically non-invasive and give structural information within tissue.

Approach  We decided to use a 5 μm Quantum Cascade Superluminescent (QCSL) emitter that operates at room temperature as our source for our OCT system.  The device maintains low coherence providing better optical resolution than typical QCLs that operate at low temperatures.

Design  To create the OCT system we needed to develop a model that represented the Michelson interferometer.

Results  Our OCT system is capable of producing interferograms using a movable mirror and a another sample, in this case it is simply a gold coated mirror.

Future Work  Future work includes testing the OCT setup with a ZnSe window placed in the sample arm to measure the thickness of the window.  Eventually, biological tissue may be placed in the sample arm and scanned to develop a cross-sectional image.

Summary/Experience  Aligning an IR laser can be tedious. Persistence is key!  Gained a further understanding of Quantum Cascade Lasers and their applications  Gave an insight on prospective research opportunities post- graduation  It was great to be part of something innovative!