Mid-Infrared Photonic Integrated Circuits for Stand-Off Detection of Trace Explosives

Download Project Report (Phase 2, Year 7)

Project Description

This project aims to develop a mid-infrared photonic integrated circuit (MIR-PIC) and use the device for stand-off detection of trace explosives in the solid phase. The proposed MIR-PIC is a mid-infrared (mid-IR) heterodyne receiver comprising a high-performance, mid-IR quantum cascade laser (QCL) with an integrated Schottky barrier diode.

This research addresses the void of high-performance, compact technologies capable of measuring the phase and amplitude of mid-IR light that has interacted with a sample under test. This semiconductor transceiver operates by mixing light scattered off the sample under test and coupled back into the QCL waveguide with the internal field of the waveguide. Changes in the phase and amplitude of the scattered light are detected by measuring the voltage over the integrated diode.

Compared to existing optical stand-off detection technologies, there is no need for an external detector or optics, as the entire sensor operates at room-temperature, and the sensitivity and detection limits are anticipated to improve by orders of magnitude. The proposed MIR-PIC is ultra-compact (~5 mm x 300 mm) and low-cost, making it appropriate for commercial-scale production and it can be integrated into large format arrays for imaging. Single devices will enable rapid stand-off detection of explosives, and arrays of these devices will enable imaging with phase, amplitude, and spectral content for improved detection.

The MIR-PIC represents a fundamentally new type of mid-IR semiconductor transceiver that will enable phase- and amplitude-sensitive imaging in the mid-IR via an ultra-compact device. This research will have significant impact on the Department of Homeland Security (DHS) enterprise due to the complementary sensing and imaging modalities the MIR-PICs enable, as well as the low-cost, small footprint, and improved sensitivity of these devices.

Ultimately, the sensors can be used for detecting explosives residues on skin, clothing, personal items (travel bags, briefcases, etc.), containers, vehicles, and other substrates.  Additionally, a myriad of other fields, including medicine, drug enforcement, and environmental monitoring, will also benefit.



Sensitive, stand-off detection could have a transformative impact on the detection of explosives by enabling widespread screening of individuals, vehicles, and objects. The high sensitivity could enable the use of these devices as a primary or confirming sensor, and the ultra-compact footprint could enable handheld deployment.
Year 4 Annual Report
Project Leader
  • Anthony J. Hoffman
    Assistant Professor
    University of Notre Dame

Students Currently Involved in Project
  • Ahmet Cagri Aydinkarahailoglu
    University of Notre Dame