Computationally-enhanced molecular sensing using optical frequency combs

Air pollution is an increasingly important concern in larger cities and industrial areas.

To date, much attention has been devoted to monitoring of particulate matter (PM), yet sensing of toxic or cancerogenic gas species formed i.e. in combustion of low-quality fuels is still challenging.

The new National Emissions Ceilings (NEC) Directive (2016/2284/EU) has set commitments for member states on several important air pollutants, of which two groups: non-methane volatile organic compounds (NMVOCs), and persistent organic pollutants (POPs) are difficult to monitor using existing electrochemical or laser-based technologies to ensure sufficient sensitivity and selectivity.

To address this need, the objective of this proposal is to develop a novel class of broadband and high-resolution laser spectrometers for open-path atmospheric monitoring.

The instrument will exploit a pair od optical frequency comb (OFC) sources, which operate in the spectroscopically-relevant mid-infrared region where NMVOCs and POPs have their strongest and most unique absorption features.

Unlike all prior attempts, this project aims to advance the field by enabling completely unstabilized operation of the sources using real-time computational signal enhancement referred to as Computationally Enhanced Molecular Sensing with Optical Frequency Combs (CEMOS-OFC).

By generating two mutually coherent OFCs in a shared cavity, the need for complex phase synchronization electronics in dual-comb spectroscopy is eliminated, which paves the way for practical out-of-laboratory measurements of multi-species gas mixtures over open-path channels reaching hundreds of meters corresponding to part-per-million to parts-per-billion sensitivities.

In addition to environmental gas sensing, spectroscopic analysis of simple algae and pharmaceuticals in the mid- to far-infrared region is also proposed.