Femtosecond laser-written waveguides and couplers for integrated mid-infrared photonic devices

Virtually every molecule can uniquely be identified by a series of characteristic mid-infrared (IR) absorption lines, thus commonly referred to as the molecule's spectral fingerprint. A-priori unknown substances can therefore be detected with exceptional high selectivity by measuring a sample's response to illumination with broadband mid-infrared light [1]. Consequently, potential applications of mid-IR spectroscopy are vast and are ranging from airport security screening and non-invasive breath analysis to medical imaging and the detection of chemical warfare agents and toxic industrial chemicals, to only name a few. However, the main roadblock for the widespread adoption of this powerful technique is the current lack of integrated miniaturised components that are needed to realise field-deployable mid-IR spectral fingerprinting systems.