A 99.9986% reflectance crystalline coating at 4.45 µm for mid-infrared cavity-enhanced sensing

  • Gar-Wing Truong (Speaker)
  • Lukas W. Perner (Contributor)
  • Georg Winkler (Contributor)
  • Seth B. Cataño-Lopez (Contributor)
  • Catherine Nguyen (Contributor)
  • David Follman (Contributor)
  • Heckl, O. H. (Contributor)
  • Garrett D. Cole (Contributor)

Activity: Talks and presentationsTalk or oral contributionScience to Science


High-precision trace gas sensing using optical enhancement cavities relies on low-loss mirror technologies. Coatings in the visible and near-infrared have achieved optical losses below 2 parts-per-million (ppm). However, such advancements have been lacking in the mid-infrared (~3 μm to ~8 μm). Here we will discuss the production and characterization of substrate-transferred monocrystalline Bragg mirrors (GaAs/AlGaAs on curved Si substrates) exhibiting a finesse >200,000 at 4.45 μm (13.60 ppm of total loss, with excess optical loss of 4.2 ppm). This represents the first demonstration of mid-infrared supermirrors with simultaneously the highest finesse and lowest losses achieved in this spectral region.
Period3 May 2023
Event titleSPIE Defense + Commercial Sensing: Next-Generation Spectroscopic Technologies XV
Event typeConference
Conference number12516
LocationOrlando, United States, FloridaShow on map
Degree of RecognitionInternational


  • Crystalline mirrors
  • Distributed Bragg reflectors
  • Gas sensing
  • Precision Spectroscopy