Speaker
Description
Lenses can't normally achieve part-per-million (ppm) level loss because of coating absorption, surface roughness, diffraction, and other field-related effects. While the first three can be mitigated through annealing, super-polish, and substrate diameter control, thin-film coatings, especially on strongly curved substrates, suffer from a position dependent attenuation or “apodization” effect across their aperture. We present a co-design of optimized thin-film coatings over curved apertures to realize ultra-low loss lenses while marginalizing their thermal noise contributions. This design enables applications for advanced laser interferometers with intracavity lenses, low-loss mode-matching for both bulk and integrated photonic squeezers, and others.