Lasers, Optics & Photonics

Biography

Biography: Simone Borri

Abstract

Molecular precision spectroscopy opens new perspectives on tests of fundamental laws of physics and fundamental constants variation. The mid infrared (IR) is a key region for molecular spectroscopy and the eff orts towards the development of versatile, spectrally pure and tunable coherent sources in this region have been constantly growing in the last decade. During the last years, we have made signifi cant eff orts in the development of metrological-grade coherent sources. Here, we present our more recent work based on two diff erent approaches, both involving frequency-stabilized mid-IR quantum cascade lasers (QCLs). The first approach is based on crystalline fl uoride whispering-gallery-mode resonators. Th ese devices have started to show their full potential for mid-IR photonics in the last two years. Th ey demonstrated record Q-factors (~108 around 4.5 μm) and a further increase is expected with the improvement of materials and fabrication techniques. We successfully tested a compact apparatus for high-precision spectroscopy based on mid-IR QCLs locked to fl uoride resonators. The  low sensitivity of the resonator to environmental noise is one of the strengths of this approach, leading to good stability levels even over long timescales (10 kHz on 1s timescale). The second approach is based on the combination of a mid-IR QCL and a metrological-grade source based on diff erence frequency generation using an OP-GaP crystal. Here we take advantage of the optical reference delivered from the Italian national laboratory for metrological research (INRIM) through a stable and ever-growing fi bre network. The is combination allows for mW-level radiation that covers, in principle, the entire molecular fi ngerprint region, with linewidths at kHz level and with a phase-noise compatible with a 10−14 shortterm instability.