Addressing asymmetric Fano profiles on molecular lines in dual-comb spectroscopy

TL;DR

This paper investigates Fano resonance effects in molecular dual-comb spectroscopy, demonstrating how pulse peak power influences asymmetric line shapes and proposing conditions to prevent distortions.

Contribution

It introduces a model combining Fano profiles with Voigt lines to analyze pulse power effects on molecular line asymmetry in dual-comb spectroscopy.

Findings

Fano resonance depends on pulse peak power.

A model estimates Fano phase variation with pulse power.

Conditions to avoid lineshape distortion are derived.

Abstract

Fano resonance in molecular spectroscopy is reported with a dual-comb instrument. The effect is observed as asymmetric absorption lines of H12CN. Pulse chirping conditions in the gas cell are varied to show that Fano resonance is dependent on the pulse peak power. A model adding the Fano profile to Voigt lines is used to estimate Fano phase as a function of pulse peak power. A pulse peak power condition is derived from this analysis to avoid lineshape distortion in pulsed laser experiments.