Configuration for IRis-core dual-comb source: Spectral range: 1035 cm−1 to 1085 cm−1; Repetition rate: ≈7.417 GHz; Difference in repetition rates: 2.1 MHz; Average output optical power: ≥100 mW; Attenuation: ~10x with neutral density filters; Optical path: reference and probe paths focused by off-axis parabolic mirrors (focal length 25.4 mm)