Coherently averaged dual-comb spectroscopy with a low-noise and high-power free-running gigahertz dual-comb laser

We present a new type of dual optical frequency comb source capable of scaling applications to high measurement speeds while combining high average power, ultra-low noise operation, and a compact setup. Our approach is based on a diode-pumped solid-state laser cavity which includes an intracavity biprism operated at Brewster angle to generate two spatially-separated modes with highly correlated properties. The 15-cm-long cavity uses an Yb:CALGO crystal and a SESAM as an end mirror to generate more than 3 W average power per comb, below 80 fs pulse duration, a repetition rate of 1.03 GHz, and a continuously tunable repetition rate difference up to 27 kHz. We carefully investigate the coherence properties of the dual-comb by a series of heterodyne measurements, revealing several important features: (1) ultra-low jitter on the uncorrelated part of the timing noise; (2) the radio frequency comb lines of the interferograms are fully resolved in free-running operation; (3) we validate that through a simple measurement of the interferograms we can determine the fluctuations of the phase of all the radio frequency comb lines; (4) this phase information is used in a post-processing routine to perform coherently averaged dual-comb spectroscopy of acetylene (C2H2) over long timescales. Our results represent a powerful and general approach to dual-comb applications by combining low noise and high power operation directly from a highly compact laser oscillator

Dual-comb laser enables broadband detection of optical anisotropies

The measurement of optical anisotropies is widely employed in many application fields, such as material and biomedical sciences. Such spectro- scopic method monitors the polarization state alterations after the interaction be- tween matter and different states of polarized light. Here, we use a newly developed single-cavity dual-comb laser to demonstrate proof-of-principle polarization-resolved measurements. We detect the signals resulting from the heterodyne mixing of the two combs. The interferograms encode the information about the polarimetric prop- erties of samples at kHz rate. Our results complement earlier work with similar single-cavity dual-comb lasers demonstrating pump-probe sampling, and pave the way for a new platform for multimodal sensing

Spatially-multiplexed tunable dual-comb optical parametric oscillator at 250 MHz

We demonstrate a spatially-multiplexed dual-comb 250-MHz OPO from a single linear cavity. The adjustable repetition-rate difference is 4.1 kHz. Each idler comb has >200-mW average power at 3.5 μm with 30 nm bandwidth. The OPO is wavelength-tunable from 1.36 μm to 1.7 μm and 2.9 μm to 4.17 μm. © 2022 The Author(s

Dual-comb laser enables broadband detection of optical anisotropies

The measurement of optical anisotropies is widely employed in many application fields, such as material and biomedical sciences. Such spectroscopic method monitors the polarization state alterations after the interaction between matter and different states of polarized light. Here, we use a newly developed single-cavity dual-comb laser to demonstrate proof-of-principle polarization-resolved measurements. We detect the signals resulting from the heterodyne mixing of the two combs. The interferograms encode the information about the polarimetric properties of samples at kHz rate. Our results complement earlier work with similar single-cavity dual-comb lasers demonstrating pump-probe sampling, and pave the way for a new platform for multimodal sensing