The Benefits of Dual-Comb Spectroscopy
Dual-comb spectroscopy (DCS) is an advanced spectroscopic technique that deploys two coherent laser sources with discrete, equally-spaced frequency lines. A laser source with this type of spectrum is defined as a frequency comb. The primary benefit of using two frequency combs is that your sample’s spectral response can be quickly assessed on what is known as a tooth-by-tooth basis. But what does this mean in practice?
It is worth digging into the working principles of dual-comb spectroscopy to truly understand the benefits of this pioneering spectroscopic tool.
Dual-Comb Spectroscopy: The Basics
In dual-comb spectroscopy, the idea is to generate an RF spectrum by heterodyning two distinct frequency combs with slightly different repetition rates. The resulting RF comb comprises distinguishable beats between pairs of optical comb teeth.
This works by placing a sample in the optical beam paths of one/both of your coherent laser sources, and recovering the encoded response via heterodyne detection. A rapid photodiode acquires and combines both beams into a characteristic RF comb which is accessible by standard electronics.
Spectra in the optical and RF domains should have an equal correspondence, which means the RF comb can be reliably sampled to produce a digital spectrum with all your relevant spectroscopic data.
Dual-Comb Spectroscopy: The Benefits
Different configurations will yield different information, but dual-comb spectroscopy provides speed, precision, and stability. It can provide rapid, broadband spectral measurements with exceptional resolution and high signal-to-noise ratios. The ability to carry out spectral analysis via RF referencing is also desirable for its ease and simplicity. That simplicity extends into the general architecture of dual-comb spectroscopy too.
Unlike conventional spectroscopic tools, dual-comb spectroscopy requires neither complex moving parts nor gratings to separate optical frequencies and spread the optical spectrum. This function happens digitally in the RF domain. One consequence of this is that both optical paths can be easily implemented on optical fibers or photonic chips, thus significantly reducing the design complexity. This makes dual-comb spectrometers small and robust, with excellent compensation for external perturbations.
Laser Sources for Dual-Comb Spectroscopy
Laser Quantum supplies a broad range of coherent laser sources suitable for dual-comb spectroscopy applications. One of our leading solutions is the powerful 1 Gigahertz (GHz) taccor comb. This is a Ti:sapphire laser with super-continuum generation capabilities and a match dispersion compensation module.
To request more information or a quotation for this or other Laser Quantum products, contact IL Photonics.