Dual Comb Spectroscopy with Mismatched Combs

Dual comb spectroscopy is a high resolution spectroscopic technique, that does not rely on free space optics. It requires two frequency combs which are lasers comprised of equally spaced narrow linewidth lasers. Dual comb spectroscopy can resolve the intensity of individual comb teeth, which is independent of the wavelength of the frequency combs used. Often two matched frequency combs are used because of the mutual coherence and stability required to perform dual comb spectroscopy. This work seeks to design and build an electro-optic frequency comb that has a highly stable mode spacing with a larger bandwidth than other examples in literature. The second frequency comb is a Yb fiber oscillator matched to lasers used in other experiments. These two frequency combs are used to characterize ammonia in a gas cell. These initial steps will lay the groundwork for using dual comb spectroscopy on more complex experiments like transient absorption and 2D spectroscopy.