The unique structure of frequency combs, light sources whose lines are perfectly evenly-spaced, allows for new avenues in the measurement of optical signals. Terahertz quantum cascade laser based combs are attractive options for comb-based sensing, as they have low repetition rates and large powers per comb tooth. We will discuss how computational techniques used in concert with these combs can be used to measure the spectrum of an unknown light source|both phase and amplitude. In particular, we will discuss (a) how frequency combs can be used to recover the spectrum of arbitrary optical signals, even incoherent ones, (b) how Fourier-domain methods can be used to retrieve the phase of arbitrary combs, and (c) how terahertz combs can be used to perform high-speed, high-performance spectroscopy.
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