Optical Frequency Combs Generated by Acousto-Optic Frequency-Shifting Loops

A recirculating loop that includes an acousto-optic frequency shifter (AOFS) constitutes a versatile procedure to generate an optical frequency comb (OFC) from a continuous wave (cw) laser. This scheme, implementable with conventional fiber equipment, is capable of producing spectra composed of at least hundreds of coherent lines using a single-stage system. In this letter, we summarize the method to generate these acousto-optic frequency combs and briefly describe a simple model to optimize their performance. We also overview their main reported applications, paying special attention to those based on the peculiarities exhibited by the optical field at the output of the fiber loop.