Abstract

Optical frequency combs (OFCs) have led to an impressive number of achievements, including multi-heterodyne spectroscopy [1]. Mode-locked OFCs have been widely used due to their exceptional spectral bandwidth, but they usually require sophisticated locking methods to control the free spectral range (FSR) and the absolute frequency of the comb. A promising alternative is provided by electro-optic OFCs, where multiple mutually coherent sidebands are generated by intensity and/or phase modulation of a single stable CW laser. The comb FSR is easily reconfigurable by changing the frequency of the modulation signals. However the number of lines is typically limited to ~10s. This quantity can be increased to 100s but at the expense of conducting spectral broadening by light propagation through a nonlinear fiber [2, 3]. Alternatively, pseudo-random EO phase modulation leads to the generation of hundreds of mutually coherent lines, but then the comb bandwidth is limited to a few GHz [4].

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