EO-based Dual-Comb Source
Electro-optic (EO) frequency combs have experienced a resurgent in the last decade thanks to the technological advances in the photonic instruments. They have been used for different application such as distance measurement and spectroscopy. In our laboratory we have developed an EO-based Dual-Comb Source for subsurface distance measurement and hyperspectral imaging (more info). A cw laser beam at 1555.49584 nm is amplified by an EDFA and split into two arms. Each arm contains two EO phase modulators (PMs) and one EO intensity modulator (IM) in series. The modulators in each arm are driven by two RF signal (at 25.000 GHz and 25.005 GHz). The IMs carve out the linearly chirped part from the heavily phase modulated beam, and a shared spool of ~1 km single mode fiber (SMF) is used to compensate the dispersion and generate optical pulses. The two frequency combs are completely formed after the fiber spool.