Tunable Optical Dual-Comb Experiments Using Silicon Mach- Zehnder Modulators

Dual comb spectroscopy is a technique that simultaneously enables high signal-to-noise ratio and quasiinstantaneous measurements of optical spectra. It requires the generation of two mutually coherent optical frequency combs, and electro-optical modulation of a monochromatic carrier can be used for this purpose. By tuning the applied modulation frequency, it is possible to control the spacing between the lines of the electrooptical frequency combs (EOFCs), and by changing the input carrier frequency, it is possible to control the EOFCs absolute frequencies. On-chip EOFC generators are highly desirable to develop low-cost and low-weight dual-comb systems. In this context, silicon photonics is a promising technology, as it benefits from CMOS compatible fabrication process. In this work, a demonstration of dual-comb generation is performed, using two silicon Mach-Zehnder modulators. The tunablity of the obtained 5 main beat notes was studied for an input wavelength ranging from 1530 nm to 1570 nm, and for a driving modulation frequency between 1 GHz and 12 GHz.