Silicon photonics phase and intensity modulators for flat frequency comb generation
Lucas Deniel, Erwan Weckenmann, Diego Pérez‐Galacho, Christian Lafforgue, S. Monfray, Carlos Alonso‐Ramos, Laurent Bramerie, F. Bœuf, Laurent Viven, Delphine Marris‐Morini
Abstract
Flat electro-optical frequency combs play an important role in a wide range of applications, such as metrology, spectroscopy, or microwave photonics. As a key technology for the integration of optical circuits, silicon photonics could benefit from on-chip, tunable, flat frequency comb generators. In this article, two different architectures based on silicon modulators are studied for this purpose. They rely on a time to frequency conversion principle to shape the comb envelope. Using a numerical model of the silicon traveling-wave phase modulators, their driving schemes are optimized before their performances are simulated and compared. A total of nine lines could be obtained within a 2 dB flatness, with a line-spacing ranging from 0.1 to 7 GHz. Since this tunability is a major asset of electro-optical frequency combs, the effect of segmenting the phase modulators is finally investigated, showing that the flat lines spacing could be extended up to 39 GHz by this method.