Annealing-free Si3N4 frequency combs for monolithic integration with Si photonics

Houssein El Dirani (1) , Ayman Kamel (2) , Marco Casale (1) , Sébastien Kerdiles , Christelle Monat (3) , Xavier Letartre (3) , Minhao Pu (4) , Leif Katsuo Oxenløwe (4) , Kresten Yvind (2) , Corrado Sciancalepore (3)

1 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
2 DTU - Danmarks Tekniske Universitet = Technical University of Denmark
3 INL - Photonique - INL - Nanophotonique
4 DTU Fotonik

Silicon-nitride-on-insulator (SiNOI) is an attractive platform for optical frequency comb generation in the telecommunication band because of the low two-photon absorption and free carrier induced nonlinear loss when compared with crystalline silicon. However, the high-temperature annealing that has been used so far for demonstrating Si3N4-based frequency combs made the co-integration with silicon-based optoelectronics elusive, thus reducing dramatically its effective complementary metal oxide semiconductor (CMOS) compatibility. We report here on the fabrication and testing of annealing-free SiNOI nonlinear photonic circuits. In particular, we have developed a process to fabricate low-loss, annealing-free, and crack-free Si3N4 740-nm-thick films for Kerr-based nonlinear photonics featuring a full process compatibility with front-end silicon photonics. Experimental evidence shows that micro-resonators using such annealing-free silicon nitride films are capable of generating a frequency comb spanning 1300-2100 nm via optical parametrical oscillation based on four-wave mixing. This work constitutes a decisive step toward time-stable power-efficient Kerr-based broadband sources featuring full process compatibility with Si photonic integrated circuits (Si-PICs) on CMOS-.lines.

Domaines: Optique / photonique

Houssein El Dirani, Ayman Kamel, Marco Casale, Sébastien Kerdiles, Christelle Monat, et al.. Annealing-free Si3N4 frequency combs for monolithic integration with Si photonics. Applied Physics Letters, 2018, 113 (8), ⟨10.1063/1.5038795⟩. ⟨hal-01917898⟩