Pushing the limits of CMOS optical parametric amplifiers with USRN:Si<sub>7</sub>N<sub>3</sub> above the two-photon absorption edge.

Ooi, K J A; Ng, D K T; Wang, T; Chee, A K L; Ng, S K; Wang, Q; Ang, L K; Agarwal, A M et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

CMOS platforms operating at the telecommunications wavelength either reside within the highly dissipative two-photon regime in silicon-based optical devices, or possess small nonlinearities. Bandgap engineering of non-stoichiometric silicon nitride using state-of-the-art fabrication techniques has led to our development of USRN (ultra-silicon-rich nitride) in the form of Si<sub>7</sub>N<sub>3</sub>, that possesses a high Kerr nonlinearity (2.8 × 10<sup>-13</sup> cm<sup>2</sup> W<sup>-1</sup>), an order of magnitude larger than that in stoichiometric silicon nitride. Here we experimentally demonstrate high-gain optical parametric amplification using USRN, which is compositionally tailored such that the 1,550 nm wavelength resides above the two-photon absorption edge, while still possessing large nonlinearities. Optical parametric gain of 42.5 dB, as well as cascaded four-wave mixing with gain down to the third idler is observed and attributed to the high photon efficiency achieved through operating above the two-photon absorption edge, representing one of the largest optical parametric gains to date on a CMOS platform.