40 years of nonlinear optics in photonic crystals

Abstract:

Nearly 40 years ago, E. Yablonovitch suggested that forbidden bands, induced in the optical spectrum in dielectrics with a suitable periodic structure could modify light-matter interactions, potentially leading to improved light sources [1]. That same year, S. John highlighted that defects within such structures would strongly localize light, thereby enhancing their optical nonlinear response [2]. Meanwhile, Chen and Mills noted that nonlinearity could significantly alter the transmission properties of periodic optical lattices[3]. Since then, advancements in fabrication techniques and a deeper understanding of nonlinear periodic optical structures have progressed significantly. We will present examples demonstrating the remarkable and often unexpected developments arising from these pioneering concepts. The tight localization of light within photonic crystal resonators results in a substantial nonlinear response, facilitating the demonstration of optical memories, optical switches, and nanoscale lasers, all of which have implications for optical interconnects and high-performance computing. A noteworthy characteristic of photonic crystal resonators is that the energy distribution of their eigenmodes is highly non-uniform and, more importantly, can be engineered. For instance, we have demonstrated an ultra-compact resonator featuring high-Q modes with a Hermite-Gauss distribution [4], and here we will discuss some of the associated implications. First, such modes within a laser cavity could enable a novel form of mode-locking [5], which we have recently observed experimentally. Additionally, by accurately controlling the frequency spacing, the parametric gain due to four-wave mixing is enhanced by a factor proportional to (Q^2/V), allowing a micrometer-scaled Optical Parametric Oscillator (OPO) to operate with a power threshold as low as 50 μW [6]. Given that OPOs are crucial in quantum optics as sources of entangled photon pairs and squeezed light, we have shown that energy-time entangled pairs are generated in our nanoscale OPO at high rates (over 20 MHz) and with significant visibility (over 96%), which may be relevant for large-scale integrated quantum photonic circuits.[7] The next challenge lies in the heterogeneous integration of such structures within advanced photonic integrated circuits, unlocking new opportunities in the field of quantum technologies.

[1] E. Yablonovitch, "Inhibited Spontaneous Emission in Solid-State Physics and Electronics", Phys. Rev. Lett. 58, 2059 (1987)

[2] S. John, "Strong localization of photons in certain disordered dielectric superlattices", Phys. Rev. Lett. 58, 2486 (1987)

[3] Chen and Mills, "Gap solitons and the nonlinear optical response of superlattices", Phys. Rev. Lett. 58, 160 (1987)

[4] S. Combrié, et al., “Comb of high‐Q Resonances in a Compact Photonic Cavity”. Laser & Photonics Reviews. 11, 1700099 (2017)

[5] Y. Sun et al., "Mode Locking of the Hermite-Gaussian Modes of a Nanolaser", Phys. Rev. Lett. 123, 233901 (2019)

[6] G. Marty, et al. , “Photonic crystal optical parametric oscillator”. Nature Photonics 15, 53 (2021)

[7] A. Chopin et al. "Ultra-efficient generation of time-energy entangled photon pairs in a InGaP Photonic Crystal Cavity.", Commun Phys 6, 77 (2023).