Nonlinear Dynamics in Integrated 2D Photonic Crystal Optomechanical Cavities

We present our heterogeneous integrated resonator based on a photonic crystals molecule optomechanically coupled to a suspended InP nanomembrane. Optomechanical experimental observations of its nonlinear features induced by a Kerr-type optical bistability will be discussed.

Multimode optomechanics has been widely explored in the last years for its promising applications in nonlinear signal processing. The use of several optical modes coupled to a common mechanical mode can lead to interesting properties such as nonreciprocal states[1] or spontaneous symmetry breaking[2] and can be studied both in the quantum or classical picture. The use of 2D Photonic Crystal (PhC) for optomechanical applications allows the implementation of a large variety of structures from single optical cavity [3] to photonic molecules. Our platform consists of an InP nanomembrane suspended over an integrated silicon waveguide (Figure). Our 2D crystal includes two L3 defect cavities that are both coupled to the mechanical drum modes of the membrane. By playing on the relative positions of the defect-cavities, both their direct evanescent coupling and their indirect coupling through the waveguide can be controlled. Because of a asymmetric geometry of our structure, the modes have different optical quality factors. Therefore, one can be driven in a Kerr-type bistability regime at sufficiently high optical power while the other stays unchanged and can be used for a passive read-out of the mechanical properties. We will discuss the nonlinear properties of this system including the generation of mechanical sidebands in a large range of optical modulation frequencies as well as randomly modulated mechanical resonance frequency in the optical bistability region. These features paves the way towards noise aided nonlinear dynamics with multiples coupled optomechanical resonators such as stochastic resonance or synchronized patterns.

[1] Physical Review Applied 7,064014 (2017)

[2] Physical Review A 95,053822 (2017)

[3] Scientific Reports volume 5, 16526 (2015)

Figure - left : schematic of the integrated platform; Right : SEM image of the InP photonic molecule.

guilhem.madiot@c2n.upsaclay.fr