Bending behavior of a flexible single crystal nanomembrane photonic crystal cavity
|
In this paper, we present experimental and theoretical studies on the bending induced resonance shift of a photonic crystal cavity. The photonic crystal devices are fabricated on a 2cm x 2cm large-area single crystal SiNM which is transferred defect-freely onto a Kapton substrate with an SU-8 bottom cladding. Photonic crystal tapers are implemented at the strip-photonic crystal waveguide interfaces, which lowers the coupling loss and enables operation closer to the band edge. Subwavelength grating (SWG) couplers are employed at the input and output of the device in order to enable device characterization. The device is mounted on the two jaws of a caliper and it can be buckled up and down through sliding one of the jaws. The bending radius at the top of the curvature can be estimated with the length of the specimen and the distance between the two jaws. A minimum bending radius of 5 mm is achieved. Finite element method (FEM) is used to simulate the deformation and the strain of the nanomembrane. The results are used as the input of finite difference time-domain (FDTD) simulation. The analysis shows that the strain sensitivities are 0.673 pm/με, 0.656 pm/με, 0.588 pm/με, and 0.591 pm/με, for longitudinal face-out, longitudinal face-in, transverse face-out, and transverse face-in bending, respectively. |
