Photonic crystals (PCs) are gaining much interest because of their potential for controlling light. For applications in optical devices, dynamic tuning of the PC characteristics is important. The characteristics of 2D PCs are defined by the refractive index of their materials and air hole geometries (i.e. lattice constants and air hole shapes). Methods for tuning PC device have been proposed, which changes the refractive index of the slab with electro-optic effect [1]. Mechanical tuning of PCs by inserting silicon rods into PC air holes is difficult, because we should precisely align the rods to the holes. In previous studies, AFM probes were used for tuning the property of PC devices [2]-[3]. These methods need an AFM apparatus to align the tip of the probe to the target hole. In this study, we propose a mechanically tunable PC device with an electrostatic actuator fabricated by MEMS technique. A schematic drawing of our device is shown in Fig. 1. The device consists of two parts: a flexible PC slab waveguide; and double-layered rods which consist of silicon (upper layer) and silicon dioxide (lower layer). The rods are fixed to the wafer, while the slab is released from the wafer. In the initial state (Fig. 1 (b)), the holes are mostly filled with the silicon part of the rods. When a voltage is applied between the slab and the wafer, the slab is deflected by electrostatic force (Fig. 1 (c)). Therefore, the holes are mostly filled with the silicon dioxide part of the rods. The deflection (i.e. the insertion depth of the rods) depends on the applied voltage. Since the rods are self-aligned to the holes, our device does not need other alignment apparatus, like an AFM.
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