RECONFIGURABLE MEMS WAVEGUIDE BASED ON PHOTONIC CRYSTAL MEMBRANE

摘要

We present our design and fabrication of a semiconductor based photonic bandgap (PBG) nano-membrane device with MEMS features. This device could be used as a basic building block for a reconfigurable optoelectronic integrated circuit that can be reprogrammed for different functionalities. We combine a PBG platform with a MEMS feature to build such a reconfigurable device. The device has a top PBG membrane layer structure composed of hexagon holes in a triangular lattice. Below that, a separate suspended bridge layer can insert a line of posts into the photonic crystal holes to create a defect line. This MEMS feature can generate/cancel a section of the waveguide in the PBG platform, or it can change the dispersion of the waveguide. Therefore, the same structure can be used as different types of devices such as switches, modulators, time delay lines, etc. This device is fabricated on GaAs/Al_(x1)GaAs/Al_(X2)GaAs/GaAs-substrate epi-layers grown by MBE. We have developed the fabrication technique for such a device using e-beam lithography, inductively coupled plasma (ICP) reactive ion etching, and multiple steps of regular photolithography and selective wet chemical etching. The fabricated PEG membranes are 60 nm to 300 nm thick, with a thin wall between the holes of ～120 nm. A line of mushroom shaped MEMS posts are inserted into the ～1 μm PEG holes. We are fine tuning each of these processing steps toward the fabrication of a workable device.