Exploring Silicon Photonics to Sense Two-Dimensional Membrane Mechanics

Abstract

Silicon photonics have received more attention in recent years due to further development in CMOS manufacturing methods. The development allows silicon photonics to be smaller than ever before. This leads to smaller silicon photonic devices that can transceive light, which is typically done at a wavelength of 1550nm for silicon photonics. A silicon photonic device that benefits from this wavelength is the silicon waveguide, which can transceive light by being coupled to other waveguides. When the second guide is later coupled back with the main waveguide, a resonance can form between the guides. This can turn the silicon waveguide in to a sensor that relies on interference from the recoupled signal. The design used for this study has the waveguides in a relatively deep trench, which means that a membrane can be suspended above the waveguides. In theory the membrane should reflect some of the light that escapes from the waveguide back. In this work membranes made from graphene and molybdenum disulfide are suspended over a silicon waveguide in hopes to detect the motion of the membrane. A proof of concept by experimenting with membranes integrated on silicon photonics can give way for a new type of sensor, which is both microscopic and has a high signal-to-noise ratio. The experiments are conducted by propagating light through the waveguide, the light should then interact with the suspended membrane on top. The first indication that the concept was possible was when a transmission graph that swept the light’s wavelength around 1550nm changed after introducing a suspended membrane over the waveguide. The change showed that waveguides react to membranes over them without eliminating the transmission altogether. This is a great step when it comes to a proof for the concept. However, it is still needed to take a frequency measurement before the concept has been fully proofed.