A high-precision optical position sensor using integrated photonics

What is it about?

Over the last decades, the interest in the field of silicon photonics has grown significantly. One main motivation is to decrease the footprint of existing optical devices, such as sensors or communication systems, by integrating them on a silicon-on-insulator platform. This technology offers several advantages such as transparency of the material at the typical telecommunication wavelength of 1550 nanometer, as well as compatibility with existing integrated circuit technology. Here, we developed an integrated optical position sensor based on the excitation of a silicon nano-cylinder with a tailored light field, leading to position-dependent coupling to silicon waveguides. It is capable of resolving displacements as small as 7.2 nanometer, which is about 35 times better than the classical resolution limit achievable in visible light microscopy.

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Photo by FLY:D on Unsplash

Photo by FLY:D on Unsplash

Why is it important?

We expect the developed sensor to be of large interest in semiconductor manufacturing technology. In modern lithography systems, the precise, repeatable positioning of the photomask with respect to the chip is a crucial requirement. The sensor presented in this work is especially suitable for such an application due to its all-optical working principle and the fact that the sensor output is directly related to both direction and magnitude of a change in position.