Photonic Integrated Circuits For Surface Enhanced Raman spectroscopy: Atomic Layer Deposition Assisted Enrichment and Integration of Plasmonic Nanostructures and Nanophotonic Waveguides

Raman spectroscopy (RS) is a powerful technique to identify the composition of a material by probing the mechanical vibration of molecules using a laser beam and detecting the shift in the optical frequency induced by the vibrating molecules. It has many applications ranging from the detection of counterfeiting to monitoring chemical processes and probing living cells. The key challenge with RS is twofold: firstly, the Raman signal is extremely weak and secondly, the equipment is bulky and expensive. The weak Raman signal can be boosted by orders of magnitude when the vibrating molecules are in close vicinity of metal nanostructures, through a technique called surface enhanced Raman spectroscopy. For miniaturization, different functionalities need to be integrated on a single chip. Therefore, to make the technique viable, a low-cost approach is required to produce high quality photonic integrated circuits (PICs) with metal nanostructures with nanometer accuracy in a very reproducible manner. In this project, we will explore an entirely new and promising avenue to turn RS into a technique that can be incorporated in low-cost, compact devices. We will use atomic layer deposition (ALD) to first enrich silicon nitride based PICs and then create metal nanostructures on the PICs connected to optical fibers. As a proof-of-concept we will use this device to monitor the chemical processes in an ALD-reactor itself, thereby taking full advantage of the compactness of the device.