Abstract

What does it take to integrate a complete Raman spectroscopy system on a photonic chip of less than a square cm? This question will be addressed in this presentation, whereby both the key assets of a chip-based approach and the key challenges involved will be covered.
A Raman spectroscopy system consists of a pump laser, an optical pathway to the analyte, an interaction region with the analyte, another optical pathway to a spectrometer, the spectrometer itself and a detector array. Implementing all these elements on a photonic chip is feasible with today’s photonic integration platforms such as silicon photonics, but doing so in a way that the performance is comparable to that of a system based on free space optics is highly challenging.
In this presentation I will report on an exploration of variety of options in this chip-based implementation. At the heart of the system is the actual sensor where pump light interacts with the analyte. In the systems being discussed we use optical waveguides both to couple pump light to the analyte (which acts like a cladding to the waveguide) and to collect the Stokes scattered light. A variety of modalities will be discussed: dielectric strip and slotted waveguides, nanoplasmonic antennas on dielectric waveguides and plasmonic metal-slot waveguides. The waveguides being used are single mode waveguides because these allow to inject diffraction-limited light into the spectrometer, thereby enabling the smallest possible footprint for such a spectrometer for a given spectral resolution.
The Raman-on-a-chip systems being reported will be benchmarked against free space Raman spectroscopy as well as against Raman spectroscopy based on SERS-substrates.

Related Research Topics

• Nanoplasmonic approach for Raman spectroscopy on siliconnitride waveguides