Waveguide-enhanced Raman spectroscopy using visible laser excitation

Abstract

Waveguide-enhanced Raman spectroscopy (WERS) using nanophotonic waveguides has been used to demonstrate the detection of vapor-phase chemicals and liquid-phase biomolecules in water. The technique benefits from the fabrication processes and tolerances of CMOS foundries, but successful foundry-based WERS photonic integrated circuits (PICs) have only been demonstrated using excitation wavelengths of 1064 nm and 785 nm. Foundrybased PICS are beginning to operate with low loss at visible wavelengths, and WERS is uniquely poised to take advantage of this capability. Raman scattering cross-sections scale as λ −4 , so a visible WERS platform could enable increased sensitivity, decreased exposure times, and/or decreased laser powers. However, increased fluorescence, increased waveguide loss, and decreased feature sizes make WERS in the visible challenging. Here, we demonstrate WERS using 300-mm foundry-based fabrication (AIM Photonics) with 633 nm and 785 nm laser excitation. We also show the successful operation and integration of other required components for a compact WERS system operating in the visible, including edge-couplers and lattice filters.