Fiber-optic Raman probe based on single-crystal sapphire fiber

We demonstrate a fiber-optic Raman probe based on single-crystal sapphire fibers to overcome the large background signal of Raman probes based on standard glass fibers. Using 514.5 nm and 785 nm excitation lasers, Raman spectroscopy was performed on samples of calcite, aqueous sodium carbonate solution, and silicon wafer using a single crystal sapphire fiber and a silica fiber of similar lengths and numerical apertures. The single-crystal sapphire fiber exhibits narrow Raman peaks and low background signal, allowing for the detection of weaker Raman signals or Raman signals located in the lower wavenumber region, while the traditional silica fiber has a strong broadband Raman spectrum of its own.