Rapid Shifted Excitation Raman Difference Spectroscopy with a Distributed Feedback Diode Laser Emitting at 785 nm

ArticleinApplied Physics B 85(4):509-512 · November 2006with57 Reads
Impact Factor: 1.86 · DOI: 10.1007/s00340-006-2459-8

    Abstract

    A distributed feedback (DFB) laser diode emitting at 785nm was tested and applied as a light source for shifted excitation Raman difference spectroscopy (SERDS). Due to the physical properties of the laser diode, it was possible to shift the emission wavelength by 8cm-1 (0.5nm) required for our SERDS measurements by simply changing the injection current. The internal grating ensured single mode operation at both wavelength with the frequency stability of ±0.06cm-1 (0.004nm) required for high resolution Raman spectroscopic applications. The shifted spectra were used for calculating enhanced Raman spectra being obscured by a strong scattering background. A 16dB (≈38 fold) improvement of the signal-to-background noise S̄/σB was demonstrated using blackboard chalk as a sample. The tunable DFB laser is a versatile excitation source for SERDS, which could be used in any dispersive Raman system to subtract fluorescence contributions and scattering background.