Competitive Advantages:
Can detect a large number of chemical species using a single laser source, Trace gas recorded under atmospheric conditions with a limit of detection below 1 part-per-million, High laser power and narrow linewidth obtained with low cost input power.
A method for enhancement of spontaneous Raman scattering (SRS) from gases comprising a multimode blue laser diode which receives feedback from a near concentric bidirectional multipass cavity in such a way as to generate a circulating power of order 100 W for a sample volume of 10 mm3. The feedback, provided via a volume Bragg grating, reduces the laser bandwidth to 4 cm-1. Spectra of spontaneous Raman scattering from ambient atmospheric air, detected collinearly with the pump, were recorded with a limit of detection below 1 part-per-million. The proposed device, developed by our researchers, employs a multimode blue laser diode which receives feedback from a concentric bidirectional multi-pass cavity. The laser bandwidth is reduced to 4 cm-1 as a result of the feedback provided via a volume Bragg grating. As a result, the spectra of spontaneous Raman scattering from ambient atmospheric air is recorded within a limit of detection below 1 parts-per-million. The effectiveness of the device is demonstrated through detection of acetone, methane and isotopic carbon dioxide in breath. This technology can be used in medical diagnostics, hazardous gas monitoring, environmental detection or even in simple home gas detection/monitoring.
