Diode laser based light sources for shifted excitation resonance Raman difference spectroscopy in the spectral range between 450 nm and 532 nm
Although resonance Raman spectroscopy enhances Raman signals significantly, they can be obscured by background light. When exciting the target with two neighboring wavelengths only Raman lines follow that change in the excitation wavelength and can be separated from the background. The required monolithic, narrow linewidth, dual wavelength diode lasers in the blue/green spectral range are not available. Potential laser sources are therefore based on external cavity GaN lasers and devices using the second harmonic generation of GaAs laser emission. Concepts and features of these light sources in the spectral range from 450 nm to 532 nm will be presented.
Bernd Sumpf received the diploma in Physics in 1981 and the Ph.D. degree in 1987 from the Humboldt-Universität Berlin for his work on lead salt diode lasers for spectroscopic applications. From 1993 till 1997 he worked at the Technische Universität Berlin on high-resolution spectroscopy and difference-frequency generation. In 1997 he received the postdoctoral lecture qualification. Since 2000 he works at the Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik, Berlin, Germany on high power and high brightness diode lasers and diode lasers and their application for Raman spectroscopy in life sciences. He is author of more than 330 publications and inventor and co-inventor of 5 patents in the field of diode lasers and laser spectroscopy.