Customized diode lasers for spectroscopic applications

Friday, February 7, 2014

12:00 pm | Schiciano Auditorium - Side A

Presenter

Dr. Bernd Sumpf , Senior Scientist

Diode lasers are widely used compact and robust light sources for different purposes. Beside high-power applications in material processing (welding, soldering, etc.) and as pump sources for other lasers, they are also used in medical and sensor applications. The latter includes the direct application of these devices as well as the use of diode lasers as pump sources for other more complex laser systems.

Different semiconductor materials allow manufacturing laser devices from the ultraviolet spectral range up to the mid-infrared. The use of ternary mixtures allows adjusting the wavelength of the devices to requested values. Gaps in spectral coverage can be filled by applying non-linear processes, like second harmonic generation (SHG), sum frequency generation (SFG) or difference frequency generation (DFG).

In this paper, a brief overview of customized diode lasers for spectroscopic applications in the VIS- and NIR-range will be given. This includes the design and manufacturing of such devices, their typical electro-optical, spectral and beam properties.

Special focus will be given to wavelength stabilized monolithic DBR- and DFB-diode lasers and SHG light sources suitable for Raman spectroscopy. Moreover, selected diode laser based light sources will be presented suitable for shifted excitation Raman difference spectroscopy (SERDS). Devices for the wavelengths 488 nm, 671 nm, and 785 nm are presented. The two emission wavelengths for SERDS are selected with a spectral distance of about 10 cm-1 Output powers up to 50 mW for devices at 488 nm and up to 200 mW for the red emitting lasers are achieved at electrical power consumptions below 1 W. Electro-optical and spectral properties will be given. Raman experiments with selected samples demonstrate the suitability of such compact light sources for SERDS even for portable applications.

Dr. Bernd Sumpf is a Senior Scientist, Group Leader of Laser Measurement and Laser Sensors at Ferdinand-Braun-Institut Optoelectronics Department Berlin, Germany .  He is currently a lecturer at the Technische Universität Berlin, Department of Physics, Diode Laser Spectroscopy.  Research topics of Dr. Sumpf are 1) high-brightness, high-power diode lasers 2) diode lasers for sensor applications, especially rotational-vibrational spectroscopy 3) non-linear frequency conversion of diode lasers.  The current projects that Dr. Sumpf is working on is light sources for Raman spectroscopy; development of dual wavelength diode lasers for Shifted excitation Raman difference spectroscopy; basics for a new clinical diagnostics using optical methods for skin analysis; and usability of environmentally sound and reliable techniques in Precision Agriculture.