Compact turnkey system for multi-contact diode lasers for portable spectroscopic applications

Abstract

Diode laser-based light sources allow the implementation of features to meet specific application requirements. Besides output power and specific wavelength, this can also include spectral tunability, an alternating operation between two different wavelengths, or a well-defined parallel operation at two wavelengths. Potential applications involve spectroscopic systems and applications, e.g., in Raman spectroscopy, especially shifted excitation Raman difference spectroscopy (SERDS) or sequentially shifted Raman spectroscopy, absorption spectroscopy, or the generation of THz radiation. To meet these demands, diode laser based light sources often use a multi-contact layout. Their operation may require multiple individually adjustable current sources, adjustable galvanically isolated current sources, regulated temperature stabilization and heat removal. Moreover, an interface, e.g., a fiber coupling unit is required to transfer the laser light to the experiment. In this paper, a compact turnkey system is reported meeting these requirements with up to 10 current sources, 2 galvanically isolated current sources, integrated temperature control and an interface for laser light transfer is presented. The system has dimensions of 177 mm × 124 mm × 48 mm and is controlled via a standard USB interface. It additionally provides a synchronization signal for implementation into multi-instrument setups. The current sources are based on implemented dual continuous wave p-type laser diode drivers. Ten current sources with 750 mA enabling switching frequencies up to 1000 Hz and four galvanically isolated current sources with 2 W are available. For temperature control, a TEC controller is used. An effective cooling system allows 10 W of thermal load to be removed. The integration of this turnkey-system into a portable shifted excitation Raman difference spectroscopy sensor system is briefly presented as an example application.