Electronically Tunable-Laser Light Sources for near Infrared Spectroscopy

This review paper focuses primarily on the recent progress in the development of electronically-tuned solid-state lasers and their application in near infrared (NIR) absorption and Raman spectroscopies. It also discusses the expansion of the tunable range and the generation of ultrashort pulses. Electronic control of laser wavelengths using an acousto-optical tunable filter (AOTF) was developed to provide rapid, accurate and random access to numerous wavelengths offering a programmable monochromatic energy under computer control. In contrast to tunable diode lasers that are for specific gaseous spectroscopic analysis, this type of stable, widely-tunable lasers is suited for the measurement of both liquid and solid samples, including biological materials, materials that have broad and overlapping features over a wide spectral range. In addition, some preliminary applications are presented, together with the present status of other tunable light sources applicable for NIR spectroscopy.