Fundamental study of a simple diode laser power build-up cavity for multi-gas sensor

Summary form only given. Air pollution is a very serious problem nowadays and many kinds of gas sensing techniques have been studied. Among these techniques, Raman spectroscopy has a big advantage to apply to multi-gas sensor for medical application, because the specific wavelength shift by one laser wavelength can be identified. However, it requires a high power laser, such as a Ar ion laser or Kr ion laser, to generate sufficient Raman signals. To miniaturize a laser gas sensor, a simple diode-pumped power build-up cavity (PBC) was reported by D.A. King. The PBC consists of an anti-reflection (AR)-coated low power laser diode, gradient index (GRIN) lens, and PBC, which is a high finesse external cavity; it can generate 100 W intracavity power. This interesting coupled resonator as a Raman light source has been studied in detail. But the physical analysis of it hasn´t done enough yet. We report the characteristics as a coupled resonator.