Diode-pumped broadband vertical-external-cavity surface-emitting semiconductor laser applied to high-sensitivity intracavity absorption spectroscopy

A diode-pumped broadband multiple-quantum-well vertical-external-cavity sur face-emitting semiconductor laser has been developed for high-sensitivity i ntracavity laser-absorption spectroscopy. The semiconductor structure desig n has been optimized so as to provide maximum laser-emission bandwidth and wavelength tunability. The laser has a 100-mW threshold of continuous room- temperature operation, and it can be tuned within 25 nm around its design w avelength (980 nm). A detection limit lower than 10(-10) per centimeter of absorption path has been achieved, given similar to 3 x 10(-11) cm(-1) Hz(- 1/2). Its spectre-temporal dynamics has been studied in the time range from a few microseconds to similar to 1 s. No evidence of nonlinear mode intera ctions, which in many cases limit the sensitivity, has been observed. We ha ve also shown that with a cavity length reduced to 2.5 cm, the laser is ver y attractive as a tunable single-frequency source owing to its stable opera tion in a single TEM00 mode at a pump power of up to 1 W. (C) 2000 Optical Society of America [S0740-3224(00)01107-3].