COLOR CENTER LASERS FOR INFRARED SPECTROSCOPY

[摘要] Two color center laser spectrometers have been developed using an F(,A)(II) and F(,B)(II) color center laser system for the 2.2-3.3 (mu)m region, and a powerful single mode F(,2)(;;+) color center ring laser for the 0.82-1.05 (mu)m region. Both lasers are interfaced to a minicomputer to provide long range scanning, high resolution data acquisition, and automatic calibration. Single mode scans with a resolution of 0.01cm(;;-1) are possible over the entire tuning range of the lasers; continuous single mode scans with a resolution of 10(;;-4)cm(;;-1) are possible over 1 cm(;;-1) ranges. An extensive set of software algorithms and a stable hardware interface between the laser and computer are necessary to reliably control and calibrate the lasers. Evaluation of the F(,A)(II) and F(,B)(II) laser spectrometer led to the development of a method to improve the sensitivity of absorption spectroscopy. The method, described as magnetic rotation spectroscopy, uses the Faraday effect to modulate the polarization of a beam travelling through a paramagnetic specie. This technique has been tested on NO, and has led to the first observations of the free radical OH(;;-) in the 2.7 (mu)m region, and the complete (;;2)P(,1/2) (<---) (;;2)P(,3/2) transition in B(,r). An F(,2)(;;+) color center has been built in a ring configuration to obtain maximum single mode output power. Design criteria for the laser resonator, the ;;optical diode;; which forces unidirectional operation of the laser, and the tuning system have been developed to prolong the lifetime of the F(,2)(;;+) crystal, and to insure stable and unidirectional single mode operation.

[发布机构] Rice University