COLOR CENTER LASERS FOR INFRARED SPECTROSCOPY

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