Spectroscopy of diatomic molecules using external cavity diode laser in the visible range

摘要

Abstract: A compact and economic system is proposed for diode laser single-longitudinal-mode selection, oscillation linewidth narrowing and frequency tuning by means of feedback from a diffraction grating in Littrow configuration. For single- mode frequency tuning, an electromagnetic driver is applied which provides a few hundreds of microns change of the diode laser external cavity length. Continuous frequency scans over 50GHz are realized. Improved shape and coincidence with the diode laser axis of he output laser beam is achieved by means of 1 mm aperture in the diffraction grating. Laser wavelength measurement is performed using high diffraction orders of a diffraction grating with small period. The performance of the system is demonstrated resolving I$-2$/ and Na$-2$/ ro-vibrational absorption spectra in the spectral region around 670nm. The identified I$-2$/ absorption spectrum can be applied for diode laser stabilization at many points of their tuning regions with known absolute wavelengths. !11