Pump Diode Characterization for an Unstable Diode-Pumped Alkali Laser Resonator.

摘要

Measurements of wavelength tunability, spectral linewidth, minimum spot size, and M2 were made for a rubidium diode-pumped alkali laser (DPAL) containing a volume Bragg grating (VBG) for resonator characterization. The output wavelength of the pump diode was measured as a function of volume Bragg grating temperature. A linear relationship was observed that corresponded to an output wavelength range of 780.08 nm 0.01 nm to 780.49 nm 0.01 nm with a tuning rate of 6.1 pm/ C for a diode chassis temperature of 37 C. Rubidium D1 fuorescence spectra were recorded as the diode wavelength was scanned across its full range in 3 pm steps. The integrated intensities of the D1 fluorescence peaks were used to generate a t to a Lorentzian lineshape with line center at 780.23 nm and a FWHM of 0.12 nm. A knife-edge experiment measured the power pro les of the pump diode beam along a 4.5 cm beam path. The pump diode M2 was determined by a nonlinear model t to be 132, resulting in a minimum spot size of 0.41 mm. These results enable the pump diode to be matched with a alkali gain media for the validation of unstable DPAL resonator designs.