Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers.

ABSTRACT

The longitudinal multi-mode emission in a vertical-external-cavity surface-emitting laser is investigated using both single shot streak camera measurements and interferometric measurement techniques. For this, the laser is operated in the single- and two-color emission regime using both an etalon and a free-running configuration without etalon, respectively. The laser emission is analyzed with respect to pump power and output coupling losses for a long and for a short resonator. We observe a steep increase of emission bandwidth close to the laser threshold and monitor the transition between longitudinal single- and multi-mode operation. Additionally, the results indicate that a stable two-color operation is related to a sufficiently high number of oscillating longitudinal modes within each color.