VECSEL Optimization Using Microscopic Many-Body Physics

Vertical external cavity surface-emitting lasers (VECSELs) are designed and analyzed using an approach based on fully microscopically computed material properties like gain and carrier recombination rates. Very good agreement between theoretical predictions and measured characteristics of the realized devices is demonstrated. The high accuracy of the theoretical models allows one to determine even small deviations between the nominal designs and actual realizations. The models are used to find optimization strategies. It is shown how the external efficiency can be strongly improved using surface coatings that reduce the pump reflection while retaining the gain-enhancing cavity effects at the lasing wavelength. It is shown how incomplete pump absorption can be detrimental to the device performance and how this problem can be reduced using optimized distributed Bragg reflectors and metallization layers. A combination of improved metallization and use of such a coating more than doubles the external efficiency and maximum power for a realized VECSEL operating at 1010 nm and the theory indicates that further significant improvements are possible.