Distributed Bragg reflector ring oscillators: A large aperture source of high single-mode optical power

Distributed-Bragg-reflector (DBR) ring oscillators are the first monolithic semiconductor lasers containing broad-area active regions which operate in a single mode to several times their threshold current. Orthogonally oriented diffraction gratings surrounding an unpatterned active region select a single spatial and temporal mode of oscillation. The authors present both analytic and experimental verification of single mode operation for active dimensions up to 368 μm×1000 μm. Threshold current densities under 200 A/cm² and total differential efficiencies greater than 60% have been measured. DBR ring oscillators have demonstrated over 1 W of single frequency output power, 460 mW of spatially coherent, single frequency output power, and nearly circular diffraction limited output to 4xI_th. The performance potential of these devices is enormous, considering that the output apertures are nearly two orders of magnitude wider than conventional single-mode sources which generate up to 0.2 W of coherent output