Design and characterization of MECSELs for widely tunable (>25 THz) continuous wave operation

Membrane external-cavity surface-emitting lasers (MECSELs) are vertically emitting semiconductor lasers that combine all the benefits of VECSELs (vertical-external-cavity surface-emitting lasers) with the new degree of freedom in creating gain structures without monolithically integrated distributed Bragg reflectors (DBRs). The absence of the DBR and the substrate, and the use of a very thin gain membrane (typically some hundreds of nanometers), which can be sandwiched between two transparent heat spreaders, represents the best solution for heat removal. The membrane configuration also allows the option of double side pumping, which in turn makes it possible to utilize an extensive amount of quantum well (QW) groups as well as multiple kinds of QWs in a periodic laser gain structure. Here we report on design strategy and results of different kinds of approaches on broadband, relatively high power MECSEL gain structures. Especially efficient pump absorption, sufficient gain on several different wavelengths and carrier mobility during laser operation, are discussed. We also present the characteristics of the laser systems created. Results show ∼83 nm (∼25 THz) tuning range with more than 100 mW of power at all wavelengths at room temperature operation. Strategies for further development are discussed as well.