Gain coupling VECSELs

Vertical external cavity surface emitting lasers (VECSELs) provide a laser design platform in order to explore a variety of systems, and their flexibility eases this exploration. Moreover, their high-brightness operation makes them attractive for many applications. In considering the methods of coupling VECSELs as well as their potential uses, we begin by reporting on the development of a gain coupled VECSEL for use in optical switching. In particular, two VECSEL cavities share a common gain region; the competition for a common set of carriers dictate how these cavities interact. The easiest manifestation to realize gain coupling is to utilize a linear cavity as well as a v-cavity, built around a single half-vertical cavity surface-emitting laser (VCSEL) chip. The cavity gain/loss of each cavity can be controlled independently through use of birefringent filters, allowing us to explore the design space, which can be divided up into coarse behavior, easy to analyze through comparing the two uncoupled lasers, and a fine behavior, where one cavity will affect the other and each cavity can lase simultaneously, sometimes at dramatically different wavelengths. These two regions may be explained with simple rate equations, and it will be shown that if prepared properly, spontaneous emission plays a large role in balancing the two laser cavities within the fine regime, while may be completely neglected in the coarse regime.