Power coupling between gain-guided index-antiguided planar waveguides.

Power coupling between two gain-guided index-antiguided (GGIAG) planar waveguides is numerically investigated. The strength of coupling is found to vary periodically with the gap between the two waveguide cores, owing to the Fabry-Perot-like behavior of the gap. Moreover, the coupling length at which one waveguide has the minimum power and the coupling length at which another waveguide obtains the maximum power are different. Further investigation reveals that such a difference is attributed to the gain provided in the low-index cores.