Planar light-wave circuit-based switchable LP11a-LP11b mode rotator.

A simple planar light-wave circuit-based switchable LP11a-LP11b mode rotator for reconfigurable mode division multiplexing is proposed, which consists of a polymer waveguide and an electrode heater located on the waveguide. Because of the asymmetric refractive index distribution in the horizontal and vertical directions, induced by the thermo-optic effect, mode rotation between the LP11a and LP11b modes can be achieved when the heater is ON but there can be no mode rotation when the heater is OFF. Numerical simulations show that our well-designed mode rotator with optical polymer materials, which has a length of 2750 µm, can achieve a mode conversion efficiency (MCE) larger than 84% over the entire C+L band (1530-1610 nm) and a maximum MCE of 96% at 1550 nm. The switching electric power is 161.5 mW. The calculated temperature within the waveguide core is from 186°C (close to the heater) to 86°C (away from the heater).