MODE EVOLUTION TYPE POLARIZATION SPLITTER ON INGAASP/INP

A new type of mode-evolution polarization-splitter on the basis of InGaAsP/InP is designed and realized. The component uses the large waveguide birefringence of the first-order TE and TM modes in a ridge waveguide made in a heterostructure. In the input section an asymmetric Y-junction acts as a mode converter in order to inject first-order TE- and TM-modes in a polarization-splitting section, which consists of a Y-junction formed by a bimodal and a monomodal waveguide. In the output section a third Y-junction is connected to the bimodal waveguide to couple the first-order mode to a monomodal output waveguide. Components are realized which are 6 mm-long and show polarization splitting at a wavelength of 1.55 mu. Best splitting ratios are close to -20 dB, which is in agreement with BPM-simulations. Excess losses are below 1 dB.