Polarization-Insensitive Arrayed-Waveguide Grating Multiplexer with Polymide Waveplate as TE/TM Mode Converter

Integrated-optic arrayed-waveguide grating multiplexers are expected to find many applications in the construction of wavelength-addressed transmission and switching systems. Several approaches have already been reported which achieve polarization- insensitive multiplexer operation[1][2][3] Among them, the TE/TM mode conversion method, in which a half waveplate is inserted in the center of the arrayed-waveguide region, seems to be most practical, since this method is applicable to any waveguide, irrespective of its birefringence value. One problem with this method, however, is the large excess loss due to the waveplate insertion; a loss as large as 5 dB was reported with a 92 pm-thick quartz waveplate in a silica-based arrayed-waveguide multiplexer.[1]