Broadband and compact reconfigurable polymeric thermo-optic mode converter based on cascaded Y-junctions

We propose and demonstrate experimentally a thermo-optically reconfigurable mode converter based on cascaded Y-junctions on a polymer waveguide platform. The proposed device, which can achieve reconfigurable mode conversion between the LP01 and LP11a modes, features compact, broadband, and low-power. Our typical fabricated mode converter has a footprint of 1.5 mm x 66.2 mu m. The power consumptions of each heater for achieving the LP01-to-LP11a and LP11a-to-LP01 mode conversions are 32 mW and 28 mW, respectively. The mode crosstalks are as low as-20.7 dB and-18.9 dB for the x-and y-polarized LP01 modes over the wavelength range of 1530-1600 nm, respectively. Our proposed mode converter could find applications in reconfigurable mode -division multiplexing optical communication systems.