Compact silica waveguide wavelength-mode hybrid (de)multiplexer in C/L-band

The hybrid (de)multiplexing that combines wavelength division multiplexing (WDM) and mode division multiplexing (MDM) technologies is an efficient solution for the capacity enlargement of planar lightwave circuits. A 4-channel silica waveguide WDM-MDM hybrid (de)multiplexer working with E 11 and E 21 mode in C/L-band is demonstrated. The Y-branch with phase shifter for mode demultiplexing and two-stage MMI couplers for wavelength demultiplexing are cascaded for compact size. The beam propagation method is used in the design optimization. The CMOS compatible fabrication of hybrid multiplexer promises low-cost, large-scale manufacturing. For the E 11 mode input, the insertion losses (ILs) are measured to be 3.45 dB at λ = 1550 nm and 6.58 dB at λ = 1620 nm, respectively. For the E 21 mode input, ILs are measured to be 6.21 dB at λ = 1550 nm and 12.67 dB at λ = 1620 nm, respectively. For both E 11 and E 21 modes input, the characterized 3-dB bandwidth is larger than 61.9 nm with central wavelength at 1550 nm, and larger than 13.5 nm with central wavelength at 1620 nm. Due to the simple principle and construction, the proposed scheme can be extended to construct larger scale hybrid (de)multiplexing matrix.