Low-crosstalk and thermo-insensitive CWDM (de)multiplexer assisted with compact MZIs and slot waveguides

A low-cross-talk and thermo-insensitive 1×4 coarse wavelength-division multiplexing device is proposed on the silicon-on-insulator platform with the help of compact Mach–Zehnder interferometers (MZIs) and slot waveguides. The compact MZIs are used to achieve wavelength-insensitive power splitting. In the phase shifters, the trade-off between the opposite thermo-optical coefficients of the Si core and SU8 cladding in the slot waveguide is used to overcome the strong thermo-optic effect of silicon. The simulated results show that the cross talk is less than −20dB at central wavelengths and the temperature-dependent wavelength shift is reduced to ∼4.7pm/ ∘ C. For the four channels, the 1-dB and 3-dB bandwidths are ∼14nm and ∼18nm, respectively.