Highly linear wavelength-tunable microring-assisted Mach-Zehnder modulator

This paper proposes a wavelength-tunable microring-assisted Mach-Zehnder modulator (MRAMZM) based on the graphene structure. The integrated graphene on the racetrack microring achieves the tunability of the working wavelength and introduces the one-cycle loss of the microring corresponding to the working wavelength. Through the analysis of the modulation characteristic curve with loss, it is determined to eliminate the second- and third-order nonlinearities. The graphene-embedded asymmetric coupling structure is used to control the coupling efficiency, and finally, the linearity of the device in the range of 2 nm (1.5543 to 1.5562 µm) is improved. The simulation result shows that when the working wavelength is in this range, the spurious-free dynamic range third-order intermodulation distortion of this modulator is about 114dB⋅Hz^2/3.