Silicon-based Integrated Device For Electro-optic Modulation Assembly With Mode-division Multiplexing

As modern high-speed optical communication technology has more and more severe requirements for equipment performance and size,it is difficult for separated optoelectronic modules to meet this demand.Optoelectronic devices are getting highly integrated.Electro-optical modulators and mode division multiplexers as the key components of optical communication systems have been studied thoroughly at this stage.However,there are few studies on the integration of two devices.Combining the electro-optical modulator and the mode division multiplexer can reduce the overall device size,increase the communication capacity,and achieve the purpose of integration.Therefore,research on electro-optical modulation and mode division multiplexing integrated device with excellent performance is very significant for the future ultra-high-speed and ultra-large-capacity optical communication and the field of optoelectronic integration.This paper proposes a silicon-based electro-optical modulation and mode division multiplexing integrated device,which is composed of two parts:the electro-optical modulation module and the mode division multiplexing module.The electro-optical modulation module is composed of silicon-based photonic crystal waveguides and a width modulated(Width Modulated,WM)resonant cavity,and the mode division multiplexing module is composed of silicon-based asymmetric parallel nanowire waveguides.A tapered structure is used at the junction of photonic crystal waveguides and the nanowire waveguides to reduce the cascade loss between the two waveguides.According to time-domain coupled mode theory,plasma dispersion effect and transverse coupled mode theory,the narrow-band on-off modulation,two-mode division multiplexing and three-mode division multiplexing for TE0 mode,TE1 mode and TE2 mode with a center wavelength of 1553.91nm can be realized.The simulation results indicate that when the modulation voltage is 1.24 V,the extinction ratio of the integrated device is 19.73d B,the modulation depth is 0.9894,the minimum insertion loss is 0.05 d B,the maximum insertion loss is0.84 d B,the minimum channel crosstalk is-34.33 d B,the maximum channel crosstalk is-14.52 d B,and the Q value is up to 1.5×10~4.The integrated device has good performance and compact structure.It can be applied to high-speed and large-capacity optical communication systems and has important value for improving system integration.