基于SOI的一维光子晶体纳米梁腔电光调制器

Design of SOI-based one-dimensional photonic crystal nanobeam cavity electro-optic modulator

随着光通信和光互联的高速发展,研究调制速率高、器件尺寸小且易于集成的电光调制器具有重要意义。提出了一种基于Si绝缘体材料(silicon-on-insulator,SOI)的一维光子晶体纳米梁腔(photonic crystal nanobeam cavity,PCNC)侧耦合电光调制器。根据时域耦合模理论,通过主线波导与一维光子晶体纳米梁腔形成侧耦合结构。采用圆柱型渐变孔径的一维光子晶体纳米梁腔,使光束更好的束缚在腔内,调整纳米梁腔的结构参数,使其工作在通信波段波长。同时,根据自由载流子色散效应,在纳米梁腔两侧引入掺杂形成p-n结,施加较低偏压调节纳米梁腔的谐振波长,从而实现对工作波长光信号的"通""断"调制。应用三维时域有限差分法(3D-finite difference time domain,3D-FDTD)对调制器光学特性和电学性能进行仿真分析。结果表明,该电光调制器可以实现波长为1550.55 nm的光信号调制,调制电压仅为1.175 V,插入损耗为0.04 dB,消光比为18.2 dB,尺寸仅为25μm^(2),调制速率为8.3 GHz,调制带宽可以达到90 GHz,可应用于集成光子器件及高速光通信领域。

With the rapid development of optical communication and optical interconnection,it is of great significance to study electro-optic modulators with high modulation rate,small device size and easy integration.Based on silicon-on-insulator(SOI),a one-dimensional photonic crystal nanobeam cavity(PCNC)side coupled electro-optic modulator is proposed.According to the time-domain coupled mode theory,bus waveguide and one-dimensional photonic crystal nanobeam cavity form side coupling structure.The one-dimensional photonic crystal nanobeam cavity with cylindrical tapered aperture enables better confinement of light beam in the cavity.By adjusting the structural parameters of the nanobeam cavity,the working wavelength within the communication band is selected.At the same time,according to the free carrier dispersion effect,doping is introduced on both sides of the nanobeam cavity to form p-n junction,which enables the resonant wavelength of the nanobeam cavity to be adjusted when a lower bias is applied,thus realizing the"on"and"off"modulation of the working wavelength light signal.Three-dimensional finite difference time domain(3 D-FDTD)is used to analyze the optical characteristics and electrical performance of the modulator.The results show that the insertion loss and extinction ratio of the electro-optic modulator with a compact size of only 25μm^(2)and a low modulation voltage is only 1.175 V at the operating wavelength of 1550.55 nm are 0.04 dB,18.2 dB,respectively.The modulation speed is 8.3 GHz and modulation bandwidth can reach 90 GHz,which can be appliedto integrated photonic devices andhigh-speed optical communications field.