Research On Silicon-based Arrayed Waveguides Grating

In recent years,with the exponential growth of data traffic in global communication networks,the requirement of high-speed data transmission has become increasingly strong.Optical communication technology has been well developed for its advantages such as large capacity,low cost,fast speed,and anti-electromagnetic interference.In addition to high-performance lasers,amplifiers,and optical fibers used for long-distance communication,photonic integration technology that can integrate various switching and router components onto a single chip has also been rapidly developed for the short-distance communication,such as the optical wavelength division multiplexer used in the WDM system.Compared with other wavelength division multiplexing technologies,the arrayed waveguides grating has the advantages of mass production,small size,and large number of channels.There are many materials have been used to make arrayed waveguides gratings.Although arrayed waveguides gratings made with material with low refractive index differences have the advantages of low insertion loss and low crosstalk,platforms with high refractive index differences,such as silicon on insulator(SOI),has the advantages of strong light confinement to achieve smaller sizes.In addition,SOI platform is compatible with CMOS processes,which means it can be integrated with other silicon-based devices.This paper focuses on the theoretical and experimental research of arrayed waveguides grating based on silicon nitride and SOI platforms.First the principle and the design flow of arrayed waveguides grating is summarized based on the grating equation,dispersion equation,and FSR expression.An 8-channel arrayed waveguides grating with 3.2 nm channel spacing was designed based on the SOI platform,and the simulation model of the SOI based arrayed waveguides grating was established to optimize the insertion loss,crosstalk,etc.Simulation results show that an insertion loss of2.39 d B,crosstalk of-11.3d B,and channel non-uniformity of 0.358 d B were obtained and flatten spectrum was achieved by using parabolic taper;Then the layout of the arrayed waveguides grating was drawn according to the optimized parameters.Finally,the arrayed waveguides gratings were fabricated and measured.The measured insertion loss,crosstalk,and channel non-uniformity were 3.588 d B,-13.485 d B and 2.627 d B,respectively.Moreover,an 8-channel arrayed waveguides grating with channel spacing of 0.8 nm was designed based on the silicon nitride platform.A simulation model of the silicon nitride arrayed waveguides grating was also established to optimize the insertion loss and crosstalk,etc.The spectrum flattening was achieved using a MMI structure and insertion loss of 1.3d B,crosstalk of 8.7d B,non-uniformity of 0.6d B were obtained after optimization.Finally,the corresponding layout of the optimized silicon nitride arrayed waveguides grating was drawn.