Research On Design,fabrication And Test Of Silicon-Organic Hybrid Integrated Electro-Optical Modulator

Microwave photonic technology has broad application prospects in the fields of new generation radar systems,broadband wireless access networks and ultra-wideband microwave photonic signal processing.The electro-optical modulator is one of the core components of high-speed optical fiber communication systems and ultra-wideband microwave photonic systems.Its main function is to modulate digital electrical signals or high carrier frequency analog electrical signals onto optical carriers for optical domain transmission or processing.The silicon-organic hybrid photonic integration technology combines CMOS-compatible silicon photonics processing technology and the high electro-optic coefficient characteristics of polymer materials.This accords great application potential in high-performance integrated microwave photonic system to it.In this paper,the optimization design,preparation,processing and experimental test of the silicon-organic hybrid integrated electro-optic modulator are carried out in-depth research.Firstly,the waveguide and electrode structure of the modulator are designed and optimized.The optical field confinement factor reaches 13.7%by optimizing the structure of Slot waveguide.The optical field and the RF electric field overlap considerably,which improves the electro-optic modulation efficiency.The Taper type and MMI type mode converter structure are optimized to achieve the low-loss coupling between the Strip waveguide and the Slot waveguide with the coupling efficiency of 99.6%and 94.1%,respectively.The modulator frequency response is addressed by analyzing influence of electrode thickness,gap,length and width.The 3d B bandwidth is optimized to 77GHz and the half-wave voltage-length product reaches 0.089V·cm.Large modulation bandwidth,low power consumption and high integration can be achieved at the same time.Then MASK for manufacturing the modulator is designed according to the optimization results and the actual test situation.The preparation process flow of silicon-organic hybrid integrated electro-optic modulator chip is researched and given.The electron beam etching process is used to prepare the Slot waveguide with a slit width of one hundred nanometers and the Slot waveguide structure with good morphology is obtained.Finally,the whole tape-out process is completed and the modulator chip is obtained.Next,the modulator chip is tested for light-passing and electro-optic modulation effects.The experimental measurement shows that the input and output vertical coupling loss of fiber-to-grating is about 9.36d B,the on-chip loss of the Taper type mode converter is as low as0.64d B.The modulators with better light-passing are filled with electro-optic polymer and polarized.The on-chip polarization electro-optical modulation effect test system is built and a commercial modulator is used to verify the feasibility of the test scheme.Finally,the performance improvement scheme for the spurious free dynamic range of microwave photonic links based on dual-parallel Mach-Zehnder modulator is studied.The basic theory of non-linear intermodulation distortion is analyzed and the optimal relationship of the three bias voltages of the modulator is obtained.By reasonably adjusting the three bias voltage values,the third-order intermodulation component can be effectively suppressed,and a large spurious free dynamic range can be obtained.The influence of bias voltage deviation,input optical power and modulator insertion loss on the spurious-free dynamic range is analyzed by simulation.The voltage deviation is within the range of±0.72V,and the spurious free dynamic range can reach more than 110d B·Hz^2/3.The research results provide an optimized scheme for the realization of the on-chip high-linearity microwave optical modulation function,chip preparation and test.