Design And Packaging On Silicon-based Mach-Zehnder Optical Modulation Chips

With the development of silicon photonic integration technology,optical modulator chip technology based on silicon-on-Insulator(SOI)material is becoming to attract attention.This article focuses on the design,packaging,and testing aspects of the silicon-based Mach-Zehnder modulator(MZM)chips,specifically involving electro-optic MZM based on carrier dispersion effects and magneto-optical MZM based on the magneto-optic non-reciprocity principle.The main content and innovation are as follows:1.For ridge-shape SOI waveguides,the electrode models of PIN and PIP were established by using Lumerical simulation software.The effects of applied voltage on carrier concentration and thermal field distribution were simulated respectively,and the effective refractive index variation was analyzed.By optimizing the design of multi-mode interference(MMI)couplers,the cross-sectional size and length of SOI optical waveguides and the distance between MZI arms,an electro-optic MZM silicon-based chip,with the waveguide cross-section of 0.5?m×0.22?m and the modulation arm length of 1 mm,along with 60 nm-thick doped region,was finally designed and fabricated.2.The electrical and optical packaging of the electro-optic MZM chip and the development of the temperature module were implemented.According to the electrode distribution of the designed MZM chip,the PCB carrier board for the chip was designed and fabricated.The gold wire was used for electrical packaging and resistance testing.Then,the optical fiber array was used to vertically couple and fix onto the input and output gratings of the chip through ultraviolet(UV)glue.The optical test results show that the insertion loss from the input to output fiber ports is about 15 dB at the 1550 nm wavelength.The chip temperature can be monitored by means of a thermistor mounted on the chip carrier board,with the control precision of 0.03°C for the temperature control circuit.3.An experimental test platform for the electro-optical MZM chip module was built up,and the voltage signal generated by an arbitrary waveform generator(AWG)was applied to the chip PIN electrode to measure the frequency response of optical modulation.When the PIP electrode voltage is 4.1V and the signal DC bias is 0.7V,the3dB modulation bandwidth measured experimentally is 340MHz,which is mainly determined by the machining accuracy of MMI and the speed of carrier concentration change.4.A magneto-optical MZM chip is designed by using the non-reciprocal property of propagation constant in silicon-based magneto-optical waveguides,and the detailed design steps are given.By use of the Comsol software together with Matlab,the characteristics of the magneto-optical waveguide were simulated from three aspects:those of the impedance characteristic of the microstrip line,the microwave characteristics of the magneto-optical material,and the magneto-optic non-reciprocity.The frequency response of the magneto-optical MZM chip was evaluated by applying different frequency sine waves onto the microstrip line.When the bias magnetic field H_a is 900 Oe,the magneto-optical modulation bandwidth can reach 10 GHz,which may further increase with the bias magnetic field.