Research On Electro-optic Modulator And Switch Based On Silicon Microring Resonators

In the past few decades,silicon-based electro-optics has grown considerably.Silicon is widely used in large-scale integrated electrooptical transmission systems due to its low cost,mature technology and good stability.The reason why silicon was chosen as the material platform for optoelectronic devices was silicon-based microelectronics technology has made remarkable achievements and promoted the development of information technology.The trillions of dollars in investment in the world and decades of accumulation have made silicon-based processes have strong industrial capabilities.In the past decade,a variety of silicon-based electro-optic devices have emerged,including: low-loss waveguides,pump lasers,optical amplifiers,electro-optic modulators,all-optical modulators,logic gates,photodetectors,etc.Devices can be integrated into a single chip through the process.As a converter for electrical signal optical signals,siliconbased electro-optic modulators have become an important component of electro-optical transmission systems.At present,from the structural point of view,commonly used silicon-based electro-optic modulators are divided into two types,one is electro-optic modulator based on the MachZehnder interferometer(MZI),and the other is electro-optic modulator based on the micro-ring resonator(Microring resonator,MRR).Among them,the MZI electro-optic modulator has large working bandwidth and is insensitive to temperature fluctuation,low modulation voltage and highspeed modulation,but its device size is large,generally in several mm,which is not conducive to the integration of silicon-based optoelectronic devices.The MRR-based electro-optic modulator can be ?m-sized,and the power consumption is lower than that of the MZI modulator,which has attracted the interest of many researchers,but the MRR modulator has a small optical bandwidth and the resonant wavelength is vulnerable to temperature which is not conducive to large-scale production.With the explosive growth of network information,larger-scale switching systems are needed to meet the demand for information transmission.Optical interconnect is an important development direction of high-speed information transmission between computer chips.Switch is the basic unit device of optical switching system.In order to meet the development needs of optical switching systems,optical switches need to achieve small size,low power consumption,large bandwidth,high frequency,stable and so on.On this basis,this paper studies silicon-based electro-optic modulators and optical switches based on silicon microring resonators.Firstly,the device structure,device principle and device advantages are theoretically explained.Then,the chip processing technology and chip test results are introduced.The research work of this paper is:1)Electro-optic modulator based on silicon-based microring resonatorSilicon-based electro-optic modulators are a fundamental component of silicon-based integrated optical transmission systems.MZI modulators and MRR modulators have been published in the paper.Among these published papers,the MRR type modulator has attracted much attentions due to its compact structure and low power consumption.In order to achieve a high signal-to-noise(SNR)of the transmission system,the modulator needs to have lower insertion loss and higher modulation depth.In order to reduce the insertion loss of the MRR modulator and increase the modulation depth of the MRR modulator,we have studied a dual-ring electro-optic modulator based on a silicon microring resonator.The structure consists of two parallel micro-ring resonators and two parallel straight waveguides.Light is coupled into the device from the input port of the straight waveguide.When the input light resonate only with one of the micro-ring resonators,the transmission spectrum of the device is same to a single microring resonator;when the input light resonates with both microring resonators,the two microring resonators form a Fabry-perot(FP)resonant cavity.Light propagating in a waveguide between two microring resonator rings.As a characteristic of the FP cavity,the transmission spectrum of the microring resonator will have a peak at the resonance wavelength similar to the FP mode,and the FP cavity resonance peak is selected as the operating wavelength of the double loop modulator,so that low insertion loss and high extinction ratio can be realized.The experimentally measured dual-ring modulator based on a silicon-based microring resonator has a minimum insertion loss of 1.1 d B,and the corresponding extinction ratio is 7.6 d B.2)Optical switch based on silicon-based microring resonatorThe optical switch is an important component of the optical network transmission system.In order to meet the information transmission requirements,the optical switch needs to realize: low insertion loss,low crosstalk,small size,and high process tolerance.The MZI optical switch has the advantages of large bandwidth and temperature insensitivity,but its size is large;the MRR type optical switch has a compact structure and low power consumption,but has a small bandwidth.In order to reduce the size and power consumption of optical network transmission systems,we have studied 4*4 optical switches and 16*16 optical switches based on silicon-based microring resonators.In the unit optical switch structure,the MRR optical switch is selected: Compared with the MZI optical switch,the MRR switch has a small size,which can reduce the volume and power consumption of the optical network transmission system.In the optical switching topology,the Benes network structure is selected: compared with other non-blocking topologies,the Benes network structure requires fewer switching units,which can further reduce the size and power consumption of the optical network transmission system.At the same time,in order to increase the working bandwidth of the optical switch,a dual-ring resonator is used.The size of the experimentally demonstrated 4*4 optical switch and 16*16 optical switch are: 3414 ?m * 2617 ?m and 11500 ?m * 5280 ?m,respectively.The thermal-optic modulation efficiency of the dual-ring resonator is 0.057 nm/mW,and the electro-optic modulation efficiency is 0.034 nm/mW.