Four-wave Mixing Effect Based On Novel Silicon-based Nano-devices

Because of its large bandwidth and high efficiency,on-chip four-wave mixing has become a hot research field in signal processing,quantum information and microwave photonics.Due to the mature CMOS technology and excellent photoelectric performance,silicon-based nano-photonic optical waveguide has become one of the most promising materials platforms for on-chip four-wave mixing.However,silicon is still suffering from the nonlinear absorption effects such as two-photon absorption and free carrier absorption in optical communication bands,the development of new silicon-based CMOS compatible materials is a key research focus to promote the large-scale application of on-chip fourwave mixing effect in integrated optical systems.In order to meet the requirements of microwave photonics,the four-wave mixing effect in TiO₂ waveguide devices has been studied with emphasis on providing a new onchip light source and new signal processing functions for microwave photonic systems.High quality TiO₂ straight waveguides and micro-rings have been designed and fabricated,and a series of four-wave mixing experiments have been carried out.A new Si-SIN hybrid integrated all-optical tuning device has been developed and verified,which greatly improves the energy utilization rate and provides a new method for four-wave mixing tuning and efficient intelligent re configurable integrated photonic chi p.The main research results of this paper are as follows:1.TiO₂ straight waveguide is fabricated,and the loss of waveguide with different width is measured.The nonlinear refractive index of TiO₂ waveguide is extracted through the four-wave mixing experiments,and the wide-band four-wave mixing phenomenon in straight waveguide is studied by numerically and experimentally.2.The highest TiO₂ micro-ring is achieved,and the four-wave mixing enhancement phenomenon in TiO₂ micro-ring is demonstrated for the first time,thanks to the low thermo-optical coefficient of Ti O2 mi cro-ring.In the experiment,the high-power incident light can be stably coupled into the micro-ring,and the cascaded four-wave mixing phenomenon in the micro-ring has been observed,which lays a solid foundation for the generation of Kerr optical frequency comb in TiO₂ micro-ring.3.By using the highest refractive index among common oxide materials,ultra-small micro-ring with high Q value and high power enhancement factor is prepared,which further improves the wavelength conversion efficiency.At the same time,the TiO₂ microring with high Purcell factor was prepared by giving full play to the rare-earth ion doping ability of TiO₂ micro-ring,which laid a solid foundation for the development of light source on chip.4.A new method of on-chip all-optical switch is proposed.We use the free carrier effect of silicon to tune the characteristics of the silicon micro-ring.Compared with guiding the control light at 400 nm and 980 nm through the free space optical path to the device to be regulated,we use the SiN waveguide to guide the control light that located in the silicon absorption band.The Si-SiN structure is used to realize the complete integration of control light and signal light.Compared with the method of free space optical path,the total integration method greatly improves the control efficiency.In this paper,wavelength conversion in the silicon-based TiO₂ waveguide device and on-chip all-optical switch in the Si-SiN hybrid devices are achieved,which will be ready for the following research on wavelength conversion and multi wavelength signal distribution technology based on all-optical regulation.Furthermore,these results will be useful for the design and implementation of all-optical programmable chip and microwave photonics,which will also promote the further development of silicon photonics.