Research On Thermally Tunable Bragg Grating Filter Based On The Inverted SU-8 Ridge Waveguide

In recent years,the high-definition video service in Internet has developed rapidly with the support of 5G technology.The penetration rate of mobile electronic products is extremely high and the demand for network bandwidth in Internet is also increasing rapidly.Following this,traditional electronic communications are facing huge challenges.In order to promote the development of technology,people have turned their attention to integrated optics.In integrated optics,tunable devices,which can improve the flexibility of the optical communication systems,have always attracted a lot of interests.Due to the great thermo-optical coefficient performance of the polymer materials,polymeric waveguides can be utilized for thermal tuning devices.We focus on the thermal tuning filter technology based on polymeric waveguides in this thesis.An inverted ridge waveguide is considered in this work.Firstly,the single-mode condition of the inverted SU-8 ridge waveguide is analyzed.The principle of the Bragg grating structure is discussed in detail through the coupled mode theory method.Furthermore,the Bragg grating filter is designed based on single-mode inverted SU-8 ridge waveguide.The main contents of this thesis are as follows:1.A thermally tunable Bragg grating filter based on the inverted SU-8 ridge waveguide working at 1550 nm band is designed.The device is then fabricated according to the simulation results.According to the characterization results,the inverted SU-8 ridge waveguide thermally tunable Bragg grating filter is highly consistent with the simulation results:the extinction ratio of the filter in the theoretical design reaches 28 dB,the thermal tuning efficiency is-0.1 nm/K and the 3dB bandwidth is 1.2 nm;The extinction ratio of the fabricated filter can reach about 28 dB,the thermal tuning efficiency is-0.07 nm/K and the 3dB bandwidth is 1 nm.The experimental results agree well with the theoretical simulation results.2.The blue-green light is a "transparent window" underwater which is very conducive to communication and transmission in the underwater communication.Therefore,inverted SU-8 ridge waveguide thermally tunable Bragg grating filter working at blue-green light is designed The calculation shows that the optimized blue-green light inverted SU-8 ridge waveguide thermally tunable Bragg grating filter has an extinction ratio as high as 32.5 dB,the thermal tuning efficiency is-0.032 nm/K and the 3dB bandwidth is 50 pm.