Research On Acousto-optic Devices Based On One-dimensional Photonic Crystal Defect Structure

With the continuous development of mobile communication services such as artificial intelligence,cloud computing and 5G,the requirements of communication network are higher and higher,and the devices in the communication network are also playing an increasingly important role.Optical switch and optical filter are important devices in optical communication network.They play a key role in wavelength division multiplexing,wavelength selection and device testing.One dimensional photonic crystal has excellent photonic band gap and photonic local characteristics,which is easy to be integrated and fabricated.It can be used to fabricate optical signal processing devices.Acousto-optic crystal is a kind of crystal material with acousto-optic effect.Its refractive index and thickness change through the action of sound wave.It can be used to make piezoelectric transducer,acousto-optic switch,acousto-optic filter and other excellent acousto-optic devices.Based on the acousto-optic effect of one-dimensional photonic crystal defect structure,optical Tamm state acousto-optic switch,tunable flat top filter and fully tunable acousto-optic filter are proposed and studied in this paper.The specific research work is as follows:(1)Based on the acousto-optic effect,an optical Tamm state acousto-optic switch based on onedimensional photonic crystal heterojunction is proposed.The theoretical model of acousto-optic switch is established,and the tunable performance of acousto-optic switch under the action of ultrasonic waves with different amplitudes or frequencies is studied.At the same time,the extinction ratio,insertion loss and response time of the switch are analyzed.The results show that the OTS intrinsic wavelength of the AOS will shift to the short wave direction under the action of ultrasonic wave,the extinction ratio can reach 13.17 db,the insertion loss is the lowest,only 0.99 db,and the response time is no more than 13 ns.Compared with the existing acousto-optic switches,the acoustooptic switch has higher extinction ratio,lower insertion loss and more advantages,which can be effectively applied in the future optical communication.(2)Based on the acousto-optic effect,an optical Tamm state acousto-optic switch based on onedimensional photonic crystal heterojunction is proposed.The theoretical model of acousto-optic switch is established,and the tunable performance of acousto-optic switch under the action of ultrasonic waves with different amplitudes or frequencies is studied.At the same time,the extinction ratio,insertion loss and response time of the switch are analyzed.The results show that the OTS intrinsic wavelength of the AOS will shift to the short wave direction under the action of ultrasonic wave,the extinction ratio can reach 13.17 db,the insertion loss is the lowest,only 0.99 db,and the response time is no more than 13 ns.Compared with the existing acousto-optic switches,the acoustooptic switch has higher extinction ratio,lower insertion loss and more advantages,which can be effectively applied in the future optical communication.(3)Based on the acousto-optic effect,a fully tunable acousto-optic filter based on onedimensional photonic crystal heterojunction is proposed.The theoretical model of fully tunable acousto-optic filter is established.The influence of ultrasonic waves with different amplitudes or frequencies on the central wavelength of acousto-optic filter is studied.The insertion loss,machining accuracy and other performance parameters of acousto-optic filter are analyzed.The results show that the tuning range of the central wavelength of the filter is 1478-1500 nm and the tuning range of the passband bandwidth is 4.5-8nm when the thickness of the air defect is not changed by ultrasonic,while the tuning range of the central wavelength of the filter is 1500-1556 nm when the thickness of the air defect is not changed by ultrasonic.The central wavelength tuning range of the filter is 1478-1556 nm,and the bandwidth tuning range is 4.5-8nm.The insertion loss range of the filter is 0.99-1.68 db when ultrasonic is applied.The insertion loss range of the filter is 0.78-2.37 db when ultrasonic is not applied.It can accept a certain degree of processing error.It can be applied to spectrum analysis,wavelength division multiplexing,all-optical communication network with high-speed dynamic routing,etc.The optical switch and optical filter based on acoustooptic effect are easy to integrate,simple in structure,easy to prepare,excellent in performance and tunable in central wavelength.It has potential application value in the field of optical communication devices.