Interference In Lithium Niobate-based Integrated Optical Switch

With the increasing of the complexity of the opto-electronic systems, the proportion of single device's costs in the system is increasing, it urge us to adopt photonics integration circuit (PIC) technology to improve the performance and decrease the costs of the systems. In recent ten years, the great progresses in some essential fabrication technology of opto-electronics have obtained, and these make the firmly bases of PIC technology. The progress of WDM technology, especially DWDM technology improved the progress of PIC technology, in those systems, if PIC technology is not adopted, those systems are almost impossible.Optical switch is a kind of optical device which has one or several out-parts, can shift the optical signal to one or several paths. According to the output parts numbers, optical switch can classified as 1 × 1, 1 × 2, 2 × 2 ,1XN and N × M switches. The optical switch play important role in optical communication systems and in optical process systems, act as optical-across-connections (OXCs), optical add/drop multiplexers (OADMs) and optical signal monitors. In all kinds of switches, thermo-optical switch, MEMs switch, liquid-crystal switch and air bladder switch are the trend of large-scale switch array, and Lithium Niobate electro-optical switches and electro-optical polymer switches are the trend of fast switches.In this paper, Ti: LiNbO3 interference optical switch is designed and fabricated, the aim of this study is to achieve novel structure, and good performance integrated optical device and fish out the experience of design and fabrication of Lithium Niobate devices.Lithium Niobate is a kind of ordinarily material for guide-wave devices, it can realize low modulation voltage, fast switch velocity, low material costs, simple fabrication process and it is a mature technology. At present, Lithium Niobate is applied in fast optical network and optical signal processing systems. None buffered X cut Lithium Niobate electrode structure has the smallest half wave voltage (about 70% of Z cut devices). Although it has relatively slow switch velocity, but several tens of ns is sufficient for the design requirements. As a result, we choice none-buffered X cut Lithium Niobate electrode structure to achieve the half wave voltage as low as possible. Using the method of simulation calculation and compare, we choice the structure of Y-branch balance bridge interference switch. This structure has the advantage of shortness, low voltage and less electrode number.By the method of design optimization and improvement in fabrication process, the device of good performance is achieved. Same difficulties in the fabrication process of Lithium Niobate devices, such as Ti diffusion waveguide fabrication, Ti film left-off, had overcame, and it provide the foundation for further investigation.