Research On The Polymer Optical Waveguide Vertical Coupler For PCB Optical Interconnection

With the rapid development of the information age, the demand for communications, such as transmission rate, bandwidth has increased. However the current electronic interconnection technology is restricted by electromagnetic interference and operating frequency, and results in that it is unable to meet the requirements of high speed information processing and transmission. Optical interconnection, which uses light wave as signals carrier, is characterized by good anti-jamming, high-speed transmission and the low energy consumption. Hence, it has better performance in system with high rate and high frequency. In view of this, the optical interconnection has become a hot area of research, and the study of optical interconnection between chips or PCBs also has started at home and abroad. In this dissertation, the optical waveguide vertical coupler with total internal reflection (TIR) for PCB optical interconnection is proposed, and the design, fabrication and measurement of the proposed coupler with different TIR are investigated. The research results and the main contents are as follows:Firstly, the advantages and disadvantages of the vertical couplers with different structures are analyzed, and then the vertical coupler with different TIR is investigated by means of theoretical analysis and simulation. The vertical cavity surface emitting laser (VCSEL) and the analysis method of the basic structure (rectangle optical waveguide) of the coupler are introduced, which are widely used in optical interconnects.Secondly, the technique of fabrication of large-core rectangle optical waveguide with polymer materials Epoclad and Epocore are researched. The transmission loss of the fabricated rectangle optical waveguide is measured by using the cut-back method, and the result is 0.218 dB/cm at 850 nm.Thirdly, the technique of fabrication of vertical coupler with the different TIR is investigated. A UV exposure method with protective film in the liquid is proposed, which is simple, cheap and fully compatible with the PCB technology. And the vertical couplers with four different TIR angle are fabricated successfully by using the above method. And the finished vertical couplers have clear structure and smooth end face.Fourthly, a high-precision optical test platform is set up. Then, the coupling efficiencies of the fabricated vertical coupler with different angles are tested. The coupling efficiency at 44.7° is the largest. Moreover, it can be concluded that the tolerate angle range within the 3 dB system loss is 42° between 48°. The loss of entire device is 2.48 dB fora 2 cm length rectangle optical waveguide.Finally, in order to improve the coupling efficiency of device, the technology of plating aluminum film on the end surface is investigated theoretically and experimentally.