Study On The Electro-optic Sampling System For Ultrafast Electrical Signals

Thanks to the rapid development of micro/nano-electronics, optoelectronics, and micro/nano-fabrication technology, the speed of electronic devices has been steadily increasing, continually challenging the ability to measure them, especially when operating in circuits. Traditional electronic methods, limited by their intrinsic problems, are not able to accomplish this task. In our research, a new photoconductive switch, which serves as the source of ultrafast electrical signal, is fabricated using Atomic Force Microscope (AFM). The prototype of an electro-optic sampling (EOS) system is studied, designed, and constructed to measure the ultrafast signal. The key components influencing the system's overall performance are analyzed and tested, in order to develop the automatic test system.The main contents of this paper include:1. Based on comprehensive reference, the techniques used for ultrafast electrical signal's characterization are reviewed and compared.2. By analyzing the fundamental principle of photoconductive switch, the ultrafast photoconductive switch is designed, including choice of its substrate material and design of its structure and fabrication method. The output characteristic of the photoconductive switch is also calculated, theoretically.3. Based on crystal optics, the principle of electro-optic effect is analyzed, from which the principle of the EOS technique is introduced. Parameters used to evaluate the performance of an EOS system are studied.4. The structure of the EOS system is designed, including opto-mechanical delay line (OMDL), embodiment of electro-optic modulator, and lock-in detection module. User's interface is developed, using LabVIEW.5. The prototype of the ultrafast photoconductive switch is fabricated using AFM.6. The prototype of the EOS system, including the optical part and the electrical part is constructed.