| Summary: | 碩士 === 大同大學 === 光電工程研究所 === 88 === In a typical time-resolved measurement, the relative time delay between the signal under test of sample/device and that of the system probe is adjusted by an opto-mechanical true-time-delay line. We propose a new method to replace the mechanical delay line used to adjust the relative time delay in the conventional electro-optic sampling system. By using optoelectronic phase locked loop phase shifter (OEPLL-PS), we are able to control the phase shift between pump and probe signals and lock with the same frequency standard. The maximum phase deviation is up to 623o under the change in controlling voltage of 6.6 volts, which is completely independent of operating frequency. A linear transferred function of the OEPLL-PS with responsivity of 94.3 o/volt was measured. The resolution and phase fluctuation of the OEPLL-PS can be as small as 0.036o and 0.0216o, respectively. Therefore, the novel-designed module, which exhibits the same effect of opto-mechanical delay line, has been employed to construct a novel equivalent-time electro-optic sampling system. This system can improve serious drawbacks of mechanical delay line, such as the large volume, the complication in optical path alignment, and the measurement distortion, etc. The current system exhibits maximum sampling duration of up to 1.8 periods with temporal resolution of 0.2 ps and measuring distortion of less than 10%.
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