| Summary: | 碩士 === 大同大學 === 光電工程研究所 === 90 === A novel real-time electro-optic sampling oscilloscope system with a delay-time tunable pulsed laser source is demonstrated. A voltage-controlled digital electronic phase shifter (DEPS) integrated with the pulsed laser is employed to substitute the opto-mechanic delay line for continuous tuning the delay-time of optical pulse-train in the EOS system. The maximum scanning speed, delay-time, tuning responsivity, and resolution of the DEPS are 100 point/sec, 3.56 ns (1.78 periods), 0.508 ns/volt, and 0.2 ps, respectively. This system further benefits the advantages of frequency tracking to free-running signals with suppressed timing-jitter. The SSB phase noise at 1 kHz offset from the carrier of the VCO phase-locked to the RFS can still be as low as —90 dBc/Hz. However, the probe beam 3dB pulsewidth of GSLD was 18 ps. The SSB phase noise of the GSLD was -70 dBc/Hz at 100Hz which is similar to the VCO SSB phase noise offset from the carrier frequency, and the timing jitter of GSLD will saturate to 1.2 ps as the frequency offset from carrier over 1 kHz. By using this system, the waveforms of microwave signals generated from a frequency synthesizer, and frequency divider are real-time sampled by showing on a sample oscilloscope. The main advantage of the real-time EOS oscilloscope is the decreasing in sampling time, which eventually prevents sampling distortion caused by the fluctuation in both the power and pulsewidth of GSLD during long-term operation.
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