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林勇勳,徐東善,朴鐘大 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-
We generate short optical pulses of ~ 8 picoseconds at 10 GHz by chirped pulse compression based on phase modulation and chirp compensation. In the suggested method, sinusoidally driven intensity and phase modulators generate chirped pulses which are subsequently suppressed by chirp compensation using a single mode fiber.
2 GHz 이득 스위칭 광 펄스의 다중 모드를 이용한 40 GHz의 광 펄스열 생성 및 안정화
趙衍秀,李明雨,朴鐘大,徐東善 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-
We generated multi-mode optical pulses of 2 GHz repetition rate by gain switching FP laser and then used DCF(dispersion compensation fiber) to separate mode of 40 GHz optical pulse trains by time. After passing them through SFRL(semiconductor fiber ring laser), the generated optical pulses turn into stabilized 40 GHz optical pulses..
40 GHz 대역에서 프라임 부호를 이용한 RoF 시스템용 DOS-CDMA 실험적 연구
崔宰源,全榮民,朴鐘大,徐東善 明知大學校 産業技術硏究所 2004 産業技術硏究所論文集 Vol.23 No.-
In this paper, we propose and demonstrate a future wide band mobile communication technology based on millimeter-wave Direct Optical Switching CDMA (MMW DOS-CDMA) in Radio-over-Fiber system. This DOS-CDMA system uses millimeter waves in 40 GHz bands as its carrier waves, which is much higher than the frequencies of several GHz used in the existing mobile communication technology. Orthogonal codes used in the encoding and decoding in CDMA have two types: prime code and unipolar code. Unipolar orthogonal code is used to eliminate padding chip. The code lengths and chip rates of the two orthogonal codes were 16 chips and 2.5 Gchip/sec, respectively. We selected code sequences with cross-correlation less than 2. Pulse-amplitude-equalized 40 GHz laser pulses were provided by rational-harmonically mode locked a 10 GHz fiber ring laser. By experiments, the RF spectra of the decoded optical signals and the optical interference noises showed noise suppression of 20 dB. However, CIR (Carrier-to-Interference power Ratio) raised to 45 dB after 40 GHz filtering of the decoded optical signals. Moreover, since the code frequency was 156MHz (2.5 Gcps/16), MMW signal bandwidth was as large as 78 MHz without spectral aliasing canceling.