本論文是以雙向全光式訊號調變模式轉換為主軸，分別進行模擬與實驗的部分。以高非線性光纖(Highly nonlinear fiber；HNLF)為非線性介質，透過四波混頻(Four wave mixing；FWM)的機制分別將BPSK訊號與45°PSK訊號作用，轉成QPSK訊號；QPSK訊號與CW(Continuous wave)作用，轉成BPSK訊號。
在FWM的過程中，我們以10-Gb/s的45°PSK訊號作為pumping light而10-Gb/s BPSK訊號作為probe light，作用後轉出來的QPSK訊號為idler light，其光訊雜比(Optical signal to noise ratio；OSNR)約為30 dB且位元錯誤率(Bit error rate；BER)可達10-4；而另一個方向為20-Gb/s的QPSK訊號作為pumping light而CW為probe light經由非線性效應轉出來的BPSK訊號為idler light，其OSNR約為25 dB且BER也可以達到10-4。

In this thesis, we propose and experimentally demonstrate an all optical PSK format conversion in a bi-directional scheme using four-wave mixing (FWM) effect in highly nonlinear fiber (HNLF). In the FWM process, a 20-Gbits/s quadrature phase-shift keying (QPSK) signal and a continuous wave (CW) are utilized as pumping light and probe light, respectively. A 10-Gbits/s binary phase-shift keying (BPSK) signal, which is the idler light, is successfully obtained with optical signal-to-noise ratio (OSNR) about 25 dB and bit-error rate (BER) lower than 10-4 . Similarly, a 10-Gbits/s 45°PSK signal is used as pumping light and a 10-Gbits/s BPSK signal is used as probe light. After FWM process in a HNLF, a 20-Gbits/s QPSK signal, which is the idler light, can be obtained with OSNR about 30 dB and BER lower than 10-4 .

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