本論文提出使用10G/s低調變頻寬之直調雷射結合光頻譜濾波器，以達到25Gb/s傳輸效能。針對法布里-比洛析光器及可調式光濾波器兩種光頻譜濾波器，使用光學模擬軟體進行模擬，並以實驗驗證單路25Gb/s傳輸的性能，接著使用具週期性頻譜特性之析光器，實現四路不同波長之直調雷射傳輸，以應用於總傳輸位元率達100Gb/s的分時多工被動光網路。
由於本論文實驗上使用10Gb/s直調雷射，頻率響應不足傳輸25Gb/s，利用光頻譜濾波提升傳輸位元率及距離的主要原理為，利用直調雷射產生出之頻率調變，經析光器頻譜整形後提升明滅比，並將頻譜響應中的相位變化轉為振幅調變，因而可提升調變頻寬，同時降低光纖色散之影響，使25Gb/s的可在單模光纖傳輸達二十至五十公里距離。且藉由析光器之穿透與反射功率具波長相依之特性，實現直調雷射之波長栓鎖機制，在不須更動網路MAC層的情況下，提升系統架構穩定度。另析光器可同時對等波長間距之陣列雷射同時進行頻譜整形及波長栓鎖，可在較低成本的情況下實現時多分工被動光網路系統。

We proposed a spectrum reshaping scheme for single-channel 25Gb/s transmission over 20-50km single mode fiber (SMF) by using a 10Gb/s direct modulation laser (DML) with insufficient modulation bandwidth. We compared the effects of two reshaping filters, Fabry-Perot (FP) Etalon and Gaussian shape tunable filter. Both simulation and experiments were carried out to investigate the effectiveness of this scheme. The reshaping filter could cause three effects. The first effect is to convert the frequency modulation (FM) to amplitude modulation (AM) and get a higher Extinction Ratio (ER). The second one is to induce an extra phase shift because of the nonlinear edge slope and reduce the intersymbol interference (ISI) caused by dispersion. The last one is to increase the modulation bandwidth, similar to the function of an equalizer.
We used the periodic spectral characteristic of an optical etalon to reshape four wavelength-channels simultaneously. Thus, we can realize a transmission of 100 Gb/s total capacity over 20-50km SMF that can be used in splitting ratio of 1:128 time- and wavelength- division multiplexed passive optical network (TWDM-PON) systems. Moreover, the wavelength locking mechanism can also be implemented by the using the same optical etalon in our architecture. We can detect the alteration of the transmission and reflection optical powers of the reshaping filer when the laser wavelength drifts. This mechanism can ensure the system stability without changing the MAC layer.

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