實驗示範60G赫兹系統之倍頻的Tandem Single-Side Band調變架構

Abstract

所提出的架構證實為長程60G赫茲光纖擷取系統可行的方法。在此架構中，我們使用倍頻的修正型Tandem單邊帶調變技術示範一個60G赫茲頻段的系統。符號率每秒1.25G的單載子4-相位偏移調變(QPSK)訊號，符號率每秒781.25M的單載子8-正交振幅調變(8QAM)訊號，總共88個次載子且每個次載子編碼載入78.125M赫茲之QPSK的正交分頻多工(OFDM)訊號被用來當作下行的訊號。由於修正型Tandem單邊帶調變技術的關係，沒有色散所造成之訊號時強時弱的情形，高頻譜響應的向量訊號可被使用且波長的重複使用也可達到。經50公里單模光纖傳輸，所試驗的訊號在接收端的能量沒有明顯的損耗。使用反射半導體光放大器傳送1.25-Gb/s的開關鍵控(OOK)上傳信號也被實驗示範出來。經50公里單模光纖傳輸，上傳的OOK訊號在接收端之能量也沒有明顯的損耗。

The proposed scheme proves to be a viable solution for long-reach 60-GHz radio-over-fiber (RoF) system. In the scheme, we demonstrate a 60-GHz band RoF system using a modified tandem single sideband (TSSB) modulation scheme with frequency doubling. Single carrier QPSK signal with 1.25-GBaud symbol rate, single carrier 8 quadrature amplitude modulation (QAM) signal with 781.25-MBaud symbol rate, orthogonal frequency division multiplexing (OFDM) signal with total 88 subcarriers and each subcarrier encoded with 78.125 MHz quadrature phase shift keying (QPSK) symbol have been demonstrated to be downlink signal. Because of the modified TSSB modulation scheme, no dispersion induced fading is observed; high spectral efficiency vector signal can be utilized; and wavelength reuse is also achieved. After 50km standar single mode fiber (SSMF) transmission, there are no significant receiver power penalty of the demonstrated signals. A 1.25-Gb/s on-off keying (OOK) signal uplink transmission is also experimentally demonstrated using a reflective semiconductor optical amplifier (RSOA). There is also no significant receiver power penalty of the uplink OOK signal with 50km SSMF transmission.