상호 주입된 페브리 페롯 레이저 다이오드를 이용한 WDM-PON 시스템에서 OFDM 기반 방송 신호 전송

Abstract

Recently, a wavelength division multiplexing passive optical network (WDM-PON) has been attracted as a next generation access network because of its large bandwidth, high security, bit rate and protocol transparencies. However, WDM-PON cannot provide broadcast services efficiently because of virtual point-to-point connectivity. To solve this drawback, several broadband light sources (BLSs) for transmitting a broadcast signal have been proposed such as a Fabry-P´erot laser diode (F-P LD) with broadband amplified spontaneous emission (ASE) light injection and a mutually injected F-P LDs (MI F-P LDs). MI F-P LDs is especially has a low relative intensity noise (RIN) compared with other light source and 2.5 Gb/s data transmission which use Manchester code and high/low pass filter has demonstrated. In this thesis, we verify the feasibility of 10 Gb/s broadcast signal transmission with orthogonal frequency division multiplexing (OFDM) technique and the MI F-P LDs. Since RIN of MI F-P LDs has periodic peak, signal transmission only using low RIN region is required. 10 Gb/s broadcasting signal transmission can be achieved by adopting 0.65 GHz null band and 4 QAM conventional modulations. OFDM signal has high peak-to-average ratio and it is distorted severely during external modulation. To minimize the distortion, electrical signal should be scaled and the optimum peak-peak voltage was 7.42V. Even though transmission length can be increased by using dispersion compensating module, nonlinearity such as self phase modulation should be considered to increase the power budget. To achieve BER 10^-12, maximum transmission distance was 140 km and the transmission distance can be increased to 160 km in case of using forward-error correction.