Keywords: PON; WDM-PON; OFDM  
1. Introduction  
2. Conventional PON architecture and terminology  
3. WDM-PON  
4. OFDM-based PON  
5. Wavelength reused WDM-PONs using RSOAs  
6. OFDM WDM-PON based on RSOA  
7. Conclusion