WDM-PON Based on Wavelength Locked Fabry-Perot LDs

Abstract

A WDM-PON has been considered as an ultimate solution for access networks. However, there were many technical and practical issues for commercial deployment. These issues were solved with wavelength locked F-P LD and the WDM-PONs employing this optical source were commercialized. These WDM-PON systems have been deployed in Korea, Europe, and US. We reviewed wavelength locking technology and WDM-PON achievements. When we inject spectrum sliced broadband light into an F-P LD, the multimode output is changed to a quasi single mode. Then, we can use the single mode light for WDM signal transmission. The broad spectral gain of the semiconductor gain medium enables a color-free operation of WDM-PON, i.e., an identical ONT can be used for each user. The wavelength locking properties depend on many parameters; especially alignment of injection wavelength to a lasing mode; passband profile of AWG and front facet reflectivity of F-P LD. However, these dependencies can be reduced by proper design of the laser quid the injection bandwidth. Thus, WDM-PON systems have been achieved with color-free operation.