FTTH based on Gigabit Ether Passive Optical Networks(G-EPONs) has been spreading steadily in Japan. The focus of
the near term developments in optical access technology will shift to support the migration from working PON systems
to next generation access (NGA) systems. New technologies for 10 Gbit/s TDM access and WDM access are being
extensively investigated to realize higher capacity and/or new services cost effectively on the existing PON fiber
infrastructure while customers continue to receive legacy services. This paper describes the key technologies being
investigated for such future optical access systems that can be installed seamlessly over working PONs.
In this paper, we propose a wavelength locker free, simple and cost effective wavelength setting and monitoring method that estimates wavelength on a software basis. This method uses preliminarily measured wavelengths at selected sets of drive current and device temperature, which are stored in the memory of the transceiver module. We then determine the relationship among the wavelength, the drive current, and the device temperature as a linear function. This function enables us to estimate the wavelength by setting and monitoring the drive current and device temperature. The same procedure is done for output power estimation. We measured the wavelength estimation accuracy using two practical DFB-LDs and confirmed that the discrepancy between the estimated wavelength and the measured wavelength was less than ±1 GHz.
Fiber to the home (FTTH) is now the most popular fixed Internet access service in Japan; it has been attracting far more
customers than ADSL since early 2005. Gigabit-capable passive optical networks (PONs) have been proven to be the
most promising approach since they realize not only point-to-multipoint bidirectional connections for broadband data
communication but also video distribution in a very cost effective manner. This paper first reviews such PON
technologies as well as other optical technologies to support the massive deployment of these PONs in terms of further
reducing the cost, especially with regard to operation/installation and to further increasing user friendliness towards the
full-scale FTTH era. It next discusses possible technical directions for future optical access networks (OANs), and
review recent research towards them. Wavelength-division multiplexing (WDM) is one of the important technologies in
realizing the future OANs.