FTTP network can be improved in various ways. Reach of the network could be expanded, speed per wavelength could be increased and new wavelengths could be added. We will talk about wavelength-division multiplexing  for the FTTP network now.

In short period of time, after installation, we could face a problem of requirements of speeds close to 100Mbps per subscriber. Using multiple new wavelengths might help solving this problem, creating WDM-PON and satisfying all the demands. Basic idea of this network is using unique wavelength for each PON, so ONU (ONT) can send information to different clients at the same time over shared fiber.

In this network is required to have colorless ONT (ONU) , that is not assigned a fixed to a fixed wavelength. Since low cost is the main factor in PON implementation, we could not use a tunable laser at each ONT (which satisfies all the requirements but is extremely expensive).

The method of using spectral splicing of a single-broadband relatively inexpensive light source. The technique of using FP (Fabry-Perot) laser diode is an option that is described in the OFC 2005 paper.

Picture 1. A commercial Fabry-Perot device

It uses narrow spectral slices from a broadband light source to force the FP laser operate in a quasi singlemode, whereby the mode partition noise of the FP laser diode is suppressed sufficiently to allow the device to be used as a WDM source.

Please check out updated product range for our FTTH products here