25-GHz Spaced Spectrum-Sliced WDM PON Using 50-GHz AWGs

We demonstrate a spectrum-sliced wavelength-division-multiplexed passive optical network with the channel spacing of 25 GHz, where even and odd channels are spectrum sliced separately using a pair of 50-GHz arrayed-waveguide gratings (AWGs). The 50-GHz AWGs have an offset of 25 GHz with respect to each other. Similarly, the demultiplexing is done using a pair of 50-GHz AWGs for even and odd channels separately. Our use of 50-GHz AWGs gives better bit-error rate performances than using 25-GHz AWGs in a conventional way. With 50-GHz AWGs, the channel bandwidth is increased about two times larger than using 25-GHz AWGs. Moreover, the increased spectral overlap between adjacent channels produces relatively small crosstalk since the channels are incoherent and their intensity noise is absorbed by reflective semiconductor amplifiers. The 25-GHz spaced spectrum-sliced WDM passive optical network can be realized more easily using 50-GHz AWGs since 50-GHz AWGs are more available in the market than 25-GHz AWGs.

I. Introduction

Passive optical networks (PONs) are economic solutions for broadband access networks [1], [2]. Compared with time-division multiplexed (TDM) PONs, wavelength division multiplexed (WDM) PONs can provide dedicated high capacity services such as multiple high quality videos and large volumes of data to each subscriber [3], [4]. For the implementations of WDM PON systems with low cost, spectrum-sliced incoherent channels have been investigated extensively as their optical sources [5]–[9].