Space/wavelength-routed ATM access architecture based on cascaded programmable arrayed-waveguide gratings

Summary form only given. Wavelength routing in access networks is becoming attractive due to increased security, decreasing wavelength division multiplexing (WDM) component costs, and wider available bandwidths. In this paper, we propose a novel access architecture that addresses 1000 optical network units (ONUs) using just 100 wavelengths. The architecture incorporates cascaded coarse and fine programmable arrayed-waveguide gratings (AWGs) in the exchange, and passive non-temperature-controlled coarse AWGs at the remote nodes (RNs). Both types of coarse AWGs are designed to have near-rectangular passbands of 4-nm 3 dB width, equal to the free spectral range (FSR) of the fine AWG. This allows the same basic coarse AWG design to be replicated at the RNs or within the exchange, thus reducing costs. Each AWG has 10 output ports. The cyclic properties of AWGs have been utilized to make simple space-switching devices, controlled by applying a single voltage. The functionality afforded by the trapezoidal active region within the AWG also allows the device to be temperature stabilized by adjusting the voltage with closed-loop control.