Port Scalable PLC-Based Wavelength Selective Switch with Low Extension Loss for Multi-Degree ROADM/WXC

We demonstrate a port scalable PLC-based WSS with a low extension loss. The average insertion loss of the first four ports is 7.7 dB and the loss increment of a four-port extension is only 1.5 dB.

1. Introduction

Transparent networks with no transponders at intermediate nodes are beginning to be deployed in systems ranging from those with a ring topology with 2-degree reconfigurable optical add-drop multiplexing (ROADM) nodes to those with a mesh topology with multi-degree ROADM or wavelength cross-connect (WXC) nodes. A wavelength selective switch (WSS) is a core device for constructing such multi-degree ROADM/WXC nodes. Many types of WSS have been developed using free space technology with a micro-electro-mechanical system (MEMS) or liquid crystal [1], [2], and using planar lightwave circuit (PLC) technology [3]–[5]. PLC technology is a promising way to integrate many optical functions into a compact package. Recently we demonstrated a PLC-based 32-wavelength WSS module that provides wavelength specific ports for all local add/drop channels, individual channel level monitors and level equalizers in a single packaged module of [6].