Ultralow Power Consumption Silica-Based PLC-VOA/Switches

We have achieved a silica-based PLC thermooptic switch with a power consumption of only 30 mW without any deterioration in the optical properties by using a tapered narrow ridge structure. To reduce the power consumption further, we propose a novel structure, the suspended narrow ridge structure, which has the advantages of both the tapered narrow ridge structure and the already reported suspended-bridge structure. As a result, we achieved PLC-VOA/switches with excellent heat design flexibility and a power consumption of 20 mW. In addition, using the proposed the suspended narrow ridge structure, we demonstrate a 16-channel V-AWG with a compact size of 20 times 17 mm and a low total power consumption of 320 mW.

I. Introduction

The rapid increase in Internet protocol traffic has led to the need for larger scale reconfigurable optical add/drop multiplexing (ROADM), which allows the insertion (addition) and extraction (dropping) of specific wavelength channels at a network node. The basic elements of an ROADM are path selection switches and variable optical attenuators (VOAs) that equalize the optical signal levels between channels. These elements have been fabricated with different technologies and include planar lightwave circuit (PLC) switches [1]–[6], [10], micro electro mechanical system (MEMS) switches [7]–[10], and liquid crystals [10]. Of these, the silica-based PLC is a promising choice for ROADMs, because it is cost effective, highly reliable, and widely employed in practical telecommunication networks. In particular, a monolithic integrated module, which contains arrayed waveguide gratings (AWGs), VOAs, switches, taps, and monitors, is attractive in terms of cost because it does not require a complicated fiber connection between sub-modules and its assembly is simple and compact [3]–[6], [10]. These PLC switches and VOAs are normally achieved using a Mach–Zehnder interferometer (MZI) configuration and operate by employing the thermooptictic (TO) effect. With large-scale monolithic integration, there is the problem of increased driving power. A conventional 2 2 PLC switch needs more than 450 mW for switching [11]. An increase in heat divergence per unit area makes the thermal management of the module more difficult as the chip size becomes smaller. Therefore, there is a strong need for PLC-VOA/switches with a lower power consumption.