40-Channel Ultra-Low-Power Compact PLC-Based ROADM SubsystemLouay Eldada, Junichiro Fujita, Antonije Radojevic, Tomoyuki Izuhara,Reinald Gerhardt, Jiandong Shi, Deepti Pant, Fang Wang, Ali MalekDuPont Photonics Technologies100 Fordham Road, Wilmington, MA 01887p 978.203.1300, f 978.203.1299, louay.eldada@usa.dupont.comUntil recently, reconfigurable optical add/drop multiplexer (ROADM) systems did not exist, their components were unselected, and their market was unclear. Today, every major system vendor has a ROADM offering, and a large number of component and subsystem vendors have announced ROADM products based on a variety of technologies, some more mature than others.We will start the full manuscript and the talk by reviewing the different optical component technologies that have been developed for use in ROADM subsystems, and describe their principles of operation, designs, advantages, and challenges. The technology platforms that we cover include MEMS, liquid crystals (liquid crystal display (LCD) and liquid crystal on silicon (LCoS) technologies), and monolithic and hybrid planar lightwave circuits (PLC) based on silica on silicon and polymer on silicon.We propose a 40-channel ultra-low-power compact PLC-based ROADM subsystem (Fig. 1).The ultra-low power consumption is achieved mainly through the use of:- Polymer-based dynamic components, including switches and variable optical attenuators (VOAs). The polymer exhibits a thermo-optic coefficient dn/dT of 3.2x10-4 in absolute value, a value that is 32x larger in absolute value than that of silica, resulting in a power consumption that is 32x smaller than that of silica.- Athermal-AWG-based multiplexers/demultiplexers (mux/demux). These AWGs are produced in silica on silicon, consume no electrical power, and exhibit a wavelength temperature stability that is better than ±0.3 pm/°C from -30 to 70°C. We will describe the principle of athermalization.The total power consumption of this subsystem (for both the optical components and the electronic controls) is 5 W.The compact size is achieved by using:- Compact polymeric chips enabled by compact device designs, and dense packing of the devices on the chip, without thermal dissipation or thermal crosstalk issues, because of the large thermo-optic coefficient of the polymer.- Integrated photodiodes (IPD), flip-chip mounted on taps in the polymer chips, allowing significant space savings on the PCB compared with traditional external tap/PD.- Chip-to-chip attachment of polymer-based switch/VOA/tap/IPD chips and silica AWG chips, minimizing the number of components and fiber splices in the subsystem.This compact 40-channel ROADM subsystem fits within a single-slot blade.Additional performance characteristics include low insertion loss (7 dB), low PDL (0.5 dB), high VOA dynamic range (20 dB), high switch isolation (50 dB), and low crosstalk (-50 dB). Furthermore, the athermal AWGs have flat-top low-ripple passbands, enabling cascadibility of 16 ROADM nodes in a ring network.A detailed description of the operation principles, the fabrication processes, and the operational characteristics of the subsystem will be presented in the full manuscript and in the talk. Figure 1. Architecture of the proposed 40-channel ultra-low-power compact PLC-based ROADM subsystem.

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