What Is The Future Development of ROADM?

As data traffic continues to surge, network operators must adapt their infrastructure to meet growing demands while reducing costs. Reconfigurable Optical Add-Drop Multiplexers (ROADMs) are at the forefront of this evolution, offering enhanced performance, flexibility, and efficiency. This article explores the future development of ROADM technology, highlighting seven key areas of advancement that promise to revolutionize optical networking.

Enhanced Coherent Transceiver Wavelength Reach

ROADM technology is advancing to maximize the capacity and reach of coherent transceiver wavelengths while minimizing costs, power consumption, and physical space. With the introduction of flexible-grid ROADMs featuring 12.5 GHz and 6.25 GHz granularity, along with gridless/colorless add/drop and wide-passband fixed filters, higher baud rates are now possible. Enhanced ROADM cascadeability, improved amplifier performance, and automated generalized optical signal-to-noise ratio (GOSNR)-based link control further boosts efficiency. Dynamic gain equalization (DGE) optimizes wavelength power in in-line amplifiers (ILAs), allowing ROADMs to support more wavelengths and higher data rates over longer distances.

More Add/Drop and Degree Flexibility

ROADMs now offer greater flexibility in both add/drop functionality and the number of degrees. The evolution to colorless-directionless (CD) configurations with MxN WSSs and colorless-directionless-contentionless (CDC) setups with multicast switches (MCSs) and MxN WSSs provides various options for cost and scalability. High-baud-rate fixed add/drop and WSS port counts of 30+, 48, and even 60 ports support large hub sites and parallel fiber links, enhancing CD and CDC add/drop scalability. This flexibility allows network operators to efficiently manage and reconfigure optical channels, improving the agility and responsiveness of their networks.

Compact Size

The physical size of ROADMs has significantly decreased due to advancements in WSSs and amplifiers, the integration of SFP pluggables, and the development of twin and quad WSSs on a single unit. Compact modular platforms now deliver two ROADM degrees in 1RU, with even denser configurations on the horizon. This reduction in footprint not only saves physical space but also reduces power consumption and cooling requirements, contributing to lower operational expenses (OPEX). The compact size of modern ROADMs makes them suitable for deployment in various environments, including data centers, central offices, and edge locations.

Enhanced Operations and Manageability

Innovations addressing operational costs and manageability include multi-haul compact modular platforms, zero-touch provisioning, cabling verification, auto-discovery of transponder/muxponder and router modules, and switchable gain amplifiers. High-performance link control simplifies planning and configuration. Coherent probes enable wavelength path validation before transceivers are installed. Other enhancements include streaming telemetry, high-resolution coherent OCMs , and integrated optical time-domain reflectometry (OTDR), including coherent OTDR. These advancements streamline network operations, reduce human errors, and improve overall network reliability and performance.

Higher Network Availability

Optical restoration times are improving from minutes to seconds with faster power balancing enabled by enhanced link control. Integrated OTDR allows for quick localization of fiber cuts, with coherent OTDR extending this capability to long repeatered submarine fibers, potentially providing advance warning of terrestrial fiber cuts. Amplified spontaneous emission (ASE) noise sources enhance the resilience of C+L networks, enabling faster recovery after failures. Cable verification can significantly reduce cabling errors. In protected ring and mesh scenarios requiring full degree separation, compact modular and ROADM-on-a-blade configurations reduce the footprint penalty for placing each ROADM degree on its own shelf. Node-on-a-blade increases network availability in unprotected linear chain scenarios by reducing the number of components at each intermediate node, thus reducing the risk of service-impacting component failure.

Increased Openness

ROADMs are becoming more open, with integrated optical channel monitors, WSS-based attenuation, and alien wavelength-friendly link control simplifying the support for third-party wavelengths. Flexible-grid capabilities also pave the way for spectrum services. Management interfaces have transitioned to open APIs (NETCONF, RESTCONF, gRPC, gNMI) with Open ROADM and future OpenConfig, YANG data models. The Open ROADM MSA provides standards for line interoperability between CD metro ROADMs from different vendors. This openness fosters a competitive and collaborative ecosystem, driving innovation and reducing costs.

FS ROADM Introduction

FS D7000 series ROADM-09T is based on advanced next-generation wavelength-selective switch (WSS) technology to support full colorless, directionless, and contentionless (CDC-F) system configuration. This module is a built-in pre-amplifier and booster amplifier which can simplify the installation and scalability of your ROADM network while improving its overall flexibility and performance. ROADM-09T supports N*12.5GHz flexible grid (4≤N≤12). Besides, this module can achieve add-and-drop services or pass-through.

Figure1. FS ROADM

Conclusion

In conclusion, driven by the requirements of coherent evolution and the trend toward open optical networking, ROADM technology continues to evolve along these seven vectors that are collectively enabling significant reductions in optical network total cost of ownership. The future of ROADM technology is promising, with ongoing advancements poised to meet the ever-increasing demands of modern optical networks.