Spring 2018 Optical Connections Magazine



A s networks evolve to meet the growing demand for higher bandwidths to support an ever-increasing range of services, the tools to test and measure those networks have to evolve too. The move from 100G to 400G to support functions like HDTV, financial trading and mobile backhaul along with the demand for low latency doesn’t just present challenges for fibre and component manufacturers and network installers, but for the test and measurement sector too. Thorough testing of equipment and services before and after deployment is a vital part of ensuring reliability and performance of networks and is nothing new, but as bit rates increase beyond 100Gbps the world of test and measurement becomes increasingly complex – and expensive. “The first question of test and measurement is very much the physical,” says Dr Paul Brooks, Strategic Director, Lab & Production at Viavi Solutions. “Can we actually build these things? Is there enough margin?” That basically means two questions, he says. “Can I build it, and can I make it reliable?” ONGOING CHALLENGES Test and measurement challenges range from the ongoing stumbling blocks to those that come as a result from the drive for higher bitrates, says Caroline Connolly, CEO of OptoTest. “Higher data rates mean reduced dynamic range, which leads to reduced loss budget and connectors and cable assemblies that require more precision. When a connector is specified with less than 0.1dB of loss, that connector must

Developments such as 400G are bringing the need for specialist test and measurement tools for both networks and devices. Ellen Manning investigates.

they can meet the requirements of the network. This means being able to withstand the environmental shifts that will take place over the life span of the network and the equipment needs to be very stable over long periods of time (typically one to four weeks).” Equipment for product development has to be “feature rich with the tightest tolerances possible”, says Connolly, while the development phase sees customers want to try out dierent scenarios, requiring flexible equipment. Once components have been verified and move to production, the emphasis shifts to the need for speed as well as accuracy. “This means that the equipment still needs to meet a similar level of accuracy and precision as the R&D equipment, but it must be extremely user friendly and fast to minimise production costs. OptoTest has configured our systems so that they can be used in both the R&D and production environment. We have developed software suits that have all the bells and whistles required for the litany of qualification tests during R&D and software suits that are simple to configure for an ecient production line.” 400G CHALLENGES Alongside the ongoing challenges when it comes to test and measurement, 400G brings a whole new list of obstacles. “As

be tested with a light source and power meter with at least 0.01dB of precision and accuracy. These incremental changes keep us (test and measurement companies) on our toes and working to improve.” Of course, says Connolly, there are the “lifelong most basic challenges”, including dirt and contamination. OptoTest is dedicated to informing and training its customers to improve their test and measurement process, adds Connolly. “Our equipment helps those manufacturers to ensure the losses in their systems meet the strict requirements of the end user. We have equipment for production environments and also specialised equipment for the R&D departments to help them qualify their components for environmental conditions like temperature or even torsion to ensure throughput in extreme environments.” TESTING VARIES Unsurprisingly, testing varies between product development and during live network operations. “These are very dierent types of tests with dierent requirements; however, the component performance is critical in all aspects along the development to installation spectrum,” says Connolly. “During the development phase the components need to be verified that


| ISSUE 12 | Q1 2018


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