3 minute read
Raising the speed limit on the information highway
Optical fibre communication systems are the backbone of the connected world, as virtually all information transmitted over the global communications network is transformed into optical signals that propagate over optical fibres. The Lightwave Systems Research Laboratory (LSRL), located in Walter Light Hall, has more than $10-million worth of advanced test and measurement equipment that enables Dr. John Cartledge, Sci’74, MSc’76, PhD’79, and his research group to conduct innovative, real-world experiments aimed at increasing the bit rate and capacity of optical fibre communication systems to carry information and meet the explosive demand for services anticipated from the emerging Internet of Things.
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“The rising demand for cloud and social media services across the business, educational, health care and entertainment sectors is driving the expansion of the global communications network at dramatic rates of 40 per cent per year. Everybody wants to be more connected, and the ever-increasing demand can be met only by continued innovation in optical communication systems and their enabling technologies,” says Cartledge, Professor and Queen’s Research Chair in the Department of Electrical and Computer Engineering.
A key focus of his research is to help push the per-channel bit rate of optical signals from the 100 gigabits per second provided by current commercial optical communication systems to 400 gigabits per second and one terabit per second. (A gigabit is one billion bits and a
terabit is one trillion bits, representing the amount of data transmitted per second in a telecommunication system.) “Going four and ten times faster is more challenging. We’re exploring and testing techniques for transmitting high bit-rate signals over optical fibres and mitigating the degradation in the quality of the optical signal that occurs because of the high bit rate and long distances,” Cartledge explains.
Equipment/features list:
Four-channel arbitrary waveform generators Binary pulse generators and error performance analyzers High bit rate optical transmitters Direct detection and coherent receivers Equivalent-time and real-time sampling oscilloscopes Optical sampling oscilloscope Lightwave component analyzers Lightwave signal analyzers Optical spectrum analyzers and a high resolution spectrometer
The cutting-edge facility is equipped with arbitrary waveform generators, binary pulse generators, optical transmitters, coherent receivers and realtime sampling oscilloscopes that enable the researchers to do experiments that push the transmission limits of optical communication systems, observe the effects and test solutions, such as preand post-compensation techniques for the signal distortion that occurs during propagation over a fibre.
“This lab is distinguished from many others in the world because of the extraordinary capabilities of the equipment. With this equipment, we can generate advanced modulated optical signals that have the potential to provide higher capacity for optical communication systems. The lab’s capabilities have allowed us to become a major player on the world scene in this field and collaborate with companies that make optical fibre communication Measuring dual polarization optical signals using an optical modulation analyzer.
systems and the requisite components/ devices, such as Ciena and Finisar,” says Cartledge, who has received generous support from the Canada Foundation for Innovation for the lab’s infrastructure.
Students have the opportunity to do real experiments—in addition to their simulations—that push the envelope of optical communications technology and prepare them to develop the next generation of products and systems for the connected world once they graduate. “Graduate students and post-docs are able to develop advanced experimental skills that are very useful when they go to industry. They are in a position to very effectively help companies build and develop new optical communication products because of the research they’ve done here,” Cartledge says.
As a research engineer, Cartledge has established a facility geared toward assessing the performance of highbit-rate optical fibre communication systems. “I enjoy the challenge of doing experiments that test one’s ingenuity. I like to demonstrate that proposed ideas provide a meaningful advance and result in improved performance,” he says.
Measuring the frequency response of a directly modulated laser using a four port lightwave component analyzer.
