[00:00:12] Hello everyone and welcome back to the Cisco Optics Podcast where we talk about pluggable optics for networks. In the pluggable optics industry, every next generation is led by countless presentations and proposals at standards bodies meetings along with lots of lab development and testing behind the scenes. Right now, the industry has its sights set on 3.2 terabit transceivers with 400 gigabit per electrical lane. All those meetings and all that testing are happening as we speak.
[00:00:39] Today, I am joined by John Calvin, Strategic Planner and Datacom Technology Lead at Keysight. John has been bridging the measurement science gaps of emerging telecom and datacom development efforts for 20 years. He has chaired multiple physical layer interoperability working groups and is currently serving as contributing member to IEEE 802.3, OIF-CEI, InfiniBand, and PCIE development efforts.
[00:01:04] John holds a BSEE from Washington State University, and his graduate-level studies are in signal processing from Stanford University. In Episode 68, we continue our conversation with John. We get into the limits of copper and emerging alternatives such as plastic waveguides and hollow core fiber. And now join me as I talk with John Calvin.
[00:01:35] John Calvin, Chief of the United States, Chief of the United States, and the United States, of the United States, of the United States, of the United States. You could tow a truck with a copper cable, and it's still plugged in your data center, and it'll work just fine. You could slam the door on your copper cable. It's going to work just fine. The reliability of copper cable, especially passive copper, is just stunningly good. It doesn't wear out. It doesn't break. And that's one of the reasons why copper is still in the game.
[00:02:02] It's, I mean, as we go to higher data rates, is there a point where copper just throws up its hands and says, okay, I can't do a meter anymore? God, you know, I used to keep a data sheet. It was an article from a test tool. And many years ago when I worked at a different test and measurement company, we had a data sheet.
[00:02:28] And it talks about the old ISO bus interface, right? And it says, you know, as speeds begin to approach, the blistering performance of 100 megahertz buses. And, you know, back then that was 33 megabits per second. That was, you know, in 1995. That was really, that was cutting-edge stuff back then. Oh, ISO buses and ESA buses, predating PCI Express.
[00:02:57] And the idea was copper was a tool of choice, but you'd eventually run out of gas. And the reality is they're finding ways to reduce the surface roughness on copper. This is one of the things that makes copper less effective. They chemically dip copper to make the surface smoother so it's better for transmission of signals.
[00:03:18] And to be honest with you, I believe there is still untapped market out there in transmission physics and transmission systems that may not be copper-based at all. We're starting to see, there's a couple companies out there right now that have small plastic waveguides. They have mylar-coated plastic film waveguides. They're plastic, right? And they just pump energy into these things with a carrier.
[00:03:48] And they behave like a copper cable, but they're made out of plastic. Wait, so they're non-conductive because they're plastic? Non-conductive, yeah. And so what are they carrying? It's not optical? It's not optical. It's a 100 gigahertz carrier that gets punched through this waveguide. And the waveguide is, you know, the size of the tip of a pencil. So it's a dielectric waveguide then? It's an air dielectric waveguide.
[00:04:16] So it's a little square tube and it's got mylar on it to give it a good reflector boundary condition. And you can shoot microwaves through these things like no one's business. So, I mean, that's an example of some of the advances that you're seeing in this space and how some novel designs are really advancing the state of the art. And the benefit there, again, is you don't need to go to an OD converter. You don't need to go through, have the latency of optics.
[00:04:47] It's passive. And it's all passive. The key is that it's passive, right? Well, in this case here, this particular case I was describing is active. But the point is, is that you get to do it without the complexity of having an optical waveguide in your setup.
[00:05:05] But I, I think that when I walk past the McGill University back and forth when I go to the IEEE session here, McGill has been a great place for some of the more cutting edge design principles here in around transmission physics. And whether it's waveguide based or single mode fiber based or multi-mode fiber based as a whole, right now you see optics in the hollow core space taking off.
[00:05:34] It turns out that similar idea to the, the air core dielectric. If you take a fiber and you have hollow core, uh, it's actually transmission is faster. It goes faster through air than it does through, uh, through quartz. And you can actually shave off, uh, some of the precious latency issues that people have and make the transmission faster.
[00:05:59] So we're going to see, I think, an explosion of, uh, different novel ways to do signal transmission. I'm hoping that pretty soon we're going to see some high temperature superconductors in this space. And you can imagine if right now we, we crack the nut and make this work with 45, 50 DB channels, which is what we'll likely see at, uh, 400 gigabits per second.
[00:06:22] Uh, if we're able to build better waveguides and, and shorten these connections, we'll have the advantage of going to, you know, 1.8 nanometer, two nanometer designs with these advanced equalizers on both sides. And then we'll have lower loss cables in between. And that technology, I think is going to sit really, really well. The, uh, you mentioned, uh, McGill University and, you know, transmission lines and physics.
[00:06:52] Do you have visibility to like the younger generations and what they get educated in? Um, are they, is there a curriculum in this type of thing still? Because when I, by the time I got to grad school in the late nineties, I had learned that the undergraduate curriculum, uh, had evolved such that you could get away with getting an EE degree without taking electrostatics or electrodynamics.
[00:07:20] And I was blown away because at that time all the focus was on, you know, signal processing, information, technology, computer science. And that's just the way the wind, the way, the way the wind was blowing at that time. And I'm, I haven't kept up and I'm just wondering, has anything reversed back towards, you know, physical sciences? To be honest with you, physical science is still the hardest aspect of the engineering discipline right now.
[00:07:49] And it's the one thing that people are more eager to give up if they have to give something up because, to be honest with you, you know, uh, the, uh, fields and waves is tough. It's hard. Yeah. It's, it's really tough. And, and increasingly that's exactly the skillset that you need to be able to build these transmission systems in order to be effective, whether it's a copper wave guide or a fiber, you need to understand the transmission physics.
[00:08:15] Well, that's being taught in fewer and fewer places, but you know, um, I know the, uh, the graduate program at McGill, they've actually been, uh, uh, responsible for some of the high watermarks here in single lane bit rates. In fact, I think they, they currently sit on the highest speed ever, uh, transmitted over a single pair copper. Um, if I'm not mistaken, it's somewhere in the 650 gigabits per second space.
[00:08:44] And they've, they have engineers that have, um, are on the cutting edge and far enough out ahead of the instrumentation capability. And they've built some instruments or modified instruments that allow them to, to demonstrate these extraordinary speeds. So the research is going on. The people are doing this at graduate level as for undergraduate. Yeah. It's hard to say anymore, but, um, I'm convinced these sorts of things work on a pendulum basis.
[00:09:11] And I believe that, uh, you're going to see people coming back into the space because to be honest, people like us are retiring and, um, we're not being backfilled to people who have fields and waves experience. I mean, personally, I think it's a shame, but like you said, yeah, it tends to be like the heart, one of the harder classes in the curriculum. And, uh, for most people, I mean, some people just gobble it up and they're just naturals, but a lot of people struggle. Yeah.
[00:09:40] I, uh, everyone struggles in fields and waves myself included. So, I mean, it's a, it's a Rubicon. Everybody has to get over at some point if you could be electrical engineer. Yeah. You mentioned testing an instrument. I mean, that's, that's, that's where you live. Right. And I always wondered, uh, your perspective must be incredibly unique because you, you have to be at the forefront, right? Because everyone is developing the next generation. They need equipment.
[00:10:10] Yeah. To test what they're working on, right? So how do you, how do you stay ahead of that curve? And like, what, what is it like? Well, you know, to be honest with you, our customers are, are pretty instrumental in telling us, um, what we need to be focused on. Um, you know, we, we just rolled out publicly our, our 250 gigahertz vector network analyzer.
[00:10:35] So if you want to be able to look at a backplane or a channel out to 250 gigahertz, um, think about it. Um, everything we've done in our career, everything I've done in my career has been at 90 gigahertz or less to the left of the 90 gigahertz mark. And now all of a sudden you got 90 gigahertz is a third of the way downfield. And you have this empty field out there in performance.
[00:11:01] People are going to start learning about dielectric properties, nonlinear properties of, of different materials out in the 150 and the 200 gigahertz region, 220 gigahertz region. And these tools open up that design field. So you have clever engineers and you have tools now that can show you what you're designing to. You can see the problem. You can fix anything if you can see the problem.
[00:11:30] And, uh, it's going to be, um, like I was saying earlier about the people who are going to move to five terabits per second is people who understand signal transmission in the hundred plus gigahertz region, which is. Now our generation is going to be the next generation of design engineer that are going to make those huge advancements and be at five terabits per second before we know it. Um, but the, uh, you know, we have our, our, our marching orders. I'm a, I'm a planner at Keysight.
[00:11:58] So my role is basically to make sure that our instrument portfolio is lined up ahead of the industry that we're serving. And again, this is my, my industry is quite narrow. It's the ethernet industry or the high speed networking industry. And so we're focused on making sure that the VNAs, and that's typically what we lead with. Cause if you're going to. Sorry, what is VNA? Oh, a vector and network analyzer. Oh, sorry. Okay. Yeah. That's a short term of a VNA.
[00:12:26] And you know, a VNA is what you use to characterize a copper channel or even optical interconnect. You can use it to characterize anything. It's just going to sweep a tone across starting at 10 kilohertz and ending at 250 gigahertz. And it measures the amount of transmit energy and reflected energy. And, uh, it allows you to extract the scattering parameters or the S parameters of a cable or optical assembly or things like that.
[00:12:54] So it's, it's one of the fundamental tools that's used to characterize the, uh, core components of a network. So you said the customer is involved in the process. Does that mean that customers said like, Hey, we need a 250 gigahertz VNA? Yeah. And then you just had to go figure it out or were they, were they, was there any collaboration?
[00:13:31] That was the fifth part of my conversation with John Calvin. Next time we'll get into the measurement science and precision instruments needed to characterize signals at femtosecond timescales. Please follow the Cisco Podcast Network on Spotify or Apple Podcasts. Better yet, leave a review on Apple Podcasts. Remember, you're listening to the Cisco Optics Podcast, which is part of the Cisco Podcast Network, where you can find other great Cisco podcasts too.
[00:13:58] If you want to listen to us on a website, go to optics.podcastpage.io. We also have educational videos on YouTube. Just go to youtube.com and search on Cisco Optics. Thank you for listening. This is Pat Chow, director of technical marketing engineering at Cisco Optics. The next episode is part six of my conversation with John Calvin. See you there.