Cisco Optics Podcast Ep 55. The smartest data center operators use multi-mode fiber - do you? (4/7)

[00:00:09] Hello everyone and welcome back to the Cisco Optics Podcast where we talk about Plugable Optics for Networks. Multimode Fiber has been the workhorse for fiber optic communication within a data center for years, as well as a choice for Ethernet backbones and office buildings.

[00:00:23] It has a rich history that goes all the way back to the first optical fiber standards when 100 megabits per second was a huge data rate. Anybody remember those days? This is episode 55 and we continue our conversation with Hao Dong, Market Technology Development Manager for Corning's Optical Communications Business.

[00:00:42] We get into power consumption considerations, fiber coupling efficiency, and multimode fiber standards. Hao Dong is a Market Technology Development Manager for Corning's Optical Communications Business. Within this role he focuses on technology and market trends to identify, evaluate, and develop leading optical network solutions

[00:01:01] that form the backbone of today's connected world. Hao has over 18 years of industry experience and has held various positions in engineering, development, and marketing within the fields of optical components, fiber lasers, and optical communications. Hao holds a Bachelor of Science

[00:01:16] in Physics from Wuhan University and a PhD in Physics from the University of Connecticut. And now join me as I talk with Hao Dong. So they're thinking more about the equipment side and if they're comfortable with multimode fiber it's just a very nice comfort zone

[00:01:40] and so even at 400 gig, you know if that's available then yeah that's what they're going to gravitate toward. Right, right. Yeah so especially you know like women we mentioned before right for multimode solution not only we consider it as a lower cost solution but also

[00:02:05] there is a great feature of the lower power consumption and especially nowadays when those data centers they start to deploy you know machine learning AI and those applications it's very, very power hungry right and also they you know for those applications they might

[00:02:29] involves a lot of you know communication functions in there right so end of the day the power is a big concern, power is the lower power consumption of the VIXL of the multimode solution we still

[00:02:46] think it's very much valuable for those applications. That's a great point so the VIXLs are basically lower power than you mentioned the DFB laser do you want to talk

[00:02:54] about that a little bit too? Yes yeah so you know the VIXL I think there is a there is a fix physics behind that why the VIXL consumes the less power if you look at the the lasing threshold right the

[00:03:12] VIXL usually comes with a much lower lasing threshold than the DFB laser so the other thing is you also mentioned this point before right so when it comes to the fiber coupling the multimode

[00:03:27] solution is much, much more efficient when it comes to the VIXL launching light into multimode versus the DFB into a single mode and therefore your you know your your coupling efficiency is high from the power standpoint you know by adopting the multimode you have the better

[00:03:48] chance to utilize your power source so end of the day the multimode you know really offering you the power consumption benefit versus single mode so this is not only true for 100G

[00:04:03] level right for 100G level for example I think we used to do some analysis to quantify the power comparison for 100G transceiver typically it's it's an RZ base right you wouldn't need a CDR,

[00:04:23] a TI as electronics and also of course the power supply the optics so I think typically speaking the VIXL based multimode will deliver around 40% power savings versus a single mode transceiver counterpart so when the speed of migrate to higher speed you know the whole situation is getting a

[00:04:49] little bit trickier because everything is no longer you know an RZ base right everything will migrate to to pan4 so that you have to sort of deploy the very power hungry pan4 DSP yeah right and and from that perspective the the electronic contribute the more the you know

[00:05:13] the percentage of the power contribution from electronics is getting higher but still we will say even though the gap the the power gap between single mode and multimode is shrinking but you know specifically 400G multimode still deliver around 20% power savings

[00:05:32] from the transceiver standpoint versus a single mode so well you know some of the electronics is not necessarily on in the in the optic module like with the 400G QSF-DUD both the FEC and the pan4 modulation it's on the it's it's in the host the switch the

[00:05:53] Cisco switch basically oh yeah so you get a little bit of relief in the module there I'm not sure exactly how much because there definitely is still electronics in the module more so than in the lower speeds right if that's the case you know the the optical

[00:06:11] will play a more important role right from that standpoint that your big so you know power saving feature is more outstanding yeah definitely power is uh is a very big topic these days exactly yeah because especially you know this is a lot of

[00:06:31] the company and the you know organizations really really concentrate on the sustainability perspective right so I think I read an article talking about the you know how power um how power will import how how important the power is for the data center operation

[00:06:58] so roughly speaking I think over 40% of the data center monthly spending uh will be you know either directly or indirectly related to power so eventually the thing is since the power is so critical right since the power is so important it makes sense for data centers to

[00:07:21] kind of like leverage everything they could to lower the power consumption including from the from the transceiver standpoint right if you look at the the whole situation from that way I think we would say the multimode fiber the multimode

[00:07:40] solution it's you know especially valuable right from the economic impact of standpoint from even from the pr value standpoint right uh if you don't mind if we could pivot just a little bit you mentioned organizations that makes me think of standardization organizations um

[00:08:00] you know with multimode fiber uh for people who have worked with it a bit they've probably seen standards called om 3 om 4 there's an om 5 there there used to be om 2 and

[00:08:14] there was an om 1 also wasn't there can you can you explain the history of this where it came from and what what these all mean sure sure um yeah um so um I mean if you look at the the history

[00:08:29] of the multimode fiber um probably we could look at the from the very simple simple way look at the core size um you know history of the core size for the multimode fiber right so uh if you

[00:08:43] trace back to the beginning the very beginning of the multimode fiber was designed with a 62.5 micron core so for those fiber I think it was categorized as om 1 so of course you know

[00:08:59] it's defined by ISO or IC standards you know it's uh it's a 62.5 obviously is bigger than the common multimode fiber core size which is 50 micron nowadays right so that was designed for matching the LDDs light source so of course that's uh even though it's a very low cost

[00:09:22] light source but the problem is that it's a low power and low this is before before VIXOs were around and people would be using LDDs yes this is the before exactly this is before VIXO came around as a workhorse and om 1 actually is

[00:09:39] it was defined um in the mid mid 80s so okay and when did om 2 come around uh om 2 uh I think it came around in the early 90s if I remember correctly so um yeah um

[00:09:57] so om 2 om 3 and om 4 for those fibers they uh also they were defined by ISO, IEC standards and they all have a 50 micron core design right but the problem is that they have a different uh bandwidth or so-called information carrying capabilities um om 2 now

[00:10:20] you know I'm doing more a lot more or less in my opinion is an interim option so today it's nearly obsolete and we we you know typically we don't recommend the om 2

[00:10:32] uh for new new installation as uh anymore um so one of the big reasons is um you know if you look at the like I said the bandwidth right so for speed of the 10g or greater om 2 can only

[00:10:49] support a very short distance so for that reason om 3 and om 4 as a laser optimized multimodal fiber um that was considered as a workhorse for the new installation nowadays so what did they optimize

[00:11:05] so om 2 is for LEDs that was the fourth part of my conversation with how dong next time we'll get into multimode fiber standards we have a new website it's optics.podcastpage.io you can either listen there or use the same podcast platform you've been using all along

[00:11:31] please subscribe better yet leave a review especially if you've been using apple podcast remember we're part of the sysco podcast network where you can find other great sysco podcasts too we also have educational videos on youtube just go to youtube.com and search on sysco optics

[00:11:49] thank you for listening this is pat chow product manager at sysco optics the next episode is part five of my conversation with how dong until next time