How a Fiber Laser Works

Ғылым және технология

How a Fiber Laser Works - a short introduction into the science of light, optical fibers and the development of optical fiber lasers.

Пікірлер: 204

  • @Heatseeker1
    @Heatseeker13 жыл бұрын

    after 60 seconds: Hi I'm a cartoon photon with arms, here to tell you that wavelength (denoted lambda) refers to the colour of light After 7:43: multiple fibres can feed into or split out of one evanescant field leading to the devepment of a fused biconic coupler ...Well, that escalated quickly.

  • @ibraheemkhan9773
    @ibraheemkhan97737 жыл бұрын

    *watches video* "A short introduction" 2 minutes later *12 wikipedia tabs open*

  • @tor9885

    @tor9885

    6 жыл бұрын

    хе-хе

  • @pike727

    @pike727

    6 жыл бұрын

    I do that all the time.

  • @omsingharjit

    @omsingharjit

    3 жыл бұрын

    But wiki on this topic doesn't exist

  • @cplcabs

    @cplcabs

    2 жыл бұрын

    Wikipedia? Oh dear

  • @bryanst.martin7134

    @bryanst.martin7134

    2 жыл бұрын

    @@cplcabs Wikidpedia Like AOC, occasionally right.

  • @92kosta
    @92kosta5 жыл бұрын

    I am a fiber laser operator and I still don't know how it works. All I know is that magic comes through the nozzle which in turn cuts through steel.

  • @jewwyjones9760

    @jewwyjones9760

    5 жыл бұрын

    I run a waterjet and my boss has a pricey fiber laser on the way. This video scares me a bit damn all that math

  • @Stefano_Rodriguez

    @Stefano_Rodriguez

    4 жыл бұрын

    @@jewwyjones9760 I operate an Amada Fiber laser. It's easy to operate, don't worry.

  • @jewwyjones9760

    @jewwyjones9760

    4 жыл бұрын

    @@Stefano_Rodriguez well my boss opted for a "cheap" laser. Vyteck with laserworx. I've moved away from the fabrication stuff now I'm a machine operator otw to programmer. They've had soooo much trouble with this laser. Can't seem to dial in anything thicker than .188 inch (7 gauge) stainless. The gas doesn't stop bw cuts lol Vytek said 🤷‍♂️.

  • @Stefano_Rodriguez

    @Stefano_Rodriguez

    4 жыл бұрын

    @@jewwyjones9760 I see. Programming is good! I do the programming/nesting for the Amada as well. Maybe, they just need to play with the settings properly. I cut 3/8 stainless steel with the Amada with no problem, but we just need adjust the settings a little to get our smooth cut.

  • @rupamrakshit7825

    @rupamrakshit7825

    4 жыл бұрын

    Hi ,, I am pursuing MTech from Laser Science and engineering from India and I want to work in foreign countries ,, friends as you are in laser related field ,,I want your favour ,,

  • @appa609
    @appa6093 жыл бұрын

    This is much higher quality than I expected

  • @wmffmw1854
    @wmffmw185411 ай бұрын

    Excellent Presentation. I watched first hand the development of a Fiber Laser used in LIDAR Applications from the perspective of a PCB Layout Engineer dealing with Pump Diodes and Optical Racetracks and the electronics driving them. Made for some interesting challenges. I never expected to have to change a board layout because of the reflectivity of objects such as a Stop Sign at the frequency of our Laser. Now I have a much better appreciation for the issues facing the scientists and the problems we Engineers had to solve to create a low cost mass manufacturable device. Thanks! We succeeded by the way.

  • @yachalupson
    @yachalupson5 жыл бұрын

    A bit to take in there! Thanks for taking the time to present this fantastic introduction to fibre technology.

  • @leegenix
    @leegenix7 жыл бұрын

    I thought the fibers optically transmitted the laser light from a laser diode. I had no idea this kind of technology existed til now. Amazing.

  • @kamariahrajainthiran1805

    @kamariahrajainthiran1805

    9 күн бұрын

    ✍️👍Simple & easy

  • @notamouse5630
    @notamouse56305 жыл бұрын

    Thank you for the explanation of how fiber coupling works I haven't found such useful details elsewhere.

  • @rasberryjam2178
    @rasberryjam21789 жыл бұрын

    That was intense but also amazing. A lot of those terms were over my head but that was well done even though it is a very complex subject. Would be awesome to see a multi-video series on this subject. Very cool stuff.

  • @stevenfirst8222
    @stevenfirst82226 жыл бұрын

    I love, love, love this level of explanation. This video is one of the best education photonics videos I have seen ever.

  • @DimensionMachine
    @DimensionMachine5 жыл бұрын

    The most relatable explanation I have seen so far. Thanks!

  • @hf2164
    @hf21646 жыл бұрын

    An excellent informative presentation, thank you.

  • @ikeimage
    @ikeimage7 жыл бұрын

    Yes a very short basic intro into fiber lasing

  • @KamranQaderi
    @KamranQaderi7 жыл бұрын

    Amazing intro on Fiber LASERs. Thanks!

  • @robinseifert218
    @robinseifert2185 жыл бұрын

    Priceless...Thank You!

  • @drjswizzle8235
    @drjswizzle82353 жыл бұрын

    Fantastic video and explanations. Thank you , even years after you made it, still very helpful. WTG!

  • @fytubevw
    @fytubevw2 жыл бұрын

    Both clear and very informative. This was useful!

  • @lawrencerodeback
    @lawrencerodeback2 жыл бұрын

    It's an easy explanation to follow if you replace all the formally unknown words with "things" and "stuff" and glaze over the other information he may have given.

  • @stevejackson2941
    @stevejackson29418 жыл бұрын

    Thank you very much for sharing this knowledge with me. You are truly a gentleman and a scholar.

  • @FilterYT
    @FilterYT4 жыл бұрын

    Thanks for the amazing explanation.

  • @monjurulalam5761
    @monjurulalam57612 жыл бұрын

    You gave an excellent description.We learned a lot about fiber lasers. 👍💐

  • @markus1000000001
    @markus1000000001 Жыл бұрын

    Excellent and detailed explanation. The issue that I am involved in is looking for the best temperature for the best wavelength so that the pump diodes bring the least pressure. The challenge is the temperature of the pumps and the temperature of the oxygen and nitrogen during cutting. By bringing the pump temperature to minus 12 degrees, we obtained lower quality and energy

  • @jenandtedreutzel8112
    @jenandtedreutzel81128 жыл бұрын

    Really excellent introduction. Well done and Thanks!

  • @CatherineSuperwaveLaser
    @CatherineSuperwaveLaser8 жыл бұрын

    Nice explanation, thanks.

  • @kenmason6135
    @kenmason61355 жыл бұрын

    Nice video, one question, what's the wall to aperture efficiency?

  • @scythe1092
    @scythe10923 жыл бұрын

    This is the perfect kind of summary that should be done before most of engineering (and other fields) courses, and after this, the detailed explanations would make sense for the first time.

  • @PineappleQuesadillas
    @PineappleQuesadillas5 жыл бұрын

    One of the best videos on youtube, period. Keep it up.

  • @saskiavanhoutert6081
    @saskiavanhoutert60812 ай бұрын

    Excellent Presentation. Thanks. CPU's can be made round with glassfibercables perhaps and a lasergun or ledgun at the beginningpoint.

  • @ErikaSilva-kz1qn
    @ErikaSilva-kz1qn4 жыл бұрын

    Thanks!! I really appreciate your efforts in this representation, it helps me to learn technical English and fiber optic principles (my native language is Spanish)

  • @omsingharjit

    @omsingharjit

    3 жыл бұрын

    😂😂 vise versa My technical english is good but non-technical is bad

  • @anthonyvolkman2338
    @anthonyvolkman23389 жыл бұрын

    This was extremely helpful, thank you

  • @seriousCADninja
    @seriousCADninja6 жыл бұрын

    Amazing video! Thanks!

  • @henryhartsfield4574
    @henryhartsfield45744 жыл бұрын

    I have been Edumacated!!! Thank you for opening my eyes to this technology!!!! 😳

  • @kevinbower7142
    @kevinbower71428 жыл бұрын

    yes amazing analysis and description

  • @omsingharjit
    @omsingharjit3 жыл бұрын

    But if this type of laser needs laser diode to pump it , then why we need fiber after that at all ? I mean in other laser like ruby , hene we pump it with normal diffused light from dis lamp that that active medium makes laser beam from light but in this laser if we use , let's say 1 watt Laser diode of any wavelength so how it would be beneficial to use fiber as amplifier medium because due to the fact that efficiency can't go higher then 100 (according to energy violation law) ?

  • @jasonkocher3513

    @jasonkocher3513

    2 жыл бұрын

    I'm going to take a stab at answering this... because I have struggled with the same question. I think the goal is to get the beam quality to single mode and smoothly Gaussian intensity so the energy can be maximized when focused into a tiny dot. So the better the beam quality, the smaller the dot you can focus, the higher the Watt per Square Centimeter. Taken to its logical limit... the single mode with best beam quality has the smallest focal point which yields the highest intensity. Can anyone else validate this answer in case I'm missing something too?

  • @avixs1543

    @avixs1543

    Жыл бұрын

    @@jasonkocher3513 Yeah its a massive pain to combine the ouput of multiple diodes soo this basically solves that problem without needing a bunch of lenses to combind the ouput perfectly.

  • @Hyperian
    @Hyperian8 жыл бұрын

    pumping, strippers, and doping? this sounds like an investment to me!

  • @lukeryktarsyk1234

    @lukeryktarsyk1234

    8 жыл бұрын

    High yield indeed.

  • @MrDubs

    @MrDubs

    6 жыл бұрын

    Only interested in the pump end of the cavity.

  • @deletingthis00

    @deletingthis00

    3 жыл бұрын

    Hi. Have you come to worship the shrike?

  • @henmich

    @henmich

    3 жыл бұрын

    That's why you need one of your strippers to catch the residual pump... It's okay, it's released as heat... lol

  • @bryanst.martin7134

    @bryanst.martin7134

    2 жыл бұрын

    @@deletingthis00 Who are you to take His name?

  • @tusharpawar1
    @tusharpawar12 жыл бұрын

    awesome high quality material

  • @jaferaa
    @jaferaa5 жыл бұрын

    Excellent vedio very useful thanks bro

  • @Hellohallo
    @Hellohallo3 жыл бұрын

    my "scientific neurons" are happy again. education like this, gives me a sence of what i truly enjoy. the future is going to be exciting. too be honest though, i found this after seeing a ship being fitted, and northop grumman talking about theire use of fibre optic lasers.

  • @dolphin.cheddar
    @dolphin.cheddar5 жыл бұрын

    This is awesome

  • @RAMACHANDRANSIR
    @RAMACHANDRANSIR3 жыл бұрын

    Excellent presentation

  • @vikrantvijit1436
    @vikrantvijit14362 жыл бұрын

    Thanks for informative Quality content.

  • @humanworlwide830
    @humanworlwide8306 жыл бұрын

    Very impressive n a big thumbs up.. cleard lots of concepts now .. keep it up ☺

  • @metebas3400
    @metebas34003 жыл бұрын

    Holy hell, amazing explanation.

  • @witcherdxtlaser3292
    @witcherdxtlaser32923 жыл бұрын

    professional explanation

  • @ManojKumar-ej4jd
    @ManojKumar-ej4jd Жыл бұрын

    Thanks for amazing explain

  • @philiprogers5772
    @philiprogers57722 жыл бұрын

    Loved it.

  • @sungboklee6790
    @sungboklee67906 жыл бұрын

    Amazing. I just wish I could understand half of this video though

  • @user-xd7zk1pw5y
    @user-xd7zk1pw5y13 күн бұрын

    Great video

  • @calebsullivan3955
    @calebsullivan3955 Жыл бұрын

    Okay but can we talk about how good the music in the beginning was holy shit

  • @Zenodilodon
    @Zenodilodon5 жыл бұрын

    This was very informative, but I want to know if you can collimate a fiber laser into a low divergence beam. As a laserist this was very enjoyable, I work with ILDA show lasers and have wondered about the use of fiber coupled lasers. I know that you can collimate after a resonator but what about raw fiber output?

  • @omsingharjit

    @omsingharjit

    3 жыл бұрын

    Nice to see u here 😂

  • @Zenodilodon

    @Zenodilodon

    3 жыл бұрын

    @@omsingharjit Indeed. I also answered my own question since then which is " Yes " lol

  • @omsingharjit

    @omsingharjit

    3 жыл бұрын

    @@Zenodilodon it's obvious because of curiosity and time . 😁🤓

  • @pokeytheturtle6449
    @pokeytheturtle64494 жыл бұрын

    Thank you sir for this video

  • @julianmojica3513
    @julianmojica35139 жыл бұрын

    great job.

  • @lalalalalisa337
    @lalalalalisa3373 жыл бұрын

    how many hours to use this machine

  • @CalvinCai_Frisbee
    @CalvinCai_Frisbee6 жыл бұрын

    there is so much to learn

  • @duelistknight
    @duelistknight5 жыл бұрын

    Does anyone know what will happen when a fused biconic opto-coupler have same output diameter as both inputs????

  • @PetesShredder
    @PetesShredder7 жыл бұрын

    I just got a fibre laser machine for engraving. Amazing to think that this is going on inside it when I use it...

  • @fraire711
    @fraire7112 жыл бұрын

    I work with two 4,000 watt, and didn’t know what was going on inside. This video helps out. They are fiber lasers. I’m always amazed of what you can cut.

  • @ammaryassir1980

    @ammaryassir1980

    7 ай бұрын

    And here I was thinking a 100 watt laser was powerful hahahaha

  • @slserenader

    @slserenader

    3 ай бұрын

    lol i work on a 24,000 watt laser, I can pierce through 1.5 inch steel in less than a second@@ammaryassir1980

  • @videakias3000
    @videakias30004 жыл бұрын

    does the resonator have any other names? i can't find any info about it anywhere.

  • @cambridgemart2075

    @cambridgemart2075

    3 жыл бұрын

    Try looking for cavity or resonant cavity

  • @objuan6
    @objuan64 жыл бұрын

    Most excellent brain food. Bravo!

  • @agredo
    @agredo8 жыл бұрын

    great video

  • @ericwilliams2122
    @ericwilliams21225 жыл бұрын

    superb tutoril

  • @sayftaleb6020
    @sayftaleb60207 жыл бұрын

    nice where can i get the reference of this research?

  • @bendriscoll6631

    @bendriscoll6631

    5 жыл бұрын

    Do you know about ResearchGate or Web of Science? You may need to be enrolled in a university to access them.

  • @whatevaneva
    @whatevaneva Жыл бұрын

    What is unpumped self-lazing @6:48?

  • @tombouie
    @tombouie7 ай бұрын

    Well-Done

  • @kssrao7102
    @kssrao71022 жыл бұрын

    good illustration

  • @ksanalyticalsystems2438
    @ksanalyticalsystems24383 жыл бұрын

    Excellent information. I was a little worried with it started with an animated photon, but I'm impressed that the core information was not simplified beyond reason. Of course, I'm a guy who has Bragg's Law tattooed on my arm.

  • @alfonsocanales7210
    @alfonsocanales72105 жыл бұрын

    what kind of material can we cut using Fiber laser??? can we cut silicon??? thanks

  • @chanxanlaserequipment4006

    @chanxanlaserequipment4006

    5 жыл бұрын

    Fiber laser cutting machine is specially used cutting stainless steel,carbon steel and coper and other metal We often use co2 laser cutting machine for silicon WhatsApp/Wechat me : +86 18361445350 for more details Web: lasermachinery.en.alibaba.com/ www.szchanxan.com

  • @kryptokrow
    @kryptokrow2 жыл бұрын

    wow i didnt know all this was leading to engraving and other streams of art and income. thanx. i was really hoping you could recommend a portable unit for rust and paint removal on cars as rust repair is the most time and money consuming. seen a portable unit by Questt

  • @ehsandaneshvar
    @ehsandaneshvar5 жыл бұрын

    thanku

  • @jewwyjones9760
    @jewwyjones97605 жыл бұрын

    Raman scattering and fiber will certainly increase a core size whoa!

  • @drspastic

    @drspastic

    4 жыл бұрын

    I experienced ramen scattering because of ripped packet loss. They were beef flavour

  • @cy3486
    @cy34864 жыл бұрын

    nice video ! could i reprint this video to bilibili? all information would be reprint as well.

  • @mohitpatil7686
    @mohitpatil768610 жыл бұрын

    Good Explanation (y)

  • @matthewkleinmann
    @matthewkleinmann6 жыл бұрын

    Interesting video. I have a few Q's if you don't mind. 1) You keep stating that you (the industry?) is striving for single mode fiber. I thought the communication industry liked multi mode fiber because they can run multiple wavelengths down it at the same time and get more bandwidth out of the same fiber. Perhaps for the purpose of fiber lasers single mode fiber is desired over multimode, 2) I am not sure of the gain of the fiber laser. If I am seeing this correctly, you need to start with a laser to make the fiber laser work. I thought semiconductor lasers were already monochromatic and I can not see getting more power out than you are putting in or you would have perpetual motion. What exactly are you gaining? Is this a way of shifting to a new wavelength? 3) Perhaps more of a statement.. The one big thing I do see is how to parallel multiple lasers together, but that seemed to have little to do with the fiber laser part. Is that a correct assumption? I plan on watching this again. It is definitely interesting. Thank you and your company for presenting it!

  • @DehimVerveen

    @DehimVerveen

    5 жыл бұрын

    After reading Wikipedia, this is what I think I understood: 1) The communication industry also likes single mode fibers. Multi mode means that light takes multiple different paths through the fiber. One path is longer than the other. This means light will take longer to traverse a longer path than it will take to traverse a shorter path. This is modal dispersion. for example a pulse with a length of 1 ns is fired through a fiber. Lets say the slowest mode takes 100 ns to reach the other end, whereas the fastes mode take 90 ns to reach the end. This means a 1 ns pulse at the input of the fiber has turned into a 10 ns pulse at the output. This decreases the signal bandwidth of the fiber. furthermore single mode fibers are less lossy. 2) The fiber laser allows you to take one or more high numerical aperture lasers and combine them into one high power low numerical aperture single mode laser. The pumping beam travels mostly through the inner cladding, but interacts with the core to pump the lower energy state electrons into a higher energy state. when these electrons fall back to their lower energy state they emit a photon of a different wavelength. This is called spontaneous emission. when these emitted photons interact with other high energy state electrons, they cause them to fall back to their lower energy state and emit a photon with the same direction, wavelength and polarisation. This is called stimulated emission. This way you get a high power beam, with very little modal dispersion.

  • @aleksandersuur9475

    @aleksandersuur9475

    6 ай бұрын

    The utility of a laser in most applications is that you get to focus a lot of energy all in one place, higher intensity the better for most uses. If you think to focus a bunch of different laser diodes all in one spot of some tens of microns in dimeter and totaling a kilowatt or so, you are not really going to succeed at that. But if you use the same diodes to pump a fiber laser, then the output from that fiber laser you can focus all in one spot. Note, that the cladding the pump light travels in is a lot thicker than the core where the laser emission travels at. Don't get confused by the pump diodes being lasers themselves, you could be talking about a ruby laser bumped by a a flash tube, or a gas laser, it's going to be the same situation. The laser emission can be focused down to smaller spot for higher intensity than the pump energy can, that's the point of using lasers to pump a laser.

  • @JoJo-zv5sh
    @JoJo-zv5sh5 жыл бұрын

    what language is that ?

  • @Chaos------
    @Chaos------6 жыл бұрын

    Such a gritty level of engineering goes into these things. I really wanna see them produce the fused bionic coupler and what goes into its fabrication but I doubt that information is freely available.

  • @scottwillis5434

    @scottwillis5434

    4 жыл бұрын

    *biconic

  • @halamkajohn
    @halamkajohn4 жыл бұрын

    question answer it takes experiments to add lasers to a high output. like 100 x 50 watt co2 lasers

  • @rnicko86
    @rnicko865 жыл бұрын

    I request permission this content video will be translate with indonesia language..

  • @bhartveersingh1865
    @bhartveersingh18652 жыл бұрын

    Good physics love you from India Punjab Amritsar

  • @BAGINAZARD
    @BAGINAZARD4 жыл бұрын

    My mind is blown.

  • @mikem2136
    @mikem21367 жыл бұрын

    When describing the absorption length of a typical fiber laser, "13 db" is shown above the diameter of the loop in the example fiber (around 6:27 into the video). What is this unit of "db"? I cannot seem to figure it out. The unit of dB (decibels) doesn't seem to make sense here, but that's the only unit that I can find is abbreviated by the letters "DB". Is it 13 decibels?

  • @littlestworkshop

    @littlestworkshop

    6 жыл бұрын

    This is decibel yes. Decibel is not a physical unit but a way of expressing a ratio between two quantities using logarithms. For sound it is used like a unit because the sound is compared to some reference (e.g. dBm means compared to 1mW). In this case it refers to a loss, the ratio of the input power to output power through the fibre. The advantage of using dB is that it allows you to add the losses so a 6dB loss followed by another 6dB loss is a 12dB loss whereas a loss of 0.5 followed by a loss of 0.5 is a loss of 0.25 which is less obvious for non trivial examples.

  • @Kmn0219
    @Kmn02194 жыл бұрын

    I am an electrical engineer and I want to design my own fiber laser cutting machine. Where can I find diagrams and a working knowledge of building the fiber laser source? Thank you.

  • @thomasss9293

    @thomasss9293

    3 жыл бұрын

    Did you figure it out? I'm looking to do the same thing.

  • @Kmn0219

    @Kmn0219

    3 жыл бұрын

    @@thomasss9293 no lol

  • @aleksandersuur9475

    @aleksandersuur9475

    6 ай бұрын

    lulz drawings. Can you dope your own core and draw your own fiber? This is like next level glasswork, your chances of home shopping that are about nil nor is it something you can buy as a part and the challenges don't stop there. Chinesium laser sources start from few thousands, that's your best bet for a realistic staring point..

  • @Mizar88
    @Mizar886 жыл бұрын

    not bad!!

  • @littlestworkshop
    @littlestworkshop6 жыл бұрын

    Very good indeed. Not sure about the use of the term micrometer, micro metre or micron would sound better.

  • @arghyashakharu5564
    @arghyashakharu55642 жыл бұрын

    can you refer some book to understand fiber laser from scratch?It will be very helpful for me then.

  • @rock3tcatU233
    @rock3tcatU2334 жыл бұрын

    Teach me your wizardly ways sensei.

  • @mohammadadankhan8053
    @mohammadadankhan8053 Жыл бұрын

    Nice

  • @noahcorbucci2106
    @noahcorbucci21065 жыл бұрын

    Can you build a fiber laser big as a 10 store building???

  • @YOU_CREATE_YOUR_OWN_KARMA_369

    @YOU_CREATE_YOUR_OWN_KARMA_369

    3 жыл бұрын

    OFC!! We can do ANYTHING that we put our 🧠 to & BELIEVE!

  • @videakias3000
    @videakias30004 жыл бұрын

    8:35 diameter output? what does that even mean?

  • @tombeckmann274

    @tombeckmann274

    3 жыл бұрын

    I think they meant larger diameter core. Large diameter core is easier for coupling the light into the fiber after it is generated from the laser diode's emitters.

  • @dtiydr
    @dtiydr8 жыл бұрын

    Interesting.

  • @gigafridge
    @gigafridge8 жыл бұрын

    i dont get it :'(

  • @marvinxo7624
    @marvinxo76245 жыл бұрын

    Lol, for faster and direct explanation, laser cutting machine, is a combination of Oxygen or just ordinary Air pressure etc. for cutting,, and a fiber laser beam ((meaning came from a multiple light beam into one direction)) or a large laser tube beam for melting, burning.

  • @KarasCyborg
    @KarasCyborg3 жыл бұрын

    Why can't they feed back those photos that jump out of their lane back into the 6:1 coupler somewhere?

  • @MadScientist267
    @MadScientist2673 жыл бұрын

    Informative video but the flickery green ball was very distracting

  • @sergvlasov6776
    @sergvlasov6776 Жыл бұрын

    👍!

  • @icysteve46
    @icysteve463 жыл бұрын

    WOW. ALL THAT TO MAKE MY LASER POINTER WORK.

  • @Kimera_Alternate_Realities
    @Kimera_Alternate_Realities Жыл бұрын

    Amazing, to think you can now buy a home use Fiber Laser

  • @rgbplaza5945
    @rgbplaza59455 жыл бұрын

    Yes love me some ramen scattering

  • @anthonynkurt
    @anthonynkurt4 жыл бұрын

    Haven't seen anyone mention health effects of this light pulsing and laser technology when you are stuck inside your SMART home. ????

  • @eloyex
    @eloyex7 жыл бұрын

    actually is a VERY good presentation . but is not for the common or day to day technician... is more for a specialist or a trainer for the field. very good anyway ....

  • @DeepakKumarSingh2015
    @DeepakKumarSingh20153 жыл бұрын

    #dwdmotnc#discreteoptical #Norteltn #Ciena32slot #ECIXDM1000

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