[HN Gopher] Ph.D student demonstrates a single, working laser on... ___________________________________________________________________ Ph.D student demonstrates a single, working laser on silicon Author : croes Score : 117 points Date : 2021-11-29 18:24 UTC (4 hours ago) (HTM) web link (brighterworld.mcmaster.ca) (TXT) w3m dump (brighterworld.mcmaster.ca) | 908B64B197 wrote: | I'm extremely skeptical, because I've heard claims of silicon | lasers for a long time but it never materialized. | | Also the article seems to plug unrelated scientists with vague | affiliations to the University and a weird political spin to the | whole thing regarding the author's home country's relationship | with the US... despite it not being a US university. | | Weird. | tzs wrote: | > Also the article seems to plug unrelated scientists with | vague affiliations to the University. | | The only other scientists I noticed were her supervisor and the | coauthors of the paper on her research. Did I miss someone? | | > a weird political spin to the whole thing regarding the | author's home country's relationship with the US... despite it | not being a US university | | That was in the short biographical section at the end, | describing where she got her undergraduate degree and how she | ended up McMasters. It is hardly a "weird political spin" to | note that she considered US universities but could not get a | visa. | spicybright wrote: | I doubt GP would have even commented if she had a more | typical bio. | 908B64B197 wrote: | > The only other scientists I noticed were her supervisor and | the coauthors of the paper on her research. Did I miss | someone? | | "Miarabbas Kiani's curiosity-based research is reflected in | the story of another McMaster student. Donna Strickland | received her BEng in Engineering Physics from McMaster in | 1981 and went on to doctoral studies at the University of | Rochester. Strickland's work on pulsed lasers with her PhD | supervisor Gerard Mourou would lead to their Nobel Prize in | Physics in 2018" | | I guess they wanted to have the "Nobel" keyword in there so | they found the closest person to the institution (some | undergrad from 40 years ago)? | | > That was in the short biographical section at the end, | describing where she got her undergraduate degree and how she | ended up McMasters. It is hardly a "weird political spin" to | note that she considered US universities but could not get a | visa. | | I just don't know if my alma mater would brag that "hey, | since this guy couldn't get into somewhere else so he picked | us!". I get that it's an undergrad's joke to laugh at "The | Other Institute of Technology" but for a press release? The | whole thing about the visa thing feels forced. | allemagne wrote: | The "weird political spin": | | >Miarabbas Kiani received her master's in electrical | engineering from Shiraz University in Iran, where she | specialized in photonic and optoelectronic devices. Encouraged | by her supervisor to expand her academic horizons, she | considered studying in the U.S. but was unable to obtain a | visa. Her father suggested she think of Canada. | | Presumably, this is some sort of bizarre prompted response and | it's a stretch to think Kiani was simply asked "why did you | decide to study at McMaster University" and this was her actual | experience. | bredren wrote: | I noticed this quote as well. It is pointed. | | You have to read further to see this happened in 2018. | Presumably, this was directed at the policies of the | executive at the time. | 908B64B197 wrote: | Indeed. I wonder if they would have mentioned it had her | visa denial had happened in 2014 rather than 2018, during a | certain administration... | | What's puzzling is that it's not a US University. I can't | recall any US University press release about innovation in | physics mentioning some foreign country's policy in a weird | political ending. Maybe it's cultural? | indymike wrote: | Any press release that evokes a response of "oh yeah, my master | he already has one and it's very nice-ahhh" is probably heavy on | hype and light on substance. | spicybright wrote: | What do you mean master? | dang wrote: | " _Please don 't post shallow dismissals, especially of other | people's work. A good critical comment teaches us something._" | | https://news.ycombinator.com/newsguidelines.html | _Microft wrote: | Paper: https://onlinelibrary.wiley.com/doi/10.1002/lpor.202100348 | dasudasu wrote: | This is neither low cost nor commercially relevant. It's an | exotic, low-temperature (so incompatible with subsequent steps of | most wafer processes) deposition of rare earth material. The | lasing wavelength is all wrong (1.9 um). It requires a pump laser | in the 1.6 um range which is the usual range of interest. The | efficiency is not very good. Couldn't find the linewidth while | scanning rapidly. It's a run of the mill academic paper. | | There exist commercial electrically pumped lasers on silicon that | are being continuously improved through different approaches. | Intel is one of the leaders on that. | fanzhang wrote: | Is there not a single dimension in which the paper is novel? If | not, it seems like a mistake to publish this. | 908B64B197 wrote: | Not really. It's a different approach with different | tradeoffs that are just as bad as the previously known ones. | | That's probably why it wasn't picked up by a better journal | and that nobody outside of the university where it happened | is talking about it. | echelon wrote: | Not my area of expertise, but something can be academically | novel and interesting without having any commercial or | industrial applicability. | amelius wrote: | Isn't this what usually happens when the PR department of a | university runs away with a story? | redmare80 wrote: | It's novel, it's a huge iteration in the space. But, it's | also being misrepresented as more significant than it is due | to the summary being friendly to laypeople. | dogber1 wrote: | And on top of that, you can make almost any material lase. | There have been entertaining experiments where folks used | yogurt, apple juice, hair dye, and other fun liquids in pumped | lasers, exploiting some molecular band transition that was | accidentally good enough. | sleepysysadmin wrote: | Breakthrough using extremely rare earth | https://en.wikipedia.org/wiki/Thulium which comes at a high price | and only provides a low power laser? | | Wierd that the article says its low cost. Certainly not a holy | grail. | jjk166 wrote: | The term rare earth is a bit misleading. It's not rare as in | uncommon, it's rare as in dilute. | | Rare earths are elements that don't form concentrated ores, and | instead are spread diffusely in common rocks. Most soils | contain between 0.4 and 0.8 ppm Thulium. Luckily Earth has a | lot of rock, so in absolute terms there are still lots of rare | earth material. | | The problem is that rare earths are mined by processing | prodigious amounts of earth, typically the waste from some | other mining activity. Like most large scale mining operations, | it is labor intensive and environmentally destructive. | Naturally this leads to such operations being located where | labor is cheap and environmental regulations are lax. When | people express concern about access to Rare Earths, they really | mean access to materials from countries (often one specific | country) with cheap labor and poor regulation. | | Thulium's expense is due to limited production, as there are | few industrial uses for it and those applications that do | utilize it tend to need only microscopic amounts, but with high | purity. | _Microft wrote: | Thulium is only required in small quantities. Here is a back- | of-the-envelope calculation: molar mass of thulium: 169g/mol, | density: 9.32g/cm3, i.e. 0.055 mol/cm^3 [0]. That's ~ 3.3*10^22 | atoms per cubic centimeter. | | From the article: _A thulium ion dopant concentration of 4.0 x | 10^20 cm-3 was measured using Rutherford backscattering | spectrometry._ [1], i.e. a concentration of roughly 1 /100 | compared to pure material. | | Taking the first search result at face value, a cubic | centimeter of 99.9% pure Thulium costs $85 [2]. Since the disks | seem to have a diameter of 40mm, only a minuscule fraction of a | cubic centimeter of material is needed for each. | | I would conclude that the material costs for these disks are | not as large as initially assumed. | | [0] https://en.wikipedia.org/wiki/Thulium | | [1] | https://onlinelibrary.wiley.com/doi/10.1002/lpor.202100348#p... | (page 8, left column halfway down the page) | | [2] https://luciteria.com/metal-cubes/thulium-metal-cubes | superkuh wrote: | This laser requires a second laser to pump it in order for it to | work. It's kind of defeating the point of things. | m-watson wrote: | A lot of lasers require a pump laser, it seems their argument | is that this can be useful for low cost production in something | like the telcom world. | jacquesm wrote: | Not really. Pumped lasers are the norm for quite a few | materials that are hard to use as primary light source, but as | a secondary lightsource they are plenty useful. | | Note that lots of other lasers are pumped as well, for | instance, some lasers were originally pumped by flashing Xenon | light from spiral wound flash tubes into Ruby crystal rods | grown at great expense to get the gas to emit coherent light. | The energy efficiency is important so that you don't end up | overheating your secondary laser but the principle has plenty | of uses and isn't even restricted to using light as the | starting point. | | One possible way to use this is to use a somewhat higher power | laser to illuminate a substrate at right angles to the desired | outputs, which would allow for a hybrid where only the primary | is made with exotic materials and the remainder can be made in | Silicon. Right now _every_ laser output needs to be on a | physically different die than the Silicon based circuitry that | drives it, this technique could do away with that intermediary | step substantially reducing the costs of certain | telecommunications devices. | | Finally, once something has been pushed to lase it usually | doesn't take very long before improvements are made that allow | it to do so cheaper, faster or independent of the original | light source, it is that first step that is the really hard | one. | | One joke I heard from someone who is deep inside laser research | is that when all is said and done there are probably not a | whole lot of substances that can't be made to emit coherent | light, the trick is to find out how to do it in the first | place, and then to do it repeatedly and affordably. | ourmandave wrote: | The real test will be if they can mount it on a jet and do a fly- | by to fill an entire house with popcorn. | oneshoe wrote: | Deep reference! This comment made my morning. Thank you! | beckingz wrote: | Silicon photonics (microchip lasers and particle accelerators) is | an active area of research that has had some promising | improvements lately. | | Research like this is likely to result in a laser miniaturization | breakthrough like that of MEMs sensors, which will have big | impacts if the money and energy cost of a putting a laser on a | device drops to near zero. | | Great talk on the state of the art: | https://www.youtube.com/watch?v=t5EPeuLxaE0 | savant_penguin wrote: | Really cool, but the article could show a picture of the actual | laser light (maybe it's not visible light?) | hellbannedguy wrote: | Or at least a clear picture of the dime. | jacquesm wrote: | It appears to be emitting in the IR part of the spectrum (1.9 | um). | spoonjim wrote: | > Encouraged by her supervisor to expand her academic horizons, | she considered studying in the U.S. but was unable to obtain a | visa. | | > | | > Her father suggested she think of Canada. | msie wrote: | I'm skeptical of university press releases. Is this the "holy | grail" as they claim it to be? :D | crispyambulance wrote: | It might very well be a big deal. | | This has been done with Indium Phosphide (InP). In fact, | lasers, modulators and supporting circuitry have have been | integrated together on InP in what is usually referred to as | "Photonic Integrated Circuits". Infinera has been doing this | for ~20 years. The drawback is you need a very specialized InP | fab (which ultimately means high-cost and low volume). | | If similar stuff could be done on ordinary silicon, that | changes the game and opens up a huge range of possibilities. | slownews45 wrote: | Does it need to be ordinary silicon, or ordinary silicon | processes (including temperature?). One seems much easier | than the other, the later seems much more likely to be cheap | (I can build a big laser on ordinary silicon today). Much | harder to do with ordinary silicon in a somewhat standard | process flow. | klyrs wrote: | To be fair, it's a "holy Grail" of the very niche field of | photonics. On the other hand, the lack of easily-integrated | lasers has been a major hurdle to photonics becoming anything | other than a niche field. | | After all, the first transistor wasn't remotely competitive | with existing vacuum diodes in use at the time. | timdellinger wrote: | I'll also add that "holy grail" type discoveries tend to be | published in higher tier journals than this one. | bell-cot wrote: | For a so-so discovery, you need the cred of a high-tier | journal far more than they need your paper. | | For an actual holy grail, ~every journal in the field needs | the cred of your paper far more than you need them. | bredren wrote: | If you have a holy-grail, do journals like Nature do things | to try to lure you into publishing with them instead of the | one this author chose? | jacquesm wrote: | This is exactly what should stop, so if this is the case of | someone publishing an actual breakthrough in a lower tier | journal then that should be encouraged, rather than punished | by outright dismissing the contribution based on where it is | published. | | Otherwise we'll never get rid of those cartels. | wanderingmind wrote: | That's like asking smart programmers should stop working | for FAANG and work for minimum wage at a non-profit, to | help save the world. The academic perks at multiple levels | are deeply tied to publishing in top tier journals. It's | not going to change unless there is a wholesale | reorganization of incentives, which is unlikely to happen. | Open sourcing the research publications for taxpayer funded | research is probably what we can strive to achieve. | earthscienceman wrote: | Ehhhh. Not at all true. Or at least that's maybe 50% true. | Many high impact papers in my field, including "holy grail" | type papers, have been published in "low tier" journals. Some | scientists would much rather publish quality research in a | timely manner than go through the Nature review process and | waste a lot of their time. It's extremely dependent on the | disposition of the lead author. | | For the record I can't at all speak to the quality of this | research paper, I'm only trying to address this comment | specifically. | SubiculumCode wrote: | So true ___________________________________________________________________ (page generated 2021-11-29 23:00 UTC)