Gustafson Endowed Chair in Quantum Engineering<\/a> at CU Boulder. \u201cThey\u2019re in all modern cell phones, key fobs, garage door openers, most GPS receivers, many radar systems and more.\u201d<\/p>\nIn a smartphone, SAWs already act as little filters. Radios inside your phone receive radio waves coming from a cell tower. They then convert those signals into tiny vibrations, which allows chips to easily remove unwanted signals and noise. Then, the same device turns those vibrations back into radio waves.<\/p>\n
In the current study, Eichenfield and his team developed a new way of making SAWs using a \u201cphonon laser.\u201d It works like a run-of-the-mill laser pointer, except that it generates vibrations.<\/p>\n
\u201cThink of it almost like the waves from an earthquake, only on the surface of a small chip,\u201d said Alexander Wendt, a graduate student at the University of Arizona and lead author of the new study.<\/p>\n
Most SAWs devices today require two different chips and a power source to generate these waves. The team\u2019s device, in contrast, works using just a single chip and can potentially produce SAWs at much higher frequencies paired only with a battery.<\/p>\n
A new kind of laser<\/p>\n
To understand how the team\u2019s new SAW device works, it helps to think about a traditional laser.<\/p>\n
Most lasers around today, known as \u201cdiode lasers,\u201d work by bouncing a beam of light between two microscopic mirrors on the surface of a semiconductor chip. As that light bounces back and forth, it bangs into atoms in the semiconductor material that have an electric field running through them from a battery or other power source. In the process, those atoms eject even more light, and the beam becomes more powerful.<\/p>\n
\u201cDiode lasers are the cornerstone of most optical technologies because they can be operated with just a battery or simple voltage source, rather than needing more light to create the laser like a lot of previous kinds of lasers,\u201d Eichenfield said. \u201cWe wanted to make an analog of that kind of laser but for SAWs.\u201d<\/p>\n
To do that, the team developed a device that\u2019s shaped like a bar and measures about half a millimeter from end to end.<\/p>\n
The device is a stack of materials: In its finished form, it\u2019s made from a wafer of silicon, the same material in most computer chips. On top of that is a thin layer of a material called lithium niobate. Lithium niobate is a \u201cpiezoelectric\u201d material, which means that when it vibrates, it also produces oscillating electric fields. Equivalently, when oscillating electric fields are present, they create vibrations.<\/p>\n
Last, the device includes an even thinner layer of indium gallium arsenide\u2014an unusual material that, when hit with a weak electric field, can accelerate electrons to incredibly fast speeds.<\/p>\n
Altogether, the team\u2019s stack allows vibrations on the surface of the lithium niobate to directly interact with electrons in the indium gallium arsenide.<\/p>\n
Doing the wave<\/p>\n
The device works a bit like a wave pool.<\/p>\n
When the researchers pump their device with an electric current in the indium gallium arsenide, waves will form in the thin layer of lithium niobate. Those waves slosh forward, hit a reflector, then slosh back\u2014similar to light bouncing between two mirrors in a laser. Every time those waves move forward, they get stronger. Every time they move backward, they get a little weaker.<\/p>\n
\u201cIt loses almost 99% of its power when it\u2019s moving backward, so we designed it to get a substantial amount of gain moving forward to beat that,\u201d Wendt said.<\/p>\n
After several bounces, the wave becomes very large. The device lets a little of that wave leak out one side, which is equivalent to how laser light builds up and leaks out from between its mirrors.<\/p>\n
The group was able to generate SAWs that rippled at a rate of about 1 gigahertz, or billions of times per second. But the researchers also think they can easily increase that to frequencies in the many tens of gigahertz or even hundreds of gigahertz.<\/p>\n","protected":false},"excerpt":{"rendered":"A team of engineers has made major strides in generating the tiniest earthquakes imaginable.\u00a0 The team\u2019s device, known…\n","protected":false},"author":2,"featured_media":409719,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[49,48,61],"class_list":["post-409718","post","type-post","status-publish","format-standard","has-post-thumbnail","category-technology","tag-ca","tag-canada","tag-technology"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/409718","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/comments?post=409718"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/posts\/409718\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media\/409719"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/media?parent=409718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/categories?post=409718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ca\/wp-json\/wp\/v2\/tags?post=409718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}