{"id":22178,"date":"2018-02-03T03:07:16","date_gmt":"2018-02-03T03:07:16","guid":{"rendered":"http:\/\/www.kurzweilai.net\/?p=308521"},"modified":"2018-02-06T07:50:40","modified_gmt":"2018-02-06T07:50:40","slug":"penn-researchers-create-first-optical-transistor-comparable-to-an-electronic-transistor","status":"publish","type":"post","link":"https:\/\/hoo.central12.com\/fugic\/2018\/02\/03\/penn-researchers-create-first-optical-transistor-comparable-to-an-electronic-transistor\/","title":{"rendered":"Penn researchers create first optical transistor comparable to an electronic transistor"},"content":{"rendered":"
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By precisely controlling the mixing of optical signals, Ritesh Agarwal’s research team says they have taken an important step toward\u00a0photonic (optical) computing. (credit: Sajal Dhara)<\/p><\/div>\n

In an\u00a0open-access paper published in Nature Communications<\/em><\/a>, <\/em>Ritesh Agarwal<\/a>, a professor the University of Pennsylvania School of Engineering and Applied Science, and his colleagues say that they have made significant progress in photonic (optical) computing<\/a> by creating a prototype of a working optical transistor with properties similar to those of a conventional electronic transistor.*<\/p>\n

Optical transistors, using photons instead of electrons, promise to one day be more powerful than the electronic transistors currently used in computers.<\/p>\n

Agarwal\u2019s research on photonic computing has been focused on finding the right combination and physical configuration of nonlinear materials that can amplify and mix light waves in ways that are analogous to electronic transistors. \u201cOne of the hurdles in doing this with light is that materials that are able to mix optical signals also tend to have very strong background signals as well. That background signal would drastically reduce the contrast and on\/off ratios leading to errors in the output,\u201d Agarwal explained.<\/p>\n

How the new optical transistor works<\/strong><\/p>\n

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Schematic of a cadmium sulfide nanobelt device with source (S) and drain (D) electrodes. The fundamental wave at the frequency of \u03c9, which is normally incident upon the belt, excites the second-harmonic (twice the frequency) wave at 2\u03c9, which is back-scattered. (credit: Ming-Liang Ren et al.\/Nature Communications)<\/p><\/div>\n

To address this issue, Agarwal\u2019s research group started by creating a system with no disruptive optical background signal. To do that, they used a \u201cnanobelt\u201d* made out of cadmium sulfide. Then, by applying an electrical field across the nanobelt, the researchers were able to introduce optical nonlinearities (similar to the nonlinearities in electronic transistors), which enabled a signal mixing output that was otherwise zero.<\/p>\n

\u201cOur system turns on from zero to extremely large values,\u201d Agarwal said.** \u201cFor the first time, we have an optical device with output that truly resembles an electronic transistor.\u201d<\/p>\n

The next steps toward a fully functioning photonic computer will involve integrating optical circuits with optical interconnects, modulators, and detectors to achieve actual on-chip integrated photonic computation.<\/p>\n

The research was supported by the US Army Research Office and the National Science Foundation.<\/p>\n

* “Made of semiconducting metal oxides, nanobelts are extremely thin and flat structures. They are chemically pure, structurally uniform, largely defect-free, with clean surfaces that do not require protection against oxidation. Each is made up of a single crystal with specific surface planes and shape.” —\u00a0Reade International Corp.<\/em><\/p>\n

** That is, the system was capable of precisely controlling the mixing of optical signals via controlled electric fields, with outputs with near-perfect contrast and extremely large on\/off ratios. “Our study demonstrates a new way to dynamically control nonlinear optical signals in nanoscale materials with ultrahigh signal contrast and signal saturation, which can enable the development of nonlinear optical transistors and modulators for on-chip photonic devices with high-performance metrics and small-form factors, which can be further enhanced by integrating with nanoscale optical cavities,” the researchers note in the paper.<\/em><\/p>\n

\n

Abstract of\u00a0Strong modulation of second-harmonic generation with very large contrast in semiconducting CdS via high-field domain<\/em><\/h4>\n

Dynamic control of nonlinear signals is critical for a wide variety of optoelectronic applications, such as signal processing for optical computing. However, controlling nonlinear optical signals with large modulation strengths and near-perfect contrast remains a challenging problem due to intrinsic second-order nonlinear coefficients via bulk or surface contributions. Here, via electrical control, we turn on and tune second-order nonlinear coefficients in semiconducting CdS nanobelts from zero to up to 151\u2009pm\u2009V\u22121<\/sup>, a value higher than other intrinsic nonlinear coefficients in CdS. We also observe ultrahigh ON\/OFF ratio of >104<\/sup> and modulation strengths ~200%\u2009V\u22121<\/sup> of the nonlinear signal. The unusual nonlinear behavior, including super-quadratic voltage and power dependence, is ascribed to the high-field domain, which can be further controlled by near-infrared optical excitation and electrical gating. The ability to electrically control nonlinear optical signals in nanostructures can enable optoelectronic devices such as optical transistors and modulators for on-chip integrated photonics.<\/p>\n","protected":false},"excerpt":{"rendered":"

In an open-access paper published in Nature Communications, Ritesh Agarwal, a professor the University of Pennsylvania School of Engineering and Applied Science, and his colleagues say that they have made significant progress in photonic (optical) computing by creating a prototype of a working optical transistor with properties similar to those of a conventional electronic transistor.* Optical […]<\/p>\n","protected":false},"author":13,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47,48,43],"tags":[],"class_list":["post-22178","post","type-post","status-publish","format-standard","hentry","category-computersinfotechui","category-electronics","category-news"],"_links":{"self":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/22178"}],"collection":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/comments?post=22178"}],"version-history":[{"count":2,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/22178\/revisions"}],"predecessor-version":[{"id":22215,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/posts\/22178\/revisions\/22215"}],"wp:attachment":[{"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/media?parent=22178"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/categories?post=22178"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hoo.central12.com\/fugic\/wp-json\/wp\/v2\/tags?post=22178"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}