{"id":88996,"date":"2011-09-01T14:00:02","date_gmt":"2011-09-01T18:00:02","guid":{"rendered":"\/gazette\/?p=88996"},"modified":"2019-06-26T15:11:27","modified_gmt":"2019-06-26T19:11:27","slug":"from-a-flat-mirror-designer-light","status":"publish","type":"post","link":"https:\/\/news.harvard.edu\/gazette\/story\/2011\/09\/from-a-flat-mirror-designer-light\/","title":{"rendered":"From a flat mirror, designer light"},"content":{"rendered":"\n\t
\"\"

"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear," said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. "The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection."<\/p>

Photos by Eliza Grinnell and Nanfang Yu\/SEAS<\/p><\/figcaption><\/figure>\n\n\t

\n\t\t\t\n\t\t\tScience & Tech\t\t<\/a>\n\t\t\n\t\t

\n\t\tFrom a flat mirror, designer light\t<\/h1>\n\n\t\n\t\t\t<\/div>\n\t\t\n\t
\n\t\t
\n\t\t\t
\n\t\t\t\t\t

\n\t\tCaroline Perry\t<\/p>\n\t\t\t

\n\t\t\tSEAS Communications\t\t<\/p>\n\t\t\t\t\t<\/address>\n\t\t<\/div>\n\n\t\t

\n\t\t\tAn optical phenomenon that defies laws of reflection and refraction\t\t<\/h2>\n\t\t\n<\/header>\n\n\n\n
\n\n\n\t\t

Exploiting a novel technique called phase discontinuity, researchers at the Harvard School of Engineering and Applied Sciences<\/a> (SEAS) have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n

The discovery, published Sept. 2 in the journal Science, has led to a reformulation of the mathematical laws that predict the path of a ray of light bouncing off a surface or traveling from one medium into another \u2014 for example, from air into glass.<\/p>\n

“Using designer surfaces, we’ve created the effects of a fun-house mirror on a flat plane,” said co-principal investigator Federico Capasso<\/a>, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. “Our discovery carries optics into new territory and opens the door to exciting developments in photonics technology.”<\/p>\n

It has been recognized since ancient times that light travels at different speeds through different media. Reflection and refraction occur whenever light encounters a material at an angle, because one side of the beam is able to race ahead of the other. As a result, the wave front changes direction.<\/p>\n

The conventional laws, taught in physics classrooms worldwide, predict the angles of reflection and refraction based only on the incident (incoming) angle and the properties of the two media.<\/p>\n

While studying the behavior of light impinging on surfaces patterned with metallic nanostructures, the researchers realized that the usual equations were insufficient to describe the bizarre phenomena observed in the lab.<\/p>\n

The new generalized laws, derived and experimentally demonstrated at Harvard, take into account the Capasso group’s discovery that the boundary between two media, if specially patterned, can itself behave like a third medium.<\/p>\n

“Ordinarily, a surface like the surface of a pond is simply a geometric boundary between two media, air and water,” said lead author Nanfang Yu, Ph.D. ’09, a research associate in Capasso’s lab at SEAS. “But now, in this special case, the boundary becomes an active interface that can bend the light by itself.”<\/p>\n

The key component is an array of tiny gold antennas etched into the surface of the silicon used in Capasso’s lab. The array is structured on a scale much thinner than the wavelength of the light hitting it. This means that, unlike in a conventional optical system, the engineered boundary between the air and the silicon imparts an abrupt phase shift \u2014 dubbed “phase discontinuity” \u2014 to the crests of the light wave crossing it.<\/p>\n

Each antenna in the array is a tiny resonator that can trap the light, holding its energy for a given amount of time before releasing it. A gradient of different types of nanoscale resonators across the surface of the silicon can effectively bend the light before it even begins to propagate through the new medium.<\/p>\n

The resulting phenomenon breaks the old rules, creating beams of light that reflect and refract in arbitrary ways, depending on the surface pattern.<\/p>\n

In order to generalize the textbook laws of reflection and refraction, the Harvard researchers added a new term to the equations, representing the gradient of phase shifts imparted at the boundary. Importantly, in the absence of a surface gradient, the new laws reduce to the well-known ones.<\/p>\n

“By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear,” said Zeno Gaburro, a visiting scholar in Capasso’s group who was co-principal investigator for this work. “The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection.”<\/p>\n\r\n\t\n\n\t

\"\"
Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS\t\t\t<\/figcaption><\/figure>\n\t\n\t\r\n\n

Moreover, the frequency (color), amplitude (brightness), and polarization of the light can also be controlled, meaning that the output is in essence a designer beam.<\/p>\n

The researchers have already succeeded at producing a vortex beam (a helical, corkscrew-shaped stream of light) from a flat surface. They also envision flat lenses that could focus an image without aberrations.<\/p>\n

Yu, Capasso, and Gaburro’s co-authors included Patrice Genevet, Mikhail A. Kats, Francesco Aieta, and Jean-Philippe Tetienne.<\/p>\n

The research was supported by the National Science Foundation<\/a> (NSF), the NSF-funded Harvard Nanoscale Science and Engineering Center<\/a>, the Center for Nanoscale Systems at Harvard (part of the NSF-funded National Nanotechnology Infrastructure Network), the European Communities Seventh Framework Programme, and the Harvard Faculty of Arts and Sciences’ Science Division Research Computing Group.<\/p>\n\n\n<\/div>\n\n\t\t","protected":false},"excerpt":{"rendered":"

Using a new technique, researchers at the Harvard School of Engineering and Applied Sciences have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n","protected":false},"author":105622744,"featured_media":89001,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"gz_ga_pageviews":10,"gz_ga_lastupdated":"2019-12-27 20:09","document_color_palette":"crimson","author":"Caroline Perry","affiliation":"SEAS 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There is a new angle of total internal reflection.\"","mediaId":89001,"mediaSize":"full","mediaType":"image","mediaUrl":"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/08\/seas-photo4_605.jpg","poster":"","title":"From a flat mirror, designer light","subheading":"An optical phenomenon that defies laws of reflection and refraction","centeredImage":true,"className":"is-style-full-width-text-below","mediaHeight":403,"mediaWidth":605,"backgroundFixed":false,"backgroundTone":"light","coloredBackground":false,"displayOverlay":true,"fadeInText":false,"isAmbient":false,"mediaLength":"","mediaPosition":"","posterText":"","titleAbove":false,"useUncroppedImage":false,"lock":[],"metadata":[]},"innerBlocks":[],"innerHTML":"<figure class=\"wp-block-image\"><img alt=\"\" height=\"403\" loading=\"eager\" src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/08\/seas-photo4_605.jpg\" width=\"605\"\/><figcaption class=\"wp-element-caption\"><p class=\"wp-element-caption--caption\">"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear," said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. "The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection."<\/p><p class=\"wp-element-caption--credit\">Photos by Eliza Grinnell and Nanfang Yu\/SEAS<\/p><\/figcaption><\/figure>\n","innerContent":["<figure class=\"wp-block-image\"><img alt=\"\" height=\"403\" loading=\"eager\" src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/08\/seas-photo4_605.jpg\" width=\"605\"\/><figcaption class=\"wp-element-caption\"><p class=\"wp-element-caption--caption\">"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear," said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. "The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection."<\/p><p class=\"wp-element-caption--credit\">Photos by Eliza Grinnell and Nanfang Yu\/SEAS<\/p><\/figcaption><\/figure>\n"],"rendered":"<header\n\tclass=\"wp-block-harvard-gazette-article-header alignfull article-header is-style-full-width-text-below centered-image\"\n\tstyle=\" \"\n>\n\t<figure class=\"wp-block-image\"><img alt=\"\" height=\"403\" loading=\"eager\" src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/08\/seas-photo4_605.jpg\" width=\"605\"\/><figcaption class=\"wp-element-caption\"><p class=\"wp-element-caption--caption\">"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear," said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. "The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection."<\/p><p class=\"wp-element-caption--credit\">Photos by Eliza Grinnell and Nanfang Yu\/SEAS<\/p><\/figcaption><\/figure>\n\n\t<div class=\"article-header__content\">\n\t\t\t<a\n\t\t\tclass=\"article-header__category\"\n\t\t\thref=\"https:\/\/news.harvard.edu\/gazette\/section\/science-technology\/\"\n\t\t>\n\t\t\tScience & Tech\t\t<\/a>\n\t\t\n\t\t<h1 class=\"article-header__title wp-block-heading \">\n\t\tFrom a flat mirror, designer light\t<\/h1>\n\n\t\n\t\t\t<\/div>\n\t\t\n\t<div class=\"article-header__meta\">\n\t\t<div class=\"wp-block-post-author\">\n\t\t\t<address class=\"wp-block-post-author__content\">\n\t\t\t\t\t<p class=\"author wp-block-post-author__name\">\n\t\tCaroline Perry\t<\/p>\n\t\t\t<p class=\"wp-block-post-author__byline\">\n\t\t\tSEAS Communications\t\t<\/p>\n\t\t\t\t\t<\/address>\n\t\t<\/div>\n\n\t\t<time class=\"article-header__date\" datetime=\"2011-09-01\">\n\t\t\tSeptember 1, 2011\t\t<\/time>\n\n\t\t<span class=\"article-header__reading-time\">\n\t\t\t5 min read\t\t<\/span>\n\t<\/div>\n\n\t\n\t\t\t<h2 class=\"article-header__subheading wp-block-heading\">\n\t\t\tAn optical phenomenon that defies laws of reflection and refraction\t\t<\/h2>\n\t\t\n<\/header>\n"},"2":{"blockName":"core\/group","attrs":{"templateLock":false,"metadata":{"name":"Article content"},"align":"wide","layout":{"type":"constrained","justifyContent":"center"},"tagName":"div","lock":[],"className":"","style":[],"backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","ariaLabel":"","anchor":""},"innerBlocks":[{"blockName":"core\/freeform","attrs":{"content":"","lock":[],"metadata":[]},"innerBlocks":[],"innerHTML":"\n\t\t<p>Exploiting a novel technique called phase discontinuity, researchers at the Harvard <a href=\"http:\/\/www.seas.harvard.edu\/\">School of Engineering and Applied Sciences<\/a> (SEAS) have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n<p>The discovery, published Sept. 2 in the journal Science, has led to a reformulation of the mathematical laws that predict the path of a ray of light bouncing off a surface or traveling from one medium into another \u2014 for example, from air into glass.<\/p>\n<p>\"Using designer surfaces, we've created the effects of a fun-house mirror on a flat plane,\" said co-principal investigator <a href=\"http:\/\/www.seas.harvard.edu\/capasso\/\">Federico Capasso<\/a>, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. \"Our discovery carries optics into new territory and opens the door to exciting developments in photonics technology.\"<\/p>\n<p>It has been recognized since ancient times that light travels at different speeds through different media. Reflection and refraction occur whenever light encounters a material at an angle, because one side of the beam is able to race ahead of the other. As a result, the wave front changes direction.<\/p>\n<p>The conventional laws, taught in physics classrooms worldwide, predict the angles of reflection and refraction based only on the incident (incoming) angle and the properties of the two media.<\/p>\n<p>While studying the behavior of light impinging on surfaces patterned with metallic nanostructures, the researchers realized that the usual equations were insufficient to describe the bizarre phenomena observed in the lab.<\/p>\n<p>The new generalized laws, derived and experimentally demonstrated at Harvard, take into account the Capasso group's discovery that the boundary between two media, if specially patterned, can itself behave like a third medium.<\/p>\n<p>\"Ordinarily, a surface like the surface of a pond is simply a geometric boundary between two media, air and water,\" said lead author Nanfang Yu, Ph.D. '09, a research associate in Capasso's lab at SEAS. \"But now, in this special case, the boundary becomes an active interface that can bend the light by itself.\"<\/p>\n<p>The key component is an array of tiny gold antennas etched into the surface of the silicon used in Capasso's lab. The array is structured on a scale much thinner than the wavelength of the light hitting it. This means that, unlike in a conventional optical system, the engineered boundary between the air and the silicon imparts an abrupt phase shift \u2014 dubbed \"phase discontinuity\" \u2014 to the crests of the light wave crossing it.<\/p>\n<p>Each antenna in the array is a tiny resonator that can trap the light, holding its energy for a given amount of time before releasing it. A gradient of different types of nanoscale resonators across the surface of the silicon can effectively bend the light before it even begins to propagate through the new medium.<\/p>\n<p>The resulting phenomenon breaks the old rules, creating beams of light that reflect and refract in arbitrary ways, depending on the surface pattern.<\/p>\n<p>In order to generalize the textbook laws of reflection and refraction, the Harvard researchers added a new term to the equations, representing the gradient of phase shifts imparted at the boundary. Importantly, in the absence of a surface gradient, the new laws reduce to the well-known ones.<\/p>\n<p>\"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear,\" said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. \"The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection.\"<\/p>\n","innerContent":["\n\t\t<p>Exploiting a novel technique called phase discontinuity, researchers at the Harvard <a href=\"http:\/\/www.seas.harvard.edu\/\">School of Engineering and Applied Sciences<\/a> (SEAS) have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n<p>The discovery, published Sept. 2 in the journal Science, has led to a reformulation of the mathematical laws that predict the path of a ray of light bouncing off a surface or traveling from one medium into another \u2014 for example, from air into glass.<\/p>\n<p>\"Using designer surfaces, we've created the effects of a fun-house mirror on a flat plane,\" said co-principal investigator <a href=\"http:\/\/www.seas.harvard.edu\/capasso\/\">Federico Capasso<\/a>, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. \"Our discovery carries optics into new territory and opens the door to exciting developments in photonics technology.\"<\/p>\n<p>It has been recognized since ancient times that light travels at different speeds through different media. Reflection and refraction occur whenever light encounters a material at an angle, because one side of the beam is able to race ahead of the other. As a result, the wave front changes direction.<\/p>\n<p>The conventional laws, taught in physics classrooms worldwide, predict the angles of reflection and refraction based only on the incident (incoming) angle and the properties of the two media.<\/p>\n<p>While studying the behavior of light impinging on surfaces patterned with metallic nanostructures, the researchers realized that the usual equations were insufficient to describe the bizarre phenomena observed in the lab.<\/p>\n<p>The new generalized laws, derived and experimentally demonstrated at Harvard, take into account the Capasso group's discovery that the boundary between two media, if specially patterned, can itself behave like a third medium.<\/p>\n<p>\"Ordinarily, a surface like the surface of a pond is simply a geometric boundary between two media, air and water,\" said lead author Nanfang Yu, Ph.D. '09, a research associate in Capasso's lab at SEAS. \"But now, in this special case, the boundary becomes an active interface that can bend the light by itself.\"<\/p>\n<p>The key component is an array of tiny gold antennas etched into the surface of the silicon used in Capasso's lab. The array is structured on a scale much thinner than the wavelength of the light hitting it. This means that, unlike in a conventional optical system, the engineered boundary between the air and the silicon imparts an abrupt phase shift \u2014 dubbed \"phase discontinuity\" \u2014 to the crests of the light wave crossing it.<\/p>\n<p>Each antenna in the array is a tiny resonator that can trap the light, holding its energy for a given amount of time before releasing it. A gradient of different types of nanoscale resonators across the surface of the silicon can effectively bend the light before it even begins to propagate through the new medium.<\/p>\n<p>The resulting phenomenon breaks the old rules, creating beams of light that reflect and refract in arbitrary ways, depending on the surface pattern.<\/p>\n<p>In order to generalize the textbook laws of reflection and refraction, the Harvard researchers added a new term to the equations, representing the gradient of phase shifts imparted at the boundary. Importantly, in the absence of a surface gradient, the new laws reduce to the well-known ones.<\/p>\n<p>\"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear,\" said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. \"The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection.\"<\/p>\n"],"rendered":"\n\t\t<p>Exploiting a novel technique called phase discontinuity, researchers at the Harvard <a href=\"http:\/\/www.seas.harvard.edu\/\">School of Engineering and Applied Sciences<\/a> (SEAS) have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n<p>The discovery, published Sept. 2 in the journal Science, has led to a reformulation of the mathematical laws that predict the path of a ray of light bouncing off a surface or traveling from one medium into another \u2014 for example, from air into glass.<\/p>\n<p>\"Using designer surfaces, we've created the effects of a fun-house mirror on a flat plane,\" said co-principal investigator <a href=\"http:\/\/www.seas.harvard.edu\/capasso\/\">Federico Capasso<\/a>, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. \"Our discovery carries optics into new territory and opens the door to exciting developments in photonics technology.\"<\/p>\n<p>It has been recognized since ancient times that light travels at different speeds through different media. Reflection and refraction occur whenever light encounters a material at an angle, because one side of the beam is able to race ahead of the other. As a result, the wave front changes direction.<\/p>\n<p>The conventional laws, taught in physics classrooms worldwide, predict the angles of reflection and refraction based only on the incident (incoming) angle and the properties of the two media.<\/p>\n<p>While studying the behavior of light impinging on surfaces patterned with metallic nanostructures, the researchers realized that the usual equations were insufficient to describe the bizarre phenomena observed in the lab.<\/p>\n<p>The new generalized laws, derived and experimentally demonstrated at Harvard, take into account the Capasso group's discovery that the boundary between two media, if specially patterned, can itself behave like a third medium.<\/p>\n<p>\"Ordinarily, a surface like the surface of a pond is simply a geometric boundary between two media, air and water,\" said lead author Nanfang Yu, Ph.D. '09, a research associate in Capasso's lab at SEAS. \"But now, in this special case, the boundary becomes an active interface that can bend the light by itself.\"<\/p>\n<p>The key component is an array of tiny gold antennas etched into the surface of the silicon used in Capasso's lab. The array is structured on a scale much thinner than the wavelength of the light hitting it. This means that, unlike in a conventional optical system, the engineered boundary between the air and the silicon imparts an abrupt phase shift \u2014 dubbed \"phase discontinuity\" \u2014 to the crests of the light wave crossing it.<\/p>\n<p>Each antenna in the array is a tiny resonator that can trap the light, holding its energy for a given amount of time before releasing it. A gradient of different types of nanoscale resonators across the surface of the silicon can effectively bend the light before it even begins to propagate through the new medium.<\/p>\n<p>The resulting phenomenon breaks the old rules, creating beams of light that reflect and refract in arbitrary ways, depending on the surface pattern.<\/p>\n<p>In order to generalize the textbook laws of reflection and refraction, the Harvard researchers added a new term to the equations, representing the gradient of phase shifts imparted at the boundary. Importantly, in the absence of a surface gradient, the new laws reduce to the well-known ones.<\/p>\n<p>\"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear,\" said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. \"The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection.\"<\/p>\n"},{"blockName":"core\/image","attrs":{"sizeSlug":"full","align":"center","id":89339,"caption":"Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS","blob":"","url":"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/09\/seas-photo4.jpg","alt":"","lightbox":[],"title":"","href":"","rel":"","linkClass":"","width":"","height":"","aspectRatio":"","scale":"","linkDestination":"","linkTarget":"","lock":[],"metadata":[],"className":"","style":[],"borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n\n\t<figure class=\"wp-block-image aligncenter size-full is-resized\"><img src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/09\/seas-photo4.jpg\" alt=\"\" class=\"wp-image-89339\"><figcaption class=\"wp-element-caption\">Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS\t\t\t<\/figcaption><\/figure>\n\t","innerContent":["\n\n\t<figure class=\"wp-block-image aligncenter size-full is-resized\"><img src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/09\/seas-photo4.jpg\" alt=\"\" class=\"wp-image-89339\"><figcaption class=\"wp-element-caption\">Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS\t\t\t<\/figcaption><\/figure>\n\t"],"rendered":"\n\n\t<figure class=\"wp-block-image aligncenter size-full is-resized\"><img src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/09\/seas-photo4.jpg\" alt=\"\" class=\"wp-image-89339\"><figcaption class=\"wp-element-caption\">Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS\t\t\t<\/figcaption><\/figure>\n\t"},{"blockName":"core\/freeform","attrs":{"content":"","lock":[],"metadata":[]},"innerBlocks":[],"innerHTML":"\n<p>Moreover, the frequency (color), amplitude (brightness), and polarization of the light can also be controlled, meaning that the output is in essence a designer beam.<\/p>\n<p>The researchers have already succeeded at producing a vortex beam (a helical, corkscrew-shaped stream of light) from a flat surface. They also envision flat lenses that could focus an image without aberrations.<\/p>\n<p>Yu, Capasso, and Gaburro's co-authors included Patrice Genevet, Mikhail A. Kats, Francesco Aieta, and Jean-Philippe Tetienne.<\/p>\n<p>The research was supported by the <a href=\"http:\/\/www.nsf.gov\/\">National Science Foundation<\/a> (NSF), the NSF-funded <a href=\"http:\/\/www.nsec.harvard.edu\/\">Harvard Nanoscale Science and Engineering Center<\/a>, the Center for Nanoscale Systems at Harvard (part of the NSF-funded National Nanotechnology Infrastructure Network), the European Communities Seventh Framework Programme, and the Harvard Faculty of Arts and Sciences' Science Division Research Computing Group.<\/p>\n","innerContent":["\n<p>Moreover, the frequency (color), amplitude (brightness), and polarization of the light can also be controlled, meaning that the output is in essence a designer beam.<\/p>\n<p>The researchers have already succeeded at producing a vortex beam (a helical, corkscrew-shaped stream of light) from a flat surface. They also envision flat lenses that could focus an image without aberrations.<\/p>\n<p>Yu, Capasso, and Gaburro's co-authors included Patrice Genevet, Mikhail A. Kats, Francesco Aieta, and Jean-Philippe Tetienne.<\/p>\n<p>The research was supported by the <a href=\"http:\/\/www.nsf.gov\/\">National Science Foundation<\/a> (NSF), the NSF-funded <a href=\"http:\/\/www.nsec.harvard.edu\/\">Harvard Nanoscale Science and Engineering Center<\/a>, the Center for Nanoscale Systems at Harvard (part of the NSF-funded National Nanotechnology Infrastructure Network), the European Communities Seventh Framework Programme, and the Harvard Faculty of Arts and Sciences' Science Division Research Computing Group.<\/p>\n"],"rendered":"\n<p>Moreover, the frequency (color), amplitude (brightness), and polarization of the light can also be controlled, meaning that the output is in essence a designer beam.<\/p>\n<p>The researchers have already succeeded at producing a vortex beam (a helical, corkscrew-shaped stream of light) from a flat surface. They also envision flat lenses that could focus an image without aberrations.<\/p>\n<p>Yu, Capasso, and Gaburro's co-authors included Patrice Genevet, Mikhail A. Kats, Francesco Aieta, and Jean-Philippe Tetienne.<\/p>\n<p>The research was supported by the <a href=\"http:\/\/www.nsf.gov\/\">National Science Foundation<\/a> (NSF), the NSF-funded <a href=\"http:\/\/www.nsec.harvard.edu\/\">Harvard Nanoscale Science and Engineering Center<\/a>, the Center for Nanoscale Systems at Harvard (part of the NSF-funded National Nanotechnology Infrastructure Network), the European Communities Seventh Framework Programme, and the Harvard Faculty of Arts and Sciences' Science Division Research Computing Group.<\/p>\n"}],"innerHTML":"\n<div class=\"wp-block-group alignwide\">\n\n\r\n\t\n\t\r\n\n\n<\/div>\n","innerContent":["\n<div class=\"wp-block-group alignwide\">\n\n","\r\n\t","\n\t\r\n","\n\n<\/div>\n"],"rendered":"\n<div class=\"wp-block-group alignwide has-global-padding is-content-justification-center is-layout-constrained wp-block-group-is-layout-constrained\">\n\n\n\t\t<p>Exploiting a novel technique called phase discontinuity, researchers at the Harvard <a href=\"http:\/\/www.seas.harvard.edu\/\">School of Engineering and Applied Sciences<\/a> (SEAS) have induced light rays to behave in a way that defies the centuries-old laws of reflection and refraction.<\/p>\n<p>The discovery, published Sept. 2 in the journal Science, has led to a reformulation of the mathematical laws that predict the path of a ray of light bouncing off a surface or traveling from one medium into another \u2014 for example, from air into glass.<\/p>\n<p>\"Using designer surfaces, we've created the effects of a fun-house mirror on a flat plane,\" said co-principal investigator <a href=\"http:\/\/www.seas.harvard.edu\/capasso\/\">Federico Capasso<\/a>, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS. \"Our discovery carries optics into new territory and opens the door to exciting developments in photonics technology.\"<\/p>\n<p>It has been recognized since ancient times that light travels at different speeds through different media. Reflection and refraction occur whenever light encounters a material at an angle, because one side of the beam is able to race ahead of the other. As a result, the wave front changes direction.<\/p>\n<p>The conventional laws, taught in physics classrooms worldwide, predict the angles of reflection and refraction based only on the incident (incoming) angle and the properties of the two media.<\/p>\n<p>While studying the behavior of light impinging on surfaces patterned with metallic nanostructures, the researchers realized that the usual equations were insufficient to describe the bizarre phenomena observed in the lab.<\/p>\n<p>The new generalized laws, derived and experimentally demonstrated at Harvard, take into account the Capasso group's discovery that the boundary between two media, if specially patterned, can itself behave like a third medium.<\/p>\n<p>\"Ordinarily, a surface like the surface of a pond is simply a geometric boundary between two media, air and water,\" said lead author Nanfang Yu, Ph.D. '09, a research associate in Capasso's lab at SEAS. \"But now, in this special case, the boundary becomes an active interface that can bend the light by itself.\"<\/p>\n<p>The key component is an array of tiny gold antennas etched into the surface of the silicon used in Capasso's lab. The array is structured on a scale much thinner than the wavelength of the light hitting it. This means that, unlike in a conventional optical system, the engineered boundary between the air and the silicon imparts an abrupt phase shift \u2014 dubbed \"phase discontinuity\" \u2014 to the crests of the light wave crossing it.<\/p>\n<p>Each antenna in the array is a tiny resonator that can trap the light, holding its energy for a given amount of time before releasing it. A gradient of different types of nanoscale resonators across the surface of the silicon can effectively bend the light before it even begins to propagate through the new medium.<\/p>\n<p>The resulting phenomenon breaks the old rules, creating beams of light that reflect and refract in arbitrary ways, depending on the surface pattern.<\/p>\n<p>In order to generalize the textbook laws of reflection and refraction, the Harvard researchers added a new term to the equations, representing the gradient of phase shifts imparted at the boundary. Importantly, in the absence of a surface gradient, the new laws reduce to the well-known ones.<\/p>\n<p>\"By incorporating a gradient of phase discontinuities across the interface, the laws of reflection and refraction become designer laws, and a panoply of new phenomena appear,\" said Zeno Gaburro, a visiting scholar in Capasso's group who was co-principal investigator for this work. \"The reflected beam can bounce backward instead of forward. You can create negative refraction. There is a new angle of total internal reflection.\"<\/p>\n\r\n\t\n\n\t<figure class=\"wp-block-image aligncenter size-full is-resized\"><img src=\"https:\/\/news.harvard.edu\/gazette\/wp-content\/uploads\/2011\/09\/seas-photo4.jpg\" alt=\"\" class=\"wp-image-89339\"><figcaption class=\"wp-element-caption\">Nanfang Yu, Zeno Gaburro, Federico Capasso, and colleagues at SEAS have created strange optical effects, including corkscrew-like vortex beams, by reflecting light off a flat, nanostructured surface. Image courtesy of Nanfang Yu\/SEAS\t\t\t<\/figcaption><\/figure>\n\t\n\t\r\n\n<p>Moreover, the frequency (color), amplitude (brightness), and polarization of the light can also be controlled, meaning that the output is in essence a designer beam.<\/p>\n<p>The researchers have already succeeded at producing a vortex beam (a helical, corkscrew-shaped stream of light) from a flat surface. They also envision flat lenses that could focus an image without aberrations.<\/p>\n<p>Yu, Capasso, and Gaburro's co-authors included Patrice Genevet, Mikhail A. Kats, Francesco Aieta, and Jean-Philippe Tetienne.<\/p>\n<p>The research was supported by the <a href=\"http:\/\/www.nsf.gov\/\">National Science Foundation<\/a> (NSF), the NSF-funded <a href=\"http:\/\/www.nsec.harvard.edu\/\">Harvard Nanoscale Science and Engineering Center<\/a>, the Center for Nanoscale Systems at Harvard (part of the NSF-funded National Nanotechnology Infrastructure Network), the European Communities Seventh Framework Programme, and the Harvard Faculty of Arts and Sciences' Science Division Research Computing Group.<\/p>\n\n\n<\/div>\n"}},"jetpack-related-posts":[{"id":116117,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2012\/08\/perfecting-optics\/","url_meta":{"origin":88996,"position":0},"title":"Perfecting optics","author":"harvardgazette","date":"August 27, 2012","format":false,"excerpt":"Applied physicists at the Harvard School of Engineering and Applied Sciences (SEAS) have created an ultrathin, flat lens that focuses light without imparting the distortions of conventional lenses.","rel":"","context":"In "Science & Tech"","block_context":{"text":"Science & Tech","link":"https:\/\/news.harvard.edu\/gazette\/section\/science-technology\/"},"img":{"alt_text":"","src":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/08\/lens_605mage1.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/08\/lens_605mage1.jpg?resize=350%2C200 1x, https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/08\/lens_605mage1.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":104469,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2012\/03\/building-invisibility-cloaks-starts-small\/","url_meta":{"origin":88996,"position":1},"title":"Building invisibility cloaks starts small","author":"harvardgazette","date":"March 8, 2012","format":false,"excerpt":"Working at a scale applicable to infrared light, a Harvard team has used extremely short and powerful laser pulses to create 3-D patterns of tiny silver dots within a material. Those suspended metal dots are essential for building futuristic devices like invisibility cloaks.","rel":"","context":"In "Science & Tech"","block_context":{"text":"Science & Tech","link":"https:\/\/news.harvard.edu\/gazette\/section\/science-technology\/"},"img":{"alt_text":"","src":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/03\/seas_3d_kevin-vora-sq_605.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/03\/seas_3d_kevin-vora-sq_605.jpg?resize=350%2C200 1x, https:\/\/news.harvard.edu\/wp-content\/uploads\/2012\/03\/seas_3d_kevin-vora-sq_605.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":171426,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2015\/06\/harvards-biggest-donation\/","url_meta":{"origin":88996,"position":2},"title":"Big boost for SEAS","author":"harvardgazette","date":"June 3, 2015","format":false,"excerpt":"The Harvard community celebrates John A. Paulson\u2019s $400 million gift to boost the School of Engineering and Applied Sciences, the University\u2019s largest donation ever.","rel":"","context":"In "Campus & Community"","block_context":{"text":"Campus & Community","link":"https:\/\/news.harvard.edu\/gazette\/section\/campus-community\/"},"img":{"alt_text":"","src":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_1160_605.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_1160_605.jpg?resize=350%2C200 1x, https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_1160_605.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":171390,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2015\/06\/harvard-receives-its-largest-gift\/","url_meta":{"origin":88996,"position":3},"title":"Harvard receives its largest gift","author":"harvardgazette","date":"June 3, 2015","format":false,"excerpt":"John A. Paulson gives $400 million to Harvard to endow the School of Engineering and Applied Sciences, the largest donation in the University\u2019s history.","rel":"","context":"In "Campus & Community"","block_context":{"text":"Campus & Community","link":"https:\/\/news.harvard.edu\/gazette\/section\/campus-community\/"},"img":{"alt_text":"","src":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_john_070_605.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_john_070_605.jpg?resize=350%2C200 1x, https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/06\/060315_paulson_john_070_605.jpg?resize=525%2C300 1.5x"},"classes":[]},{"id":104774,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2012\/03\/innovation-motivation-innovation-at-harvard\/","url_meta":{"origin":88996,"position":4},"title":"Innovation Motivation – Innovation at Harvard","author":"harvardgazette","date":"March 9, 2012","format":false,"excerpt":"In lecture halls, laboratories, and spaces across Harvard, dedicated teachers including Kevin Kit Parker, Gordon McKay Professor of Bioengineering and Applied Physics in the School of Engineering and Applied Sciences, are creating fertile environments for innovation, championing bold ideas and encouraging students to think in new ways.","rel":"","context":"In "Campus & Community"","block_context":{"text":"Campus & Community","link":"https:\/\/news.harvard.edu\/gazette\/section\/campus-community\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":177358,"url":"https:\/\/news.harvard.edu\/gazette\/story\/2015\/12\/harvards-federico-capasso-co-recipient-of-rumford-prize\/","url_meta":{"origin":88996,"position":5},"title":"Harvard\u2019s Federico Capasso co-recipient of Rumford Prize","author":"harvardgazette","date":"December 10, 2015","format":false,"excerpt":"Harvard physicist Federico Capasso is the co-recipient of the 2015 Rumford Prize, awarded by the American Academy of Arts and Sciences. He shares the prize with Alfred Cho in recognition of their contributions to the field of laser technology.","rel":"","context":"In "Campus & Community"","block_context":{"text":"Campus & Community","link":"https:\/\/news.harvard.edu\/gazette\/section\/campus-community\/"},"img":{"alt_text":"","src":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/12\/capasso605.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/12\/capasso605.jpg?resize=350%2C200 1x, https:\/\/news.harvard.edu\/wp-content\/uploads\/2015\/12\/capasso605.jpg?resize=525%2C300 1.5x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/posts\/88996","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/users\/105622744"}],"replies":[{"embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/comments?post=88996"}],"version-history":[{"count":1,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/posts\/88996\/revisions"}],"predecessor-version":[{"id":279649,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/posts\/88996\/revisions\/279649"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/media\/89001"}],"wp:attachment":[{"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/media?parent=88996"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/categories?post=88996"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/tags?post=88996"},{"taxonomy":"format","embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/gazette-formats?post=88996"},{"taxonomy":"series","embeddable":true,"href":"https:\/\/news.harvard.edu\/gazette\/wp-json\/wp\/v2\/series?post=88996"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}