Anti-mirror optical illusion could increase LED luminosity and laser power

November 15, 2010 By Lisa Zyga, feature
(a) In the mirror effect, an object placed in front of a mirror is equivalent to two identical objects. (b) In the anti-mirror effect, two identical perfect electrical conductors (PECs) on both sides of a perfect lens are equivalent to one object. Image credit: Yadong Xu, et al.

( -- By making multiple objects appear to look like only one using a "perfect lens," scientists have demonstrated a new optical illusion that could have practical applications in lighting systems. Normally, a mirror makes one object appear to look like two objects (the original object and its reflection). Since the new set-up does the opposite, the scientists have called the concept the "anti-mirror effect."

Huanyang Chen, a researcher in and optics from Soochow University in Jiangsu, China, and his colleagues have discovered and modeled the anti-mirror effect. The ability to make multiple objects look like one using “overlapped illusion optics” has not been found in nature before now.

To demonstrate the basic idea, the researchers explained that two identical cylindrical perfect electric conductors (PECs) are placed on opposite sides of a perfect lens made of a negative refractive index material. When viewed from the far field (beyond a certain distance) on either side of the lens, the two PECs look like one. Further, when the scientists replaced one of the circular PECs with an illusion device with an elliptic cylindrical PEC, both PECs look like only one circular cylindrical PEC.

Further elaborating on this effect, the researchers showed that illusion devices with elliptic cylindrical PECs can be used in place of both real cylindrical PECs. Once again, the two illusion devices look like one PEC. As the scientists explained, this effect occurs because the two illusion devices are close enough together so that their virtual illusion spaces overlap. Inside this shared region, both illusion devices form a single PEC image.

“The two PECs on both sides of the perfect lens follow the image-forming principle so that each of them is overlapped with the virtual image of another,” Chen explained to “The anti-mirror effect stems from the evanescent wave amplification of the perfect lens.”

The anti-mirror effect could have applications in both solid-state lighting, such as LEDs, and in coherent light sources, such as lasers. Currently, one of the biggest challenges in LED development is achieving a high enough luminosity for general lighting purposes. One method of increasing LED illuminance is to package many LEDs inside a single bulb; however, the problem is that the lamp's spatial illumination is not uniform. Using the new overlapped illusion optics, the researchers show that the images from multiple LEDs in different places can be overlapped to make the bulb look like a single-LED source with high, uniform illumination.

The proposed overlapped illusion optics method could also increase the power and preserve the spatial uniformity of lasers. Usually, spatial uniformity degrades when two coherent sources are aligned due to interference. Using the same configuration as the LEDs, multiple coherent sources can be operated at the same frequency and phase to double the light amplitude and quadruple the total power of the coherent system. These improvements cannot be achieved using traditional beam-combining techniques.

“Our current work is just a conceptual model,” Chen said. “We have recently realized the first illusion device – an “invisible gateway” – by using a transmission-line medium.” See .

Explore further: Invisibility cloak that generates virtual images gets closer to realization

More information: Yadong Xu, et al. “Anti-mirror effect: A perfect lens brings a brighter future.” arXiv:1011.0542v1 [physics.optics]


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5 / 5 (2) Nov 15, 2010
totally sweet, i see fast coding/decoding applications for fibre optic networks and entangled beams as qubits for quantum computing as well, but it wouldn't surprise if nature invented it already, somewhere down the road they will find a bird, a shrimp or some nocturnal animal that uses this to enhance its vision
not rated yet Nov 15, 2010
I wonder what happens if these two lasers used in this setup are not driven in same phase? Or maybe one could use lasers with different colors (frequencies). How would that appear? Or would it work to replace one of those light sources with detector? Would the transmitted light interfere with the received one or would they both be perfectly focusable to same cable?
not rated yet Nov 18, 2010
This could be used to combine colors for better displays as well. I think this technology is only a bit of a help for LEDs. I think a big breakthrough in LED technology would be a package with a gradiating refractive index from silicon to air. Since most of the light in an LED is lost when the photon tries to move from the silicon to the, usually plastic, package, due to the large difference in the refractive index of the two materials. This would also increase LED life time as well since most LEDs go bad because of the heat generated by the photons being absorbed.
not rated yet Nov 18, 2010
Multiple wavelengths are still problematic for illusion optics and optical metamaterials in general, so combining colors is a ways off.

The illusion effects described are created by independently manipulating the electric and magnetic aspects of light. These aspects are wavelength dependent and structures that can affect these aspects must currently be sized accordingly. Multi-wavelength metamaterials are one of the holy grails of transformation optics.
not rated yet Dec 05, 2010
"but it wouldn't surprise if nature invented it already, somewhere down the road they will find a bird, a shrimp or some nocturnal animal that uses this to enhance its vision"

Anything like tapeturn lucidum?
not rated yet Dec 06, 2010
totally sweet, i see fast coding/decoding applications for fibre optic networks and entangled beams as qubits for quantum computing as well, but it wouldn't surprise if nature invented it already, somewhere down the road they will find a bird, a shrimp or some nocturnal animal that uses this to enhance its vision

Think even more simply: supercheap lighting. Using anti-mirror, LED bulbs can use larger or more varied LEDs and put out a single light sounce as opposed to that spotty garbage you typically get.
not rated yet Jan 01, 2011
"Anything like tapeturn lucidum?"

Sorry, its nothing like that. tapeturn lucidum is a reflective mechanism, and although the effect mentioned is called the anti-mirror effect, its not achieved through reflection, but through the use of materials that exhibit a negative index of refraction, which to my knowledge no species has come close to manufacturing.

Eyes are hugely complicated to begin with, being the product of an evolutionary arms war for millions of years with the end result being those that don't see well, don't hunt well, and therefor die. Considering our eyes have been under the stress of survival for nearly the entire existence of our species, and all other large species, its reasonable to assume that our eyes are already the product of hyper evolution, and that negative index refraction may in fact be so complicated, that it becomes unlikely for a simple process like evolution to stumble upon.

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