Metasurface Design Methods Can Make LED Light Act More Like Lasers

Light-emitting diodes (LEDs) are not exactly new technology, but their use over time has evolved from rather dim replacements of incandescent signal lights in control panels to today’s home lighting. Although LEDs have the reputation of being power-efficient, there is still a lot of efficiency to be gained.

UC Santa Barbara researchers [Jonathan Schuller] and his team found that a large number of the photons that are generated never make it out of the LED. This means that the power that was used to generate these photons was essentially wasted. Ideally one would be able to have every single photon successfully make it out of the LED to contribute to the task of illuminating things.

In their paper titled ‘Unidirectional luminescence from InGaN/GaN quantum-well metasurfaces‘  (pre-publication Arxiv version) they describe the problem of photon emission in LEDs. Photons are normally radiated in all directions, causing a ‘spray’ of photons that can be guided somewhat by the LED’s packaging and other parameters. The challenge was thus to start at the beginning, having the LED emit as many photons in one direction as possible.

Their solution was the use of a metasurface-based design, consisting out of gallium nitride (GaN) nanorods on a sapphire substrate. These were embedded with indium gallium nitride (InGaN) quantum wells which emit the actual photons. According to one of the researchers, the idea is based on subwavelength antenna arrays already used with coherent light sources like lasers.

With experiments showing the simulated improvements, it seems that this research may lead to even brighter, more efficient LEDs before long if these findings translate to mass production.

(Thanks, Qes)

33 thoughts on “Metasurface Design Methods Can Make LED Light Act More Like Lasers

    1. Why is everybody so concerned with brighter LEDs? Don’t you realize that this means less heat per lumen? Heat is a serious problem for LED lighting, because it reduces life and realiability.

      And btw, more maximum brightness is not a bad thing either.

  1. “before long if these findings translate to mass production.”

    I’d be curious how much this improved design costs, both in raw materials and manufacturing equipment. If it makes the LED 5% brighter at 500% the manufacturing cost I don’t expect rapid adoption of the technology. It’s still super cool but I’m going to guess some of this is rather expensive to make seeing as they just did simulations.

    1. On the other hand if it’s the same brightness for even 10-15% less energy I can see battery powered devices using these for things like LCD backlights as long as the costs aren’t in the “dollar per LED” range.

        1. The first blue LEDs I used were in the $25 per LED range. IIRC, Volkswagen was a key reason for the price declining because under EU regulations, automobiles had to have a blue light for something in particular and VW wanted to use all LEDs instead of bulbs.

    1. Yes but the neutrinos made at the same time leave immediately as matter hardly interacts with them at all so their flux levels tell you in advance what the sun is going to do luminosity wise in the far future. Handy that, having 100k years warning of the sun changing enough to cause harm to life on Earth.

  2. Make it large enough and you have a photon drive for a space ship because light has inertia and “photon recoil” really is a thing. In the meantime we will have even more unreasonably bright blue LEDs to destroy our night vision with, yay I am so thrilled I may just go and scatter lego on the floor and have a little dance.

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