Recently, in a paper published in "Natural Photonics", researchers at the University of California, Santa Barbara described a method to promote LED display and lighting technology, from VR headsets to automotive lighting, all kinds of LED equipment are Can become more precise and smooth.

Jonathan Schuller, a professor of electrical and computer engineering at the University of California, Santa Barbara, said: "We are showing a new type of photon structure that not only allows you to extract more photons, but also directs them to where you want them. "He explained that external packaging components are generally used to control the light emitted by LEDs, and our improved performance is achieved without using external packaging components."

The light in the LED is generated in the semiconductor material. When the negatively charged electrons moving along the semiconductor lattice meet the positively charged holes (no electrons) and change to a lower energy state, in this process Will emit a photon. During their measurement, the researchers found that a considerable number of photons were being produced, but none of them were produced in LEDs.

"We realized that if you look at the angular distribution of emitted photons before forming a pattern, it tends to peak in a specific direction, which is usually trapped in the LED structure," Schuller said. "So we realized that traditional supersurface concepts can be used to design light that is usually trapped."

The design they decided included embedding a 1.45-micron-long array of gallium nitride (GaN) nanorods on a sapphire substrate, in which quantum traps of indium gallium nitride were embedded to limit electrons and holes to emit light. In addition to allowing more light to leave the semiconductor structure, the polarization of light is generated in this process, which plays a very important role in many applications.

The researchers said that the metasurface is essentially a sub-wavelength antenna array. On the other hand, the LED emits self-illumination instead of stimulated coherent light based on laser. Photon trap spontaneous emission samples all possible photon motions, so light looks like a beam of photons moving in all possible directions. The question is whether they can guide the generated photons in the desired direction through careful nanoscale design and semiconductor surface fabrication.

Gallium nitride is very difficult to handle and requires a special process to manufacture high-quality crystals. Finally, the team designed and fabricated a semiconductor surface using the University of California Santa Barbara nano-fabrication equipment to adapt to the super-surface concept of self-luminous emission.