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  • Exciting excitons

     Japo_Japo updated 1 month ago 1 Member · 1 Post
  • Japo_Japo

    September 10, 2021 at 3:06 am

    Kim’s polariton laser, however, pairs electrons with so-called “holes” to form another type of particle, an exciton. A hole is a gap where an electron could exist in a structure and is treated by physicists as a real, separate particle.

    These excitons are bosons, and an unlimited number of them can inhabit any given energy level. Using bosons in lasers has been a scientific goal for decades, but Yamamoto’s team is the first to successfully build an electrically driven laser using bosons. (The result was recently reproduced and confirmed by scientists at the University of Michigan

    This change drastically reduces the amount of power required to run the laser. The current iteration of the polariton laser requires two to five times less energy than a comparable conventional laser, but could require 100 times less energy in the future.

    “The outcome would look similar to that of the traditional photon lasers, but the physical mechanisms inside are very different,” Kim said.

    The laser consists of an electron reservoir and a hole reservoir. When a current is applied, electrons and holes come together to form excitons in excited energy levels. When a photon hits an exciton, it forms a polariton and emits an identical photon.

    The entire process is like a solar cell in reverse, Kim says.

    “In a solar cell, you use light to form excitons and separate them into an electron and a hole electrically,” she said. “We bring together an electron and a hole electrically to emit light.”

    One benefit of the electrically driven polariton laser is it only needs to be attached to a power supply to emit photons, allowing it to be easily integrated with existing semiconductor chips in the future

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