UCSB physicists mix two lasers to create light at many frequencies
A team of physicists at UC Santa Barbara has seen the light, and it comes in many different colors. By aiming high- and low-frequency laser beams at a semiconductor, the researchers caused electrons to be ripped from their cores, accelerated and then smashed back into the cores they left behind. This recollision produced multiple frequencies of light simultaneously. Their findings appear in the current issue of the science journal Nature. When the high-frequency optical laser beam hits the semiconductor material -- in this case, gallium arsenide nanostructures -- it creates an electron-hole pair called an exciton. The electron is negatively charged, and the hole is positively charged, and the two are bound together by their mutual attraction. The electron has excess energy because it has been accelerated, and when it slams back into the hole, the recombined electron-hole pair emits photons at new frequencies. In terms of real-world applications, the electron-hole recollision phenomenon has the potential to significantly increase the speed of data transfer and communication processes.