ETH-Zurich physicists have developed a new kind of laser that shatters the boundaries of possibility: it is by far the smallest electrically pumped laser in the world and one day could revolutionize chip technology.
It took a good one and a half years from the idea to its inception; a time when Christoph Walther, a PhD student in the Quantum Optoelectronics Group at ETH Zurich, spent days and nights in the FIRST lab. This was because ETH Zurich’s state-of-the-art clean-room facility provided him with the ideal conditions to set a new record in laser technology: the physicist teamed up with four colleagues and developed the smallest electrically pumped laser in the world to date.
Much smaller than the wavelength
It’s 30 micrometers long — that’s 30 millionths of a meter — eight micrometers high and has a wavelength of 200 micrometers. This makes the laser considerably smaller than the wavelength of the light it emits — a scientific first. After all, lasers normally can’t be smaller than their wavelength, the reason being that in conventional lasers light waves cause an optic resonator to oscillate — much like acoustic waves do to the soundbox of a guitar. In doing so, the light waves basically “travel” back and forth between two mirrors. The principle only works if the mirrors are larger than the wavelength of the laser. Consequently, normal lasers are limited in terms of their size.
Other researchers have endeavored to push the boundaries; “But by developing a completely new laser concept we were able to go quite a way below the limit,” says Christoph Walther.