Recently, a group of researchers from the School of Engineering and Applied Sciences of Yale University in the United States has developed a groundbreaking "anti-laser" system that can guide light and other electromagnetic waves for signal processing without any unnecessary signal reflection. This innovation can promote local area networks, photonics and other applications. The relevant research results were recently published in the journal Science Advances.
The team leader, A. Douglas Stone, led another team more than 10 years ago to create "anti laser" or "coherent perfect absorber" (CPA). Anti-laser does not emit beam like laser, but absorbs input light with the same accuracy.
In a laser, light is reflected back and forth between two mirrors, and each time it will be amplified by an amplification material called "gain medium". In ordinary scattering light sources, atoms radiate independently and produce many different wavelengths of light, so light will spread in multiple directions. However, in a laser, atoms radiate at the same frequency and direction, resulting in a concentrated beam of a single wavelength.
The anti-laser uses not amplification material, but a material that absorbs light (i.e. "loss medium"). In its simplest version, the anti-laser will divide a laser beam into two beams and guide the two beams to meet on a paper-thin silicon chip. Then, the light waves are precisely tuned, "locked" with each other and captured, and then dissipated and converted into heat.
Based on this concept, researchers developed a device based on the "non-reflective scattering mode" (RSM). Instead of absorbing sound waves, this device redirects them to specific channels.
With optical fiber and modern photonic circuits, it is very valuable to guide light without any light reflecting back. This device eliminates a major obstacle faced by signal routers - signal reflection, which is exactly the key component of modern nano-photon and RF networks.
Next, researchers plan to build a similar device with negligible absorption, so that all energy can be effectively guided to play its information transmission or sensing function.
Source: OFweek
