This miniature optical amplifier amplifies light up to 100 times and can be integrated into smartphones.

Light is the foundation of many modern technologies, from TV and satellites to fiber optic cables that transmit internet data across continents. Recently, a team of physicists at Stanford University has developed a new approach that will help light-based systems advance even further.

 

This tiny optical amplifier – about the size of a fingertip – operates with extremely low power consumption while maintaining full bandwidth performance.

Similar to how audio amplifiers amplify signal volume, optical amplifiers are designed to amplify light intensity. However, many current small-scale amplifiers require a significant amount of power to operate. A new device published in the journal Nature overcomes this limitation by reusing much of the energy supplied to it, thereby significantly improving efficiency.

Amir Safavi-Naeini, the study's lead author and associate professor of physics at Stanford's School of Humanities and Sciences, said this is the first time the research team has demonstrated an optical amplifier that is both versatile and low-power, capable of operating across the entire optical spectrum and efficient enough to be integrated directly onto a chip. This opens up the possibility of building far more complex optical systems than before.

 

High performance, can be integrated onto a chip.

The amplifier developed by Stanford can boost light intensity by about 100 times but consumes only a few hundred milliwatts of power—significantly less than comparable devices of similar size. Thanks to this combination of powerful performance and a compact design, the device could even run on batteries and be integrated into laptops or smartphones in the future.

A common problem with signal amplification is interference, which can degrade data transmission quality. However, the research team showed that their device keeps additional interference to a minimum. At the same time, it supports a wider bandwidth than current small-scale amplifiers, allowing for the handling of a broader range of light frequencies. These two factors combined increase data transmission capacity and reduce interference.

The device operates based on energy stored in a beam of light called a 'pump'. The amplification efficiency depends on the intensity of this pump beam.

Resonance design and energy recycling mechanism

Devin Dean, co-lead author of the study and a graduate student in the Safavi-Naeini lab, said the team improved performance by 'recycling' the pump beam's energy without affecting other device characteristics.

To achieve this, they use a resonant structure similar to that designed in lasers as a 'energy recycling trick'. In such systems, light reflects back to itself, causing its intensity to increase – similar to when light bounces back and forth between two mirrors.

In the new amplifier, the pump light is generated inside a resonator, where it circulates in a track-like trajectory. As it continuously rotates, the light intensity gradually increases, thereby amplifying the target signal more effectively. By generating high intensity from low input energy levels, the system achieves superior performance.

Thanks to its low power consumption and ultra-compact size, this amplifier can run on batteries and be integrated into small devices such as smartphones.

According to Dean, once the technology reaches the point where it can be mass-produced and powered by batteries, the range of applications will be extremely broad. It could be used in data communication, biosensors, the development of new light sources, or many other fields that were previously impossible.