Optical amplifiers enhance light signals similarly to how audio amplifiers boost sound. However, conventional compact models often require substantial power, limiting their effectiveness. A groundbreaking device developed at Stanford University, published in the journal Nature, addresses this limitation by efficiently reusing much of the energy necessary for its operation.
Amir Safavi-Naeini, the senior author of the study and an associate professor of physics at Stanford's School of Humanities and Sciences, stated, "We've demonstrated, for the first time, a truly versatile, low-power optical amplifier, one that can operate across the optical spectrum and is efficient enough that it can be integrated on a chip." This advancement enables the construction of more sophisticated optical systems than previously achievable.
The new amplifier can elevate the intensity of a light signal by approximately 100 times while consuming only a few hundred milliwatts of power--significantly less than traditional devices. Its compact and efficient design allows it to operate on battery power, paving the way for integration into everyday electronics like laptops and smartphones.
Minimized Noise and Expanded Bandwidth
Like audio amplifiers, optical amplifiers can introduce noise during the signal boosting process. However, researchers have designed this new model to minimize noise while operating across a broader range of wavelengths, facilitating the transmission of more data with reduced interference.
This advanced amplifier utilizes energy stored in a light beam, functioning as a "pump." Its efficiency hinges on the intensity of this pump light.
Devin Dean, co-first author and a doctoral student in Safavi-Naeini's lab, explained, "By recycling the energy of the pump that powers this amplifier, we made it more efficient, and this doesn't come at a cost to its other properties." This innovative design employs a resonant approach akin to techniques used in lasers, allowing the system to enhance light strength over time by reflecting it back on itself, much like light bouncing between mirrors.
Within the amplifier, the pump light is generated in a resonator, where it circulates continuously, akin to a racetrack. As it loops, the light intensity increases, enabling more effective amplification of the target signal. This method results in stronger output with lower energy input.
Due to its compact and energy-efficient nature, this device could function on battery power, making it suitable for small electronic devices.
"When you can do that, then the possibilities are really quite broad because they are so small that you can mass produce them and power them with batteries," Dean noted. "They could be used potentially for data communications, biosensing, making new light sources, or a host of different things."
Broad Applications and Research Backing
Additional co-authors from Stanford include Taewon Park, Martin Fejer, Hubert Stokowski, and several doctoral students. The team is also pursuing a patent for methods that achieve quantum advantage in power-constrained photonic sensors. This research received support from the Defense Advanced Research Projects Agency, NTT Research, and the National Science Foundation.