UC Santa Barbara researchers have developed a breakthrough in laser technology: a compact, chip-scale laser that matches or exceeds the performance of much larger laboratory systems while being significantly more affordable. Led by Professor Daniel Blumenthal, the team created a matchbox-sized device that operates at 780 nm wavelength and uses rubidium atoms as a reference.
The innovation lies in how they managed to miniaturize the complex components typically found in bulky tabletop laser systems. The researchers combined a commercial Fabry-Perot laser diode with ultra-low-loss waveguides and high-quality resonators, all integrated onto a silicon nitride platform. This integration achieves remarkably low linewidth values, indicating exceptional stability and noise reduction.
The laser’s performance is particularly notable because it achieves sub-Hz fundamental linewidth and sub-KHz integral linewidth, outperforming previous integrated lasers by four orders of magnitude in key metrics. This level of precision is crucial for applications requiring ultra-stable light sources. The cost-effectiveness is also remarkable, using a $50 diode and employing CMOS-compatible wafer scale processing borrowed from electronic chip fabrication.
The technology’s practical applications are extensive. In quantum computing, it can be used for controlling neutral atoms and trapped ions. In sensing applications, it enables precise atomic clocks and gravimeters. Perhaps most intriguingly, these compact lasers could be deployed on satellites for creating detailed gravitational maps of Earth, measuring sea level changes, monitoring sea ice, and detecting earthquakes through gravitational field variations.
The key to the system’s effectiveness is its use of rubidium atoms, chosen for their well-understood properties and stable D2 optical transition. By passing the laser through rubidium vapor, the laser becomes “lassoed” to the atomic transition line, essentially adopting the stability characteristics of the atomic transition itself. This process helps eliminate unwanted frequencies or “noise” from the laser output, resulting in the pure, single-frequency light needed for precision applications.
This development represents a significant step toward making advanced quantum and sensing technologies more portable and accessible. The combination of high performance, small size, low power consumption, and cost-effectiveness makes this technology particularly suitable for field deployment and space-based applications, potentially revolutionizing how we conduct precise measurements and sensing operations outside traditional laboratory settings.
Reference: “Sub-Hz fundamental, sub-kHz integral linewidth self-injection locked 780 nm hybrid integrated laser” by Andrei Isichenko, Andrew S. Hunter, Debapam Bose, Nitesh Chauhan, Meiting Song, Kaikai Liu, Mark W. Harrington and Daniel J. Blumenthal, 18 November 2024, Scientific Reports. DOI: 10.1038/s41598-024-76699-x
