Efficient and wavelength-tunable second-harmonic generation toward the green gap.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40601739.
- Also identified by DOI 10.1126/sciadv.adw2781 and PMC identifier 12219504.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Achieving compact and efficient visible laser sources is crucial for a wide range of applications. However, traditional semiconductor laser technology faces difficulties in producing high-brightness green light, leaving a "green gap" in wavelength coverage. Second-harmonic generation (SHG) offers a promising alternative by converting near-infrared sources to visible wavelengths with high efficiency and spectral purity. Here, we demonstrate efficient and tunable SHG within the green spectrum using a high-<i>Q</i> Si<sub>3</sub>N<sub>4</sub> microresonator. On-chip green power as high as 5.3 milliwatts is generated with a conversion efficiency of 141% per watt (absolute 7.9%). A space-charge grating induced by the photogalvanic effect realizes reconfigurable grating numbers and flexible wavelength tuning over a range of 2.6 terahertz. In addition, grating formation dynamics and competition are observed. These findings underscore the potential of Si<sub>3</sub>N<sub>4</sub> as a robust, integrative platform for on-chip, tunable green light sources.