Lasers solides à base de transitions 3 niveaux du néodyme et de l’ytterbium, émission dans le bleu

Solid-state lasers based on three-level transitions of neodymium and ytterbium, blue emission

Oxxius blue DPSS laser sources today

Presented at the CMDO+ “Lasers Solides Visibles UV” thematic workshop in 2008, this contribution by Balembois, Castaing, and Georges reviews three-level Nd and Yb solid-state laser transitions as routes to blue emission — covering both the physics of quasi-three-level operation and the practical design strategies that make these transitions viable in compact, diode-pumped architectures.

Three-level laser transitions are inherently more challenging than the four-level transitions that dominate most commercial DPSS lasers. In a three-level system, the lower laser level is thermally populated at room temperature, creating a reabsorption loss that must be overcome before threshold can be reached. For neodymium, the relevant transitions are at 914 nm (Nd:YVO₄) and 912 nm (Nd:GdVO₄) — both quasi-three-level lines that, when frequency-doubled, yield blue output at 457 nm and 456 nm respectively, or when combined via sum-frequency mixing with the standard 1064 nm line, yield emission at 491–492 nm. For ytterbium, the three-level transition near 981–985 nm (Yb:SFAP, Yb:KYW) provides an alternative route to blue-green output via second-harmonic generation.

From workshop research to production lasers

The design principles discussed in this workshop contribution — thermal management of the gain medium, intracavity pump field enhancement, and mode matching — are the same principles that Oxxius has since applied in its production laser portfolio. The 473 nm LBX and 491–492 nm sources currently offered by Oxxius trace their lineage directly to this body of research on three-level Nd and Yb transitions, demonstrating that fundamental laser physics work at the workshop level can translate into reliable, OEM-ready products.