Intracavity pumping of Yb: S-FAP and second harmonic generation for laser emission at 492.5 nm
Oxxius 492.5 nm blue-green laser sources today
Presented at the 3rd EPS-QEOD Europhoton Conference in 2008, this paper explores 492.5 nm laser emission via Yb:SFAP second harmonic generation through intracavity pumping — an approach that complements the sum-frequency mixing architectures developed in parallel Oxxius publications at the same wavelength. Where the 2006 CLEO paper demonstrated 492 nm via sum-frequency mixing of 912 nm and 1064 nm beams in a BiBO crystal, this Europhoton contribution investigates the use of Yb:S-FAP as an alternative gain medium, exploiting its three-level transition at 985 nm and the subsequent frequency doubling to reach the blue-green range.
The Yb:S-FAP intracavity pumping scheme is particularly interesting because it leverages the strong 914 nm absorption of Nd:YVO₄ to pump a co-located Yb:S-FAP crystal within the same cavity — generating 985 nm emission that can then be frequency-doubled to 492.5 nm in a single, compact assembly. This architecture was first demonstrated in the companion Optics Letters 2008 paper, which reported 120 mW at 492.5 nm and 1.4 W at 985 nm from a single 808 nm pump diode.
Why 492.5 nm matters for life science
The 492.5 nm wavelength sits between the standard 488 nm argon line and the 495 nm absorption peak of GFP and related fluorophores, making it a spectrally precise excitation source for fluorescence microscopy and flow cytometry. In applications where the 488 nm line produces too much autofluorescence background, or where fine spectral discrimination between closely spaced fluorophores is required, a source at 492.5 nm provides a meaningful alternative. Oxxius’s broader expertise in intracavity nonlinear frequency conversion, reflected across multiple publications at this wavelength, underpins the CW & Modulated Laser product line covering the blue-green spectral range.
Abstract
Intracavity pumping of Yb:S-FAP and second harmonic generation for laser emission at 492.5 nm