Tunable multi-wavelength active conversion of 1550 nm signals in a Cr3+:LiCAF — PPSLT laser

This paper demonstrates an intra-cavity tunable and multiple wavelength conversion for optical communications in the third spectral window based on single-pass difference frequency generation (DFG) with intracavity PPSLT crystals. The experimental setup is based on single-pass difference frequency generation with a PPSLT crystal placed inside the V-folded cavity of a tunable self-injection-locked diode-pumped Cr³⁺:LiCAF, which oscillates around 792±8 nm with a spectral width lower than 1 nm. Thus, the spectral allocation of the converted spectrum can be tuned through the coupled cavity based on a diffraction grating (Littrow mounting) thanks to the spectral characteristics of the Cr³⁺:LiCAF. Despite the very limited experimental conditions available to us with the laser operating only 1.5 times above threshold with a modest intra-cavity power, it is shown that improving the laser design to approach the high conversion efficiency, even in excess of 100% if the laser is carefully designed so that conditions to achieve parametric net gain are fulfilled.