Noncritically Phase-Matched Self-Difference Frequency Generation Using Transition-Metal Doped Chalcogenides

We revisit self-difference frequency generation –– nonlinear mixing of the lasing field induced by stimulated emission with its pump source in a laser gain medium –– by employing transition-metal doped chalcogenides along with the standard birefringent phase-matching techniques for mid-infrared applications. The use of an a-cut Cr:CdSe crystal under the noncritical PM condition has significantly improved the conversion efficiency compared to the previous results obtained in a Cr:ZnSe slab with Fresnel phase-matching. To generalize the self-mixing design, the phase-matching conditions of solid solutions CdSxSe1-x doped with Cr2+ and Fe2+ ions are characterized in the mid-infrared spectral range.