Compact continuous-wave mid-infrared generation via a shared-cavity Nd:YVO 4 /PPMgLN OPO with laser-diode pumping

Compact mid-infrared laser generation is achieved using a demonstrated shared-cavity optical parametric oscillator (OPO) based on periodically poled magnesium-doped lithium niobate (PPMgLN). The shared-cavity design co-resonates the 1064 nm fundamental light and the ~1.5 μm signal wave within a single optical cavity, thereby ensuring good spatial mode overlap and intracavity power enhancement. This configuration substantially lowers the oscillation threshold and enhances the overall conversion efficiency. The oscillation threshold at 807.6 nm is only 0.9 W. Under stable operation at a 5.0 W pump power, the system generates output at 1472.9 nm (signal) and 3833.2 nm (idler), with respective output powers of 430 mW and 187 mW. Signal linewidth is 0.9 nm, while the idler linewidth is relatively wide, 6.4 nm. The generated 3.8 μm mid-infrared laser falls within the molecular “fingerprint” region – making it highly valuable for high-sensitivity spectral analysis and trace-gas sensing – while the 1.5 μm signal wavelength lies within the low-loss telecommunications window.