Low-threshold dual-wavelength CW mid-IR laser from shared intracavity quasi-phase-matched OPO

A low-threshold continuous wave dual-wavelength mid-infrared laser is demonstrated by using an intracavity optical parametric oscillator (OPO) with a dual-wavelength pump wave. To realize a high-quality dual-wavelength pump wave, a composite Nd:YVO₄/Nd:GdVO₄ gain medium is applied for a linear polarized state and synchronization output. With the quasi-phase-matching OPO process, it is found that the dual-wavelength pump wave shares equal signal wave oscillation and leads to a lower OPO threshold. Finally, a diode threshold pumped power of barely 2 W can be achieved for the balanced intensity dual-wavelength watt-level mid-IR laser.