On-chip integrated mid-infrared lasers have emerged as a significant developmental direction in the field of mid-infrared lasers in recent years, attributed to their compact footprint, low energy consumption, and high conversion efficiency. In particular, on-chip integrated mid-infrared lasers based on nonlinear frequency conversion have garnered considerable attention from researchers due to their capabilities for ultra-short pulse output and broadband tunability. Notably, the advantageous physical property that the second-order nonlinear effects of materials vastly exceed their third-order nonlinear responses endows on-chip integrated mid-infrared lasers based on second-order nonlinear frequency conversion with numerous benefits, including straightforward design, high conversion efficiency, and low threshold levels. However, the current limitations in micro-nano fabrication techniques have resulted in a lack of reports on high-efficiency long-wave infrared lasers utilizing waveguide platforms of this type, specifically quasi-phase-matched crystal waveguides. Consequently, there is an urgent need to explore and develop new χ⁽²⁾ waveguide platforms to facilitate the generation of high-efficiency, broadly tunable long-wave infrared lasers. Furthermore, this experiment involved a detailed assessment of the transmission loss of the designed ZnGeP₂ waveguide, which features a phase-matching angle of 48.4º, and successfully generated long-wave infrared laser output through optical difference frequency generation.Distinct loss measurement systems were established based on the principles of the Fabry-Pérot (F-P) cavity method and the truncation method (Fig.2-Fig.3) to conduct comprehensive assessments of the transmission loss of the designed ZnGeP2 waveguide, which possesses a phase-matching angle of 48.4º. Building upon these measurements, an experimental setup for optical difference frequency generation was developed utilizing two tunable optical parametric amplifier (OPA) sources as the pump and signal light (Fig.4). The wavelengths of the pump and signal lights were adjusted to achieve broadband tunable long-wave infrared laser output. Finally, the phase-matching curve for the ZnGeP₂ waveguide corresponding to the phase-matching angle of 48.4º was calculated using the Sellmeier equation for the ZnGeP₂ crystal, facilitating the validation of the optical difference frequency generation experiments.The characterization of the waveguide's surface profile and roughness (Fig.1) confirms the quality of the waveguide fabrication. The results from loss tests conducted using both the Fabry-Pérot (F-P) cavity method and the truncation method indicate that the transmission losses for the ZnGeP₂ (ZGP) waveguide are 0.173 1 dB/cm and 0.199 8 dB/cm for the transverse electric (TE) and transverse magnetic (TM) modes, respectively, at a wavelength of 1.55 μm. Additionally, the TE mode transmission loss at 2.4 μm is recorded as 0.8 dB/cm. These findings demonstrate the excellent mode transmission capability of the ZGP waveguide in the 1.55 μm wavelength range, thereby establishing a foundation for subsequent mid-infrared laser generation based on near-infrared laser pumping and ZGP waveguides. Under these transmission loss conditions, the optical difference frequency generation experiments with the ZGP waveguide achieved tunable idle frequency output within the wavelength range of 7 to 10 μm (Fig.4). This output range encompasses typical values derived from the phase-matching curve calculated using the Sellmeier equation for pump wavelengths of 2.4 µm, 2.45 µm, and 2.5 µm (Fig.5). These results indicate the exceptional capabilities of the designed ZGP waveguide in parametric conversion applications.A micron ridge waveguide platform based on ZnGeP₂ with robust transmission characteristics has been designed. The low transmission losses observed at wavelengths of 1.5 μm and 2.4 μm fulfill the transmission requirements for on-chip integrated mid-infrared lasers. Furthermore, exploiting the excellent transparency window of ZnGeP₂ in the mid-infrared spectrum, the experiments conducted on this waveguide platform successfully achieved optical difference frequency generation, resulting in idle frequency output that is efficiently tunable across the range of 7 to 10 μm. The findings related to this ZGP waveguide provide significant reference value for the development of integrated mid-infrared lasers utilizing birefringent crystal technology.