Comparison of back conversion and power differential in extra-cavity multi-optical parametric oscillator using MgO:APLN

The extra-cavity multi-optical parametric oscillator (MOPO) using MgO-doped aperiodically poled lithium nio-bite (MgO:APLN) is a technique to generate multi-wavelength tunable laser output, in which the back conversion and power differential can reduce the output power and conversion efficiency. A comparison of the back con -version and power differential between the two methods is presented in this paper. One approach is to adjust the mirror transmittance to change the parametric light's power density involved in the oscillation. With 1.47 mu m transmittance of 20 % and 3.30 mu m transmittance of 60 %, the 3.30 mu m output power is 0.95 W, the 3.84 mu m output power is 0.94 W, and the power ratio is 1.01. The other approach is to add two electro-optical polarization mode converters (EO PC) to change the parametric light's polarization. When the electric fields of two EO PCs are 66 V/mm and 15 V/mm, the 3.30 mu m and 3.84 mu m output powers are 2.54 W and 2.49 W, the conversion ef-ficiencies are 10.3 % and 10.0 %, and the power ratio is 1.02. The comparison results confirm that both methods have the capability of back conversion suppression and power differential reduction. Compared with the adjusting transmittance, adding EO PCs has higher output power and conversion efficiency, which is the first reported method for better balanced multi-wavelength laser output.