Efficient 2.7- μm Difference Frequency Generation Using Direct-Bonded Quasi-Phase-Matched LiNbO_3 Ridge Waveguide and Investigation of O-H Absorption Influence

摘要

We fabricated direct-bonded quasi-phase-matched (QPM) LiNbO_3 (LN) ridge waveguides for difference frequency generation (DFG) in the 2.7-μm wavelength range, and obtained a conversion efficiency of 87%/W. We showed that dips in the DFG tuning curve originated from the absorption of H_2O in air and the O-H absorption in the LN crystal exhibited no influence on DFG when we used the type-0 phase-matching condition. We confirmed that the direct-bonded QPM-LN ridge waveguide is suitable for achieving high-efficiency DFG in the 2.7-μm range.