Design of Rectangular Transmission Gratings Fabricated in LiNbO₃ for High-Power Terahertz-Wave Generation

Precise parameters are investigated for rectangular transmission gratings fabricated in a LiNbO 3 substrate for high-power terahertz-wave generation. Here, a simple setup is considered, where the pumping laser is injected into the grating surface from air or fused silica. The maximum diffraction efficiencies are 0.4 for air and 0.9 for fused silica. The designed gratings have deep grooves with a depth of about 0.5 µm and a width of 0.12–0.14 µm. It was found that the diffraction efficiency is much less sensitive to the groove depth than to the groove width.