Forward and backward THz-wave difference frequency generations from a rectangular nonlinear waveguide

Institute of Photonics Technologies, Department of Electrical Engineering, National Tsinghua University, Hsinchu 30013, Taiwan.
Optics Express (Impact Factor: 3.49). 11/2011; 19(24):24577-82. DOI: 10.1364/OE.19.024577
Source: PubMed


We report forward and backward THz-wave difference frequency generations at 197 and 469 μm from a PPLN rectangular crystal rod with an aperture of 0.5 (height in z) × 0.6 (width in y) mm(2) and a length of 25 mm in x. The crystal rod appears as a waveguide for the THz waves but as a bulk material for the optical mixing waves near 1.54 μm. We measured enhancement factors of 1.6 and 1.8 for the forward and backward THz-wave output powers, respectively, from the rectangular waveguide in comparison with those from a PPLN slab waveguide of the same length, thickness, and domain period under the same pump and signal intensity of 100 MW/cm(2).

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