Fabrication and Characterization of GaP Photonic Crystals for Terahertz Wave Application

We have fabricated GaP two-dimensional photonic crystals (PCs) for terahertz (THz) wave generation by a reactive ion etching in Ar/Cl2 gas chemistries. We performed 75-mm-deep etching of GaP, in which Al2O3 layer is applied as a hard mask with its selectivity as high as 125. We demonstrated the THz-wave generation from the fabricated GaP slab waveguide with the PC structure as a cladding layer under a collinear phase-matched difference frequency generation. In the frequency dependence of THz output power for the PC slab waveguide is seen at around 1.1 THz. From the in-plane transmission spectrum of THz-wave, we confirmed that the THz output characteristics had relation with the photonic structure for THz wave. [doi:10.2320/matertrans.MAW200728]