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We demonstrate unique reflective properties of light from bare and gold-coated InP nanowire (NW) photonic crystal arrays. The undoped wurtzite InP nanowire arrays are grown by selective area epitaxy and coated with a 12-nm thick Al₂O₃film to suppress atmospheric oxidation. A nominally 10-nm thick gold film is deposited around the NWs to investigate plasmonic effects. The reflectance spectra show pronounced Fabry-Perot oscillations, which are shifted for p- and s-polarized light due to a strong intrinsic birefringence in the NW arrays. Gold-coating of the NW array leads to a significant increase of the reflectance by a factor of two to three compared to the uncoated array, which is partially attributed to a plasmon resonance of the gold caps on top of the NWs and to a plasmonic antenna effect for p-polarized light. These interpretations are supported by finite-difference-time-domain simulations. Our experiments and simulations indicate that NW arrays can be used to design micrometer-sized polarizers, analyzers, and mirrors which are important optical elements in optoelectronic integrated circuits. 

Abstract This work investigates the polarization state of light diffracted from uncoated and gold‐coated InP nanowire photonic crystal arrays grown by selective area epitaxy. Experimental data and finite‐difference time‐domain simulations show that both the intensity and the ellipticity of the polarization state of the diffracted light beam can be controlled by the nanowire dimensions and gold coating, while the diffracted angle remains unchanged with respect to variations of these parameters. A nominally 10 nm‐thick gold film deposited around the nanowires enhances the diffraction intensity by plasmonic effects. These results demonstrate that the controlled conversion of incident linearly polarized light to circularly polarized or rotated linearly polarized diffracted light can find applications in photonic integrated circuits. The high sensitivity of the polarization state with respect to alterations of the nanowire dimension opens new prospects in the areas of semiconductor metrology and microchip inspection as well as for submicron particle detection.