Hong-Guo Li

Experimental observation of classical subwavelength interference with a pseudothermal light source.

We report the experimental observation of classical subwavelength double slit interference with a pseudothermal light source. The experimental results are in good agreement with the theoretical simulation using the second order correlation function for the thermal light.

Quantum confinement effect in ZnO thin films grown by pulsed laser deposition

High quality crystalline nanostructured ZnO thin films were fabricated by pulsed laser deposition on (0001) sapphire substrates. The films were investigated by x-ray diffraction, scanning electron microscopy, and optical absorption spectroscopy. The exciton peak energy from absorption spectra was used to determine the band gap energy Eg, which was found to increase systematically with the decrease in the mean grain size and ranged from 3.388to3.647eV. This is consistent with the quantum confinement model and, up until now, not observed in a convincing manner in the ZnO thin films.

Grain size dependence of electrical and optical properties in Nb-doped anatase TiO2

Anatase thin films of pure TiO2 and 6% niobium doped TiO2 (Nb:TiO2) were fabricated on LaAlO3(100) by pulsed laser deposition. The electrical properties of Nb:TiO2 films are grain-size dependent, i.e., the larger grain size, the higher conductivity, and mobility. For all TiO2 and for Nb:TiO2 with small mean grain size (d 15 nm), particularly, a blueshift in Nb:TiO2 is governed by the Burstein–Moss effect.

Experimental observation of sub-Rayleigh quantum imaging with a two-photon entangled source

It has been theoretically predicted that N-photon quantum imaging can realize either an N-fold resolution improvement (Heisenberg-like scaling) or a N-fold resolution improvement (standard quantum limit) beyond the Rayleigh diffraction bound, over classical imaging. Here, we report the experimental study on spatial sub-Rayleigh quantum imaging using a two-photon entangled source. Two experimental schemes are proposed and performed. In a Fraunhofer diffraction scheme with a lens, two-photon Airy disk pattern is observed with subwavelength diffraction property. In a lens imaging apparatus, however, two-photon sub-Rayleigh imaging for an object is realized with super-resolution property. The experimental results agree with the theoretical prediction in the two-photon quantum imaging regime.

Lensless ghost imaging of a phase object with pseudo-thermal light

We report an experimental realization of lensless ghost imaging for a phase-only object with pseudo-thermal light, which was proposed by W. Gong and S. Han [Phys. Rev. A 82, 023828 (2010)]. In contrast with conventional ghost imaging, the scheme involves the interference of two correlated fields and the phase information of the object can be retrieved. This imaging technique completes the nonlocally lensless spatial reconstruction of both amplitude and phase distributions in ghost imaging with thermal light.