High-efficiency broadband polarization-independent binary fused silica gratings for large astronomical telescopes.

The binary fused silica gratings (BFSGs) with high diffraction efficiency are presented for large astronomical ground-based telescopes. Calculations demonstrate that the BFSGs could obtain high diffraction efficiency in a wider wavelength range and angle of incident (AOI) range compared with volume phase holographic gratings. Several gratings with a size of 60×60 have been fabricated by holographic lithography and reactive ion-beam etching technology.

Optical anisotropy of self-organized gold quasi-blazed nanostructures based on a broad ion beam.

To circumvent elaborate conventional lithographic methods for realizing metallic nanostructures, it is necessary to develop self-organized nanofabrication methods for suitable template structures and their optical characterization. We demonstrate the potential of ion bombardment with impurity co-deposition to fabricate terraced or quasi-blazed nanostructure templates. Self-organized terraced nanostructures on fused silica were fabricated using ion bombardment with iron impurity co-deposition and subsequent Au shadow deposition.

Experimental investigation of quantum key distribution over a water channel.

Quantum key distribution (QKD) has undergone significant development in recent decades, particularly with respect to free-space (air) and optical fiber channels. Here, we report a proof-of-principle experiment for the BB84 protocol QKD over a water channel. First, we demonstrate again the polarization preservation properties of the water channel in optical transmission according to the measured Mueller matrix, which is close to the unit matrix.