A numerical simulation is performed to study the far-field diffraction properties of planar diamond waveguides. The far-field intensity distributions of a planar air waveguide and a diamond waveguide with different distances are given by numerical calculations. In the experiment, the diffraction patterns on the screen with different distances are recorded using a He-Ne laser as the light source, wherein the laser beam is coupled with and propagates in the diamond waveguide. The simulation results are found to be consistent with the experimental ones.

A photon sieve can be composed of a large number of circular pinholes. Each circular pinhole has a contribution to the focusing. For the case of point-to-point imaging, the focusing contribution of an individual circular pinhole can be analytically given. We investigate the dependence of the focusing contribution on the order m of local ring of underlying traditional Fresnel zone plate. In particular, we find that the focusing contribution is simply inversely proportional to the order m. We also present an intuitive explanation. These results are helpful for better understanding of the focusing property of photon sieves.

A reflecting ring focusing system for laser propulsion has been designed. A paraboloidal reflector of higher order is constructed to focus the laser energy on a ring which can produce a tire liked ignition region in the thruster. Considering the angle of laser incidence and reflector's coarseness, mathematic models of the focusing performance have been set up through ray tracking method. Moreover, numerical simulations of the shape, size, energy density and spatial characteristics of ignition wire are carried out in order to know the ring focusing system's superiority. The results show that the ring ignition region with a radius of 49 mm produced by a ring focusing system is about one order of magnitude larger than that produced by single point focusing system, which makes the heating of the work substance much more uniformly. Also, the ring focusing system has a better coarseness endurance.

The property of femtosecond laser pulse propagation in a metallic nano-slit lens, which is composed of nano-slits with variant widths, is investigated by using the finite-difference time-domain method. By appropriately setting the width profile of the arrayed nano-slits, we find that the femtosecond laser pulse can be focused on a nano-scale spot, while the pulse shape is well maintained beyond the spot location.