Kang Xie

All-angle self-collimation in two-dimensional rhombic-lattice photonic crystals

In this work, the self-collimating phenomenon in two-dimensional rhombic-lattice photonic crystals is discussed in detail. The equi-frequency contours of a rhombic-lattice rod-type photonic crystal structure are calculated with the plane wave expansion method for different lattice angles and rod radii. A broad range of flat and open equi-frequency contours is found. A rhombic-lattice photonic crystal made of 301???21 silicon rods (n?=?3.5) in air is presented as an illustration to demonstrate the broadband all-angle self-collimation. The bandwidth for all-angle self-collimation is verified to be 17.42% of the central frequency by simulations based on the finite-difference time-domain method. The all-angle self-collimation is found to be polarization-independent and the frequency for simultaneous TM and TE all-angle self-collimation is identified and verified by finite-difference time-domain simulations.

Optimum Design for Optical Antenna of Space Laser Communication System

A new aspheric surface pre-collimation lenses system for the optical antenna of space laser communication has been optimum designed by optical design software CODE-V. Meanwhile, a Cassegrain antenna with aspheric surface has been designed. By the use of Visual C++, an optical system design software has been set up to analyze optical antenna for the space laser communication system, and some simulation results have been obtained

Design of Collimation System in Space Laser Communication

In this paper, semiconductor laser beam collimation lenses system which can be used in space laser communication has been optimum simulated and designed. Some new design methods based on the geometrical optical theory have been discussed in details, and an ideal aspheric surface design method has been given. The optical system has been further simulated by optical design software CODE-V. The collimation laser beam divergence angles have been obtained by experimental measure with laser beam analyzer. Experimental test results showed that it can be achieved a good collimation effect. This optimum design laser beam collimation system can be widely used in modern space laser communication

Self-Collimation in Square Lattice Two Dimensional Photonic Crystals with Ring-Shaped Holes

We demonstrate self-collimation phenomena based on a new type of photonic crystals made of square lattice with ring shaped holes. The plane wave expansion (PWE) method is used to get the three dimensional band diagram and equi-frequency of the second band which displays the self-collimation phenomena for the structure we proposed in this paper. The collimation angle is mainly depending on the maximum flatness half width (MFHW) of the equi-frequency. The FDTD method is employed to demonstrate the electric field amplitude distributions for the collimation phenomena. Partly, in order to achieve high efficient coupling of the input and output port, we modify both surface structures to modulate the wave-front to obtain desired effect. The parameter of the input surface is modified which will prevent the production of surface modes which takes away the EM power and enhance the transmittance. For a square lattice with the modified parameters at each side of the input surface, the surface modes are suppressed to couple with the continuum of the dielectric waveguide modes. More importantly, they might have potential application in integrated optical circuits.

Simulation design for radial Bragg fiber

By simplifying the structure of the cladding layers, an unequal-period radial Bragg fiber has been proposed. Furthermore, in this Bragg fiber, the number of cladding medium layers can be reduced. Some computer simulation results have been obtained. The simplification of the cladding layers is very useful for the fabrication of Bragg fiber.

Simulation Design for a New Non-Periodic Structure Coaxial Bragg Fiber

A new non-periodic structure of coaxial Bragg fiber has been optimum designed to improve the guided out-flux transmit characteristics. The number of cladding medium layers can be reduced by the reasonable simplify design for the non-periodic cladding structure coaxial Bragg fiber, it can achieve better field confinement than Bragg fiber in the same cladding layers structure. The structure simplification for the cladding layers is useful for the fabrication of the fiber

Optimum Structure Design for Hollow Bragg Fiber

A new unequal-period radial hollow Bragg fiber structure has been optimum designed to improve the guided flux transmit characteristics. The core of this Bragg fiber is composed of air, and the cladding is formed by a set of alternating layers of up-doped and down-doped silica. The number of the cladding medium layers can be reduced greatly, and some simulation results have been obtained. The simplification of the cladding layers is useful for the fabrication of Bragg fiber.

Simulation for integrated optical fiber head of multilayers parallel storage

Based on DWDM technology, optical fiber head can be used to realize multi-wavelengths parallel transmission. An integrated optical fiber head has been optimum designed, which can be used in the multi-layers storage system. The pick-up signal intensity distributions have been simulated for the multi-layers parallel storage system.