Bisheng Quan

Optimal Utilization with Fairness and Priority Considerations in Optical Networks Based on Light Trail

In this paper we consider unidirectional optical busses that originate at a convener node and end at a terminator node. Nodes can transmit only to nodes that are farther downstream, hence the convener node can not receive any bus traffic and the terminator node can not place any information on the bus. The bus supports both data traffic which is bursty as well as connections between source to destination pairs. We assume there exists a control channel outside of the bus that lets the terminator node send information to the convener node. We propose a cycle based protocol where in each cycle all nodes send their requirement to the terminator node which then sends out estimated requirements via the convener node. Then in a distributed computation individual nodes compute their utilization for that cycle based on their priority while paying attention to fair allocation for itself and other nodes. In the process a node may adjust its priority above or below the predicted value. Using simulation we evaluated of the capacity fairness and preemption fairness per node under the constraint of maximum access delay. In order to solve this problem, in this paper we consider unidirectional optical busses that originate at a convener node and end at a terminator node. Nodes can transmit only to nodes that are farther downstream, hence the convener node can not receive any bus traffic and the terminator node can not place any information on the bus. The bus supports both data traffic which is bursty as well as connections between source to destination pairs. We assume there exists a control channel outside of the bus that lets the terminator node send information to the convener node. For this type of network we propose a cycle based protocol where in each cycle all nodes send their requirement to the terminator node which then sends out estimated requirements via the convener node. Then in a distributed computation individual nodes compute their utilization for that cycle based on their priority while paying attention to fair allocation for itself and other nodes. In the process a node may adjust its priority above or below the predicted value. Using simulation we evaluated of the capacity fairness and preemption fairness per node under the constraint of maximum access delay.

Realization of ultra-broadband dispersion-flattened in dual-cladding photonic crystal fiber

We design a kind of dual-cladding photonic crystal fiber (DC-PCF), in which air holes arranged in the vicinity of the core (inner-cladding) is smaller than the other air holes (outer-cladding). By numerical simulation, the dispersion characteristic of this novel PCF is investigated. Dispersion curves will become comparatively flat while gradually reducing the air holes arranged in inner cladding under fixing the air holes of outer cladding. An ultra-flattened dispersion can be realized when the air holes size of inner-cladding dwindling down to an optimum size. As an example, the DC-PCF demonstrates an extraordinary flattened dispersion around 9.8ps/nm.km within ±0.4ps/nm/km fluctuation range in an ultra-broad wavelength range from 1.0μm to 2.0μm . Furthermore, when the air holes arranged in the second layer nearing the core is reduced slightly, the flattened dispersion curve even can parallel shift from 11.8ps/nm/km to 7.8ps/nm/km, 6.2ps/nm/km, 4.0ps/nm/km at the wavelength around 1.55μm.

The study on the compound X-ray refractive lens using LIGA technique

A theoretical method of focusing X-rays by the compound X-ray refractive lens is presented in this paper. The authors report their resent theoretical results including the material selection and structure parameters for such a device. As an example, a compound X-ray refractive lens with PMMA material is designed. The detailed fabrication process of the PMMA compound lens by LIGA technology is described. Moreover, some measured results by means of SEM are also shown. The structure height of one of the PMMA compound lens is measured to be 500μm.

The design and experiments of the super-resolving annular binary filters based on genetic algorithm

Annular binary filters that can fulfill the superresolution are designed and produced. The transverse and axial resolution gains of the filters are defined. The transverse gain is optimized by genetic algorithm to obtain the optimal structure parameters. The designed filter has a transverse gain of 1.37. The distributions of the transverse and axial intensity of the designed filters and the general circular pupil is illustrated, from which we can see that the spot size of the former is reduced by 30% and the depth of focus is increased compared with the latter. The optical system for testing the performances of the binary annular filters was build. The experimental results show the binary annular filter has fulfilled the superresolution.

The study on the epoxy resin compound x-ray refractive lens

In this paper, the authors report their resent results of the study on the epoxy resin compound X-ray refractive lens. At the first, the theoretical results of the structure parameters for such a device are given. Then, the fabrication technologies are presented. They are deep soft X-ray lithography, mold-manufacturing and molding. The material of X-ray photoresist is PMMA, the mold is made of silicone rubber, and the material of the lens is epoxy resin. Some measured results by means of optical microscope and SEM are also shown. The structure height of the epoxy resin compound lens is measured to be 500 micrometers.

A system based on non-orthogonal FDTD algorithm for analyzing photonic crystals

Photonic crystals have been widely studied in the fields of physics, material science and optical information technology. In general, the standard rectangular FDTD method is used to predict the performances of photonic crystals even if it is very time consuming and inefficient for the structures with non-orthogonal structures or inhomogeneous media. The current authors developed a software called GCFE, which is based on non-orthogonal FDTD method .The upgraded version of GCFE software can be used to calculate the photonic band structures, states density, transmission and reflection coefficients of one dimensional to three dimensional photonic crystals. It has the characteristic of efficient calculation and simple manipulation. In the present paper, the system structure of GCFE software is presented and the implementation of the algorithm module and the result display module are described in detail. Finally the band structures, transmission and reflection coefficients and photonic states density for the photonic crystal fibers with cube structures are calculated by our GCFE software and the numerical application results are also shown and discussed.

Temporal instability of phase conjugate beam in a self-pumped Ce: BaTiO 3 phase conjugator at 532 nm

Experimental results are reported on temporal instability of phase conjugate beam in a self-pumped Ce: BaTiO3 phase conjugator at 532nm. The transition from stable output to unstable one is studied for various input powers, beam diameters and incident angles. Novel results that the phase conjugate output will be unsteady when control parameter PS is within a range of 2220~3897 mW/cm2 are presented. A qualitative analysis to temporal instability that instability behaviors result from competitions among the backscattering centers is given.

Sub-picosecond chirped return-to-zero nonlinear optical pulse propagating in dense dispersion-managed fibre

By numerical simulation, we show that the fourth-order dispersion (FOD) makes sub-picosecond optical pulse broaden as second-order dispersion (SOD), makes optical pulse oscillate simultaneously as third-order dispersion (TOD). Based on above two reasons, sub-picosecond optical pulse will be widely broaden and lead to emission of continuum radiation during propagation. Here, resemble to two- and third-order dispersion compensation, fourth-order dispersion compensation is also suggested in a dispersion-managed optical fiber link, which is realized by arranging two kinds of fiber with opposite dispersion sign in each compensation cell. For sake of avoiding excessively broadening, ultra short scale dispersion compensation cell is required in ultra high speed optical communication system. In a full dispersion compensation optical fiber system which path average dispersion is zero about SOD, TOD, and FOD, even suffering from affection of high order nonlinear like self-steep effect and self-frequency shift, 200 fs gauss optical pulse can stable propagate over 1000 km with an optimal initial chirp. When space between neighboring optical pulse is only 2 picoseconds corresponding to 500 Gbit/s transmitting capacity, eye diagram is very clarity after 1000 km. The results demonstrate that ultra short scale dispersion compensation including FOD is need and effective in ultra-high speed optical communication.

The three-dimensional focusing behaviors of compound x-ray lenses

A theoretical method for evaluating the three-dimensional focusing performances of the compound x-rays lenses is presented in the present paper. The relationship between the transverse and axial focusing behaviors is considered and a simple calculation that predicts the transverse and axial focusing behaviors of the compound x-ray lenses is also presented. As an example, the three-dimensional focusing performance of a compound x-ray lens with Al material is predicted. The dependences of the three-dimensional focusing performances on the compound lenses’ structural parameters are observed for the Al compound x-ray lens. Moreover, the approximate tolerances in the setting of the receiving planes are also considered for x-rays of 4.95keV, 14.99keV and 29.78keV.