Papers by Keyword: Waveguide

Abstract: In this work, we successfully developed a process to fabricate dual-channel polymeric waveguide filters based on an asymmetric Bragg coupler using holographic interference techniques, soft lithography, and micro molding. At the cross- and self-reflection Bragg wavelengths, the transmission dips of approximately –16.5 and –11.7dB relative to the 3dB background insertion loss and the 3dB transmission bandwidths of approximately 0.6 and 0.5nm were obtained from an ABC-based filter. The transmission spectrum overlaps when the effective index difference between two single waveguides is less than 0.0025.

Abstract: Propagation properties of TE mode for the symmetric waveguide made of left-handed material surrounded by metal substrate- and coat- layers are studied. The guidance conditions of TE mode is deduced by transmission matrix. Using graphical method, different propagation modes and corresponding transverse profiles of electric field are analyzed. It is found that the fundamental mode TE0 does not exists, such waveguide can support surface wave modes. There is a significant effect on transverse profile of order m and so on. This result will play a theoretical guidance for the research of waveguide containing left-handed materials.

Abstract: A near-field megasonic system for cleaning semiconductors was designed and fabricated. For the design of the near-field megasonic system, an impedance characteristic of a quartz megasonic waveguide with the piezoelectric actuator was analyzed using a finite element method (FEM). The analysis result showed that the anti-resonance frequency of the system was 982 kHz, which agreed well with the measured value of 988 kHz. The performance of the developed system was assessed by measuring acoustic pressures and comparing the maximim values of them with a conventional megasonic system. As a result, the maximim acoustic pressure of the developed system was decreased by 46.2% compared to the commercial system. Finally, the particle removal efficiency (PRE) test was performed and the obtained PRE was 90.8%. Theses results explain that the developed megasonic has an improved uniformity of the acoustic pressures, which can raise the energy efficiency of the system and lowering the consumption of chemical and ultra pure water (UPW).

Abstract: The band gap of 2D perfect and defect phononic crystal are calculated by using plane-wave expansion (PWE) and supercell plane wave method, which is consist of Al2O3 embedded in the epoxy resin with a square arrangement. Compared to the perfect, the gap of defect will become wider. As the size of defect length ld varied, the band structure changed. It is found that the acoustic wave only propagates along the path of defect when the propagation of acoustic wave is simulated on the 900 bending defect phononic crystals by matlab. It means that the waves are localized. So the defect mode of phononic crystal can be used as acoustic waveguide along the specific path.

Abstract: Terahertz waves can pass through silicon wafer with less loss than traditional lenses. By selecting square, circular and sectors as building blocks, a serial of equivalent lenses for terahertz wave transmission were designed in the vertical plane of the silicon wafer, including hemispherical convex, concave mirror, triangular prism and spherocylinder lenses. The lens’ 2-D design in this work is much simpler than its actual 3-D shape. Besides high transmit ability, silicon wafer also has high refractive index. When a lens is oriented horizontally, it can act as a graded-index photonic crystal waveguide, due to the existence of a band gap, especially for cylinder and prism lens.

Abstract: This paper focuses on the optical mode analysis of laser diodes to improve light emission. Under the mode analysis, we compare the optical confinement factor (OCF) percentage of the emitting light from the LDs. There are two structures which we analyze: a basic GaN waveguide structure and an InGaN waveguide structure. The second structure has additional InGaN waveguides and is analyzed under two additional design variations: the concentration of Indium and the thickness of the top waveguide layer. The results of this study indicate introducing InGaN waveguide layers correlates with lower order modes (zero and first order) and increase the OCF values. The top InGaN waveguide layer, which has a higher concentration of Indium, appears to increase the OCF. However, the increased thickness of the InGaN layer causes the lower modes’ OFC to decrease. Over all, in the best case, InGaN LD has an OCF of 1.8896%, which is about a 312% improvement compared to that of GaN LD ( OCF=0.4535%).

Abstract: An integrated TOF (Tunable Optical Filter) based on thermo-optic effect in Silicon on insulator (SOI) rib waveguide is designed and simulated. The device is comprised of two high refractivity contrast Si/Air stacks, functioning as high reflectivity of DBRs and separated by a variable refractive index Si F-P cavity. The output characteristics are calculated and simulated based on Transfer Matrix Method (TMM). Wavelength tuning is achieved through thermal modulation of refractive variation of the cavity.As the cavity Si is heated,the refractive index of the cavity increases.When the temperature of cavity Si changes within100°C，the central wavelength gets a continuous 8nm shift from 1550nm to 1558nm, which is right located in the WDM (Wavelength division multiplexing) networks operating at C-band. Moreover, by calculating, the tuning sensitivity is about 0.08nm/°C. Owing to the compact size and excellent characteristics of integration, the proposed component has a promising utilization in spectroscopy and optical communication.

Abstract: Analysis of dispersion relations for guided modes in various types of planar three-layer structures containing isotropic layers based of left-handed media (LHM) is carried out. The conditions are studied for the existence of bulk and surface TE and TM modes. The waveguide resonators with distributed feedback are proposed, implemented in a structure with LHM and amplifying guiding layer.

Abstract: In this paper, feasibility of aluminium deposition on inner wall of pipes by atomic layer deposition was studied. Firstly, by solving kinetics equation of gas adsorption on the pipe inner wall, the time for the reactant to reach saturated adsorption on the wall was calculated. Secondly, according to the aluminium crystal structure, the thickness of each deposition cycle was obtained. Finally, the minimum aluminium thickness and number of atomic layer deposition cycles that can meet electromagnetic requirement of wave guide was calculated.

Abstract: Polymer, a flexible material that can be engineered and long-term stabilized, is a promising material that is readily formed into planar waveguide structures in integrated-optical devices implemented in optical systems for (tele-)communications applications. First, the general required properties of a passive polymeric waveguide material operated at the telecommunication wavelength of 1.55 m are studied, followed by a discussion on how to engineer polymers to meet requirements of specific applications. Several engineered and tested polymers were chosen to evaluate against the ideal passive polymeric waveguide material.