Research on improved methods of reduction of bend loss of silicon-on-insulator waveguides

Improved methods of reduction of bend loss of silicon-on-insulator waveguides were simulated and analyzed by means of effective index method (EIM) and two dimensional beam propagation method (2D-BPM). The simulation results indicate that two different methods, one of which are introducing an offset at the junction of two waveguides and the other is etching groove at the outside of bend waveguide, can decrease bend loss. And the later one is more effective. Meanwhile, experiments validate them. By etching groove, the insertion loss of bend waveguide of R = 16mm, transverse displacement 70mum was decreased 5dB. And its bend loss was almost eliminated.

Structural optimizations of SOI-based single-mode rib waveguide bends

Effects of structure parameters on bend loss of rib silicon-on-insulator (Sol) bend waveguides have been analyzed by means of effective index method (EIM) and 2D bend loss formula. The simulation results indicate that the bend loss decreases with the increase of bend radius and waveguide width, as well as with the decrease of the step factor of the rib waveguide. Moreover, the optional structure parameters have been found when bend waveguides are single-mode.

Mode Analysis and Design of a Low-Loss Photonic Crystal 60 degrees Waveguide Bend

The guided modes of a two-dimensional photonic crystal straight waveguide and a waveguide bend are studied in order to find the high transmission mechanism for the waveguide bend. We find that high transmission occurs when the mode patterns and wave numbers match, while the single-mode condition in the waveguide bend is not necessarily required. According to the mechanism, a simply modified bend structure with broad high transmission band is proposed. The bandwidth is significantly increased from 19 to 116 nm with transmission above 90%, and covers the entire C band of optical communication.

Integration of a photonic crystal polarization beam splitter and waveguide bend

In this work, we present the design of an integrated photonic-crystal polarization beam splitter (PC-PBS) and a low-loss photonic-crystal 60 waveguide bend. Firstly, the modal properties of the PC-PBS and the mechanism of the low-loss waveguide bend are investigated by the two-dimensional finite-difference time-domain (FDTD) method, and then the integration of the two devices is studied. It shows that, although the individual devices perform well separately, the performance of the integrated circuit is poor due to the multi-mode property of the PC-PBS. By introducing deformed airhole structures, a single-mode PC-PBS is proposed, which significantly enhance the performance of the circuit with the extinction ratios remaining above 20dB for both transverse-electric (TE) and transverse-magnetic (TM) polarizations. Both the specific result and the general idea of integration design are promising in the photonic crystal integrated circuits in the future. (C) 2009 Optical Society of America

Stepped-bend Substrate Integrated Waveguide to Rectangular Waveguide Transition

A new wideband transition between substrate integrated waveguide (SIW) and rectangular waveguide (RWG) that resembles a right angle waveguide E-bend at Ku/K band is presented. The transition has removable but stable mounting, requires only PCB fabrication and has adaptable quality and bandwidth characteristics depending on the number of substrate layers used.

Analysis of non-uniform waveguide in MZI and optimization of the power confinement in the waveguide

The technological world has attained a new dimension with the advent of miniaturization and a major breakthrough has evolved in the form of moems, technically more advanced than mems. This breakthrough has paved way for the scientists to research and conceive their innovation. This paper presents a mathematical analysis of the wave propagation along the non-uniform waveguide with refractive index varying along the z axis implemented on the cantilever beam of MZI based moem accelerometer. Secondly the studies on the wave bends with minimum power loss focusing on two main aspects of bend angle and curvature angle is also presented.

Design of S bend waveguides for delay line applications in integrated optics

A novel scheme for generation of phase using optical delay lines is proposed. The design of the optical components in the circuit which includes the S bend waveguides and straight waveguide couplers are very important for integrated optics. Beam propagation Method and MatLab is employed for the design.

Compact multimode polymer waveguide bends for board-level optical interconnects

Multimode polymer waveguides are promising for use in board-level optical interconnects. In recent years, various on-board optical interconnection architectures have been demonstrated making use of passive routing waveguide components. In particular, 90° bends have played important roles in complex waveguide layouts enabling interconnection between non co-linear points on a board. Due to the dimensions and index step of the waveguides typically used in on-board optical interconnects, low-loss bends are typically limited to a radius of ∼ 10 mm. This paper therefore presents the design and fabrication of compact low-loss waveguide bends with reduced radii of curvature, offering significant reductions in the required areas for on-board optical circuits. The proposed design relies on the exposure of the bend section to the air, achieving tighter light confinement along the bend and reduced bending losses. Simulation studies carried out with ray tracing tools and experimental results from polymer samples fabricated on FR4 are presented. Low bending losses are achieved from the air-exposed bends up to 4 mm of radius of curvature, while an improvement of 14 μm in the 1 dB alignment tolerances at the input of these devices (fibre to waveguide coupling) is also obtained. Finally, the air-exposed bends are employed in an optical bus structure, offering reductions in insertion loss of up to 3.8 dB. © 2013 IEEE.

High transmission of slow light in the photonic crystal waveguide bends

We present the research on the transmission characteristic of slow-light-mode in the photonic crystal line-defect waveguide bends on SOL After optimizing the structure parameters in the vicinity of the bends, the normalized transmission efficiency of slow-light-mode through the photonic crystal 60 degree and 120 degree waveguide bends are as high as 80% and 60% respectively, which are 10 times higher than that in the undeformed case. To slow down light further, we design novel coupled cavity waveguide bend structures with high quality-factor. High normalized transmission efficiency of 75% and low group velocity of c/170 ( c is the light velocity in vacuum) are realized. These results are beneficial to enhance the slow light effect of photonic crystal structures and improve the miniaturization and integration of photonic crystal slow light devices.

Simple method for estimating minimum bend radii of SOI single mode curved rib waveguides

A simple method based on the effective index method was used to estimate the minimum bend radii of curved SOI waveguides. An analytical formula was obtained to estimate the minimum radius of curvature at which the mode becomes cut off due to the side radiative loss.

Compact polarization-insensitive arrayed waveguide grating based on SOI material

A compact polarization-insensitive 8x8 arrayed waveguide grating with 100GHz channel spacing at 1.55 mu m is presented on the material of silicon on insulator (SOI). Increasing the epitaxial layer thickness can reduce the birefringence of the waveguide, but the wvaeguide's bend radius also increases at the same time. We choose the SOI wafer with 3.0 mu m epitaxial layer to reduce the device's size and designed the appropriate structure of rib wave-guides to eliminate the polarization dependant wavelength shift. Compared to the other methods of eliminating the polarization dependant wavelength shift, the method is convenient and easy to control the polarization without additional etching process. The index differences between TE0 and TM0 of straight and bend waveguides are 1.4x10(-5) and 3.9x10(-5), respectively. The results showed that the polarization dependant wavelength shift is 0.1nm, and the device size is 1.5x1.0 cm(2).

Comparison of Loss and Crosstalk Characteristics of SOI Based Intersecting Waveguides with Different Bend Structures

By means of two dimension beam propagation method (2D-BPM) with high order Pade approximation, behaviors of SOI waveguide based bend intersections with variant bending radius are simulated and analized. The result shows that crosstalk of intersections decreases with the increase of bending radius and intersecting angle. Furthermore, loss and crosstalk characteristics of bend intersections formed by sine bend, cosine bend and arc bend are compared. Sine bend based structures are proved that it can present lowest loss and smallest crosstalk properties among the three and may find their wide application in the design of bend intersections and other more complicated photonic devices and circuits.

Analysis and Simulation of S-shaped Waveguide in Silicon-on-insulator

The simulation and analysis of S-shaped waveguide bend are presented.Bend radius larger than 30 mm assures less than 0.5 dB radiation loss for a 4-μm-wide silicon-on-insulator waveguide bend with 2-μm etch depth.Intersection angle greater than 20° provides negligible crosstalk (＜-30 dB) and very low insertion loss.Any reduction in bend radius and intersection angle is at the cost of the degradation of characteristics of bent waveguide and intersecting waveguide, respectively.

Bend and stretch : pedagogical callisthenics in creative practice honours

The supervision of research higher degree (RHD) candidates in creative practice-led programs poses challenges for both candidates and supervisors. Changes in international postgraduate training agendas have complicated this ever-shifting terrain. This paper investigates the honours research training year. This fourth year is made up of a project and coursework and is a traditional entry point for doctoral study. At Creative Industries, honours acts as a precursor and model for supervisory practice in postgraduate creative arts in an interdisciplinary faculty. The findings indicate that best practice may involve ‘bending and stretching’ existing pedagogical approaches for an increasingly interdisciplinary and mobile research environment. This discussion considers the supervision of candidates enrolled in Queensland University of Technology Faculty of Creative Industries honours courses that encompass a range of disciplines including creative writing, fashion, animation and performance studies. We present results of an analysis of the work of honours students who are creative practitioners (many of whom will, or have, moved into the RHD environment). This examination was undertaken in order to develop an understanding of the dynamics of creative practice at this level, particularly in light of the growing emphasis on early research training in Australian universities. Specific pedagogical strategies mooted include establishing a common research vocabulary, an increasing focus on research design, and a linking of theory and practice.