Long-range elastic guidance mechanisms for electrostatic comb-drive actuators

The range of motion and output force of the often used electrostatic comb-drive with folded flexure straight guidance, as shown in Figure 1, is limited by sideways instability due to poor sideways stiffness of the folded flexure at relatively large deflections [1]

Low-cost multimode waveguide couplers for multimode fiber-based local area networks

Novel, ultra-compact multimode fiber-matched integrated optical 1×2, 1×3 and 2×2 couplers with low excess losses and large tolerances have been designed and simulated using a fully three-dimensional beam propagation metho

Design and fabrication of 1xN and NxN planar waveguide couplers for multimode fiber-based local area networks.

We report on the design and fabrication of compact and potentially low-cost multimode fiber matched 1 x N and N x N couplers for LAN’s. The design utilizes the self-imaging effect and tapering of the Multi-Mode Interference (MMI) section. An extended mode propagation analysis and 3-D beam propagation method (BPM) were used to analyze and design these structures. The simulations show that the couplers exhibit low excess losses, low power imbalance, and relaxed fabrication tolerances at very short device length. The devices were fabricated in polymer waveguide technology using spin coating, photolithography, and reactive ion etching. Preliminary experimental results show promising characteristics

High effiency small-size planar hyperbolical lenses

Planar hyperbolical lenses with an average efficiency of 85% for coupling a 40 μm wide beam into a 4 μm wide waveguide are realised. The total length required for the beam compression is 600 μm, with a lateral index contrast of 0.01. Good agreement is found between the BPM predicted and the measured lens efficiencies

High effiency small-size planar hyperbolical lenses

Planar hyperbolical lenses with an average efficiency of 85% for coupling a 40 μm wide beam into a 4 μm wide waveguide are realised. The total length required for the beam compression is 600 μm, with a lateral index contrast of 0.01. Good agreement is found between the BPM predicted and the measured lens efficiencies

High efficiency small-size planar hyperbolical lenses

Planar hyperbolical lenses with an average efficiency of 85% for coupling a 40 mu m wide beam into a 4 mu m wide waveguide are realised. The total length required for the beam compression is 600 mu m, with a lateral index contrast of 0.01. Good agreement is found between the BPM predicted and the measured lens efficiencie

Evaluation of polymer based third order nonlinear integrated optics devices

Nonlinear polymers are promising materials for high speed active integrated optics devices. In this paper we evaluate the perspectives polymer based nonlinear optical devices can offer. Special attention is directed to the materials aspects. In our experimental work we applied mainly Akzo Nobel DANS side-chain polymer that exhibits large second and third order coefficients. This material has been characterized by third harmonic generation, z-scan and pump-probe measurements. In addition, various waveguiding structures have been used to measure the nonlinear absorption (two photon absorption) on a ps time-scale. Finally an integrated optics Mach-Zehnder interferometer has been realized and evaluated. It is shown that the DANS side-chain polymer has many of the desired properties: the material is easily processable in high-quality optical waveguiding structures, has low linear absorption and its nonlinearity has a pure electronic origin. More materials research has to be done to arrive at materials with higher nonlinear coefficients to allow switching at moderate light intensity (< 1 W peak power) and also with lower nonlinear absorption coefficients

Compact polymer components for an integrated add-drop multiplexer

A phasar and a digital thermo optic switch have been designed and processed in a high index contrast polymer technology. Both devices are small enough to fabricate two integrated add-drop multiplexers on one 4 inch wafe

On the sound absorption coefficient of porous asphalt pavements for oblique incident sound waves

A rolling tyre will radiate noise in all directions. However, conventional measurement techniques for the sound absorption of surfaces only give the absorption coefficient for normal incidence. In this paper, a measurement technique is described with which it is possible to perform in situ sound absorption measurements for oblique incidence. The measurements are performed with a small microphone array, the 8p-probe, and the theory is based on the local plane wave assumption.\ud In this paper, an approach is proposed to determine whether a surface behaves as a locally reacting surface or a nonlocally reacting surface, which is an important characteristic for optimising asphalt pavements for noise reduction and for modelling techniques.\ud Measurements at various angles of incidence are performed to demonstrate this approach as well as measurements of the absorption coefficient at normal incidence to validate the 8p-probe with impedance tube measurements