A methodology to predict shock and vibration levels that could lead to the failure of MEMS devices is reported as a function of vibration frequency and shock pulse duration. A combined experimental-analytical approach is developed, maintaining the simplicity and insightfulness of analytical methods without compromising on the accuracy characteristic of experimental methods. The minimum frequency-dependent acceleration that will lead to surfaces coming into contact, for vibration or shock inputs, is determined based on measured mode shapes, damping, resonant frequencies, and an analysis of failure modes, thus defining a safe operating region, without requiring shock or vibration testing. This critical acceleration for failure is a strong function of the drive voltage, and the safe operating region is predicted for transport (unbiased) and operation (biased condition). The model was experimentally validated for over-damped and under-damped modes of a comb-drive-driven silicon-on-insulator-based tunable grating. In-plane and out-of-plane vibration (up to 65 g) and shock (up to 6000 g) tests were performed for biased and unbiased conditions, and very good agreement was found between predicted and observed critical accelerations.

Abstract:Coupling light from an optical fibre to small optical waveguides is particularly problematic in semiconductors, since the refractive index of the silica fibre is very different from that of a semiconductor waveguide. There have been several published methods of achieving such coupling, but none are sufficiently efficient whilst being robust enough for commercial applications. In this paper experimental results of our approach called a Dual-Grating Assisted Directional Coupler, are presented. The principle of coupling by this novel method has been successfully demonstrated, and a coupling efficiency of 55% measured. O. Boyraz and B. Jalali, "Demonstration of 11dB fiber-to-fiber gain in a silicon Raman amplifier," IEICE Elect. Express 1, 429-434 (2004

Abstract-There is a trend towards miniaturization of silicon photonic circuits due to superior performance and small cost. Design rules that must be imposed on the geometry of optical waveguides to make them behave as polarization-independent and singlemode devices are well known for waveguides with relatively large cross sections and for some small cross-sectional rib waveguides with vertical sidewalls and an air top cladding. The influence of the top oxide cover on waveguide birefringence was analyzed recently, but only for relatively large cross-sectional waveguides. This paper reports simulations for both single-mode and polarization-independent behavior for small cross-sectional waveguides with variable rib width, etch depth, top oxide cover thickness, and sidewall angle. The results show that the stress-induced effects must be taken into account to satisfy both requirements. Design rules to maintain birefringence-free operation and to satisfy single-mode behavior for small rib silicon-on-insulator (SOI) waveguides are presented.

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In this paper we present our work on three silicon waveguide structures that are suitable for three different wavelength regions: near-, mid-and far-infrared. Design rules for standard rib SOI waveguides are given. Both single mode and polarisation independence in these waveguides are discussed. A hollow core waveguide suitable for gas sensing applications in the mid-infrared wavelength region is also analysed. Finally, fabrication and experimental results for free standing waveguides, which may find application in the mid and perhaps far-infrared wavelength region, are presented.

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Channel dropping waveguide filters based on single and multiple resonators in silicon-on-insulator (SOI) technology are of great interest due to their compactness and high wavelength selectivity, which is a desirable feature for photonic modulators, detectors, and other optically integrated components in telecommunication systems, in particular for wavelength division multiplexing (WDM) systems. Particular advantage of these filters is that they are capable of producing relatively large free spectral range (FSR) as well as narrow 3-dB bandwidth of the filter resonances. Herein we report experimental results and discuss the possibility of designing mono-mode and (nearly) polarization independent SOI ring and racetrack resonators with the FSR in excess of 30 nm.OCIS codes: 130.0130, 250.0250, 230.7370, 260.3060, 260.5430. doi: 10.3788/COL20090704.0291. Miniaturization of photonic devices has been significantly intensified in the last decade in an attempt to improve a footprint and performance of integrated optical components. Silicon-on-insulator (SOI) has emerged as a promising material choice for various integrated optoelectronic devices [1] . It is attractive for complex optical systems as the cost can be significantly reduced due to the compatibility with complementary metal oxide semiconductor (CMOS) technology [2] . It also has a high refractive index contrast between the core and the cladding, which is an important property for good confinement of light and efficient guiding and coupling in sub-micron waveguides. However, for those devices that are intended to be part of broadband optical networks, for example multiplexers and de-multiplexers, it is desirable to demonstrate a high selectivity and a tunable response. Thus, it is necessary to provide wavelength selective elements with the ability to filter input data streams producing a large free spectral range (FSR), a small full-width at half-maximum (FWHM), and a high quality factor (Q), and all conditions set by communication standards. Owing to the generic and adaptable operation, ring-resonator-types of filters in SOI are often considered as candidates to meet these demands.In silicon photonics, there is a particular focus on two waveguide architectures upon which the devices are typically built. Rib waveguides have proven to be particularly useful regarding polarization properties [3] . Single-mode and polarization independent (PI) resonators on rib waveguides have already been experimentally demonstrated [4] , but their FSR is usually small for applications in optical networks. On the other hand, strip waveguides, or photonic wires, allow small bend radii [5,6] , which in turn results in the improved FSR. They have to be rather small in cross-section to prevent higher-order modes (HOMs) from propagation [7] , and they exhibit polarization dependence and loss issues.In majority of applications, single-mode devices are required in order to minimize dispersion caused by multiple spatial modes which, in turn, allows for more information to be transmi...

Silicon Photonics is experiencing a dramatic increase in interest due to emerging applications areas and several high profile successes in device and technology development. Despite early work dating back to the mid 1980s, dramatic progress has been made in recent years. Whilst many approaches to research have been developed, the striking difference between the work of the early to mid 1990s, and more recent work, is that the latter has been associated with a trend to reduce the cross sectional dimensions of the waveguides that form the devices. The question arises therefore as to whether one should move to very small strip waveguides (silicon wires) of the order of 250nm in height and a few hundred nanometres in width for improved device 2 performance but with little hope of polarisation independence, or to utilise slightly larger rib waveguides that offer more opportunity to control the polarisation dependence of the devices. In this paper we discuss devices suitable for one approach or the other and present designs associated both with strip and rib waveguides. In particular, we present designs of polarisation independent ring resonators with FSRs up to 12nm, we propose modulators for bandwidths in the 10s of GHz regime, and we present grating based couplers for rib and strip waveguides, and/or for wafer scale testing, as well as a novel means of developing Bragg gratings via ion implantation.