Optical MEMS Switches: Theory, Design, and Fabrication of a New Architecture

The scalability and cost of microelectromechanical systems (MEMS) optical switches are now the important factors driving the development of MEMS optical switches technology. The employment of MEMS in the design and fabrication of optical switches through the use of micromachining fabricated micromirrors expands the capability and integrity of optical backbone networks. The focus of this dissertation is on the design, fabrication, and implementation of a new type of MEMS optical switch that combines the advantages of both 2-D and 3-D MEMS switch architectures. This research presents a new digital MEMS switch architecture for 1×N and N×N optical switches. The architecture is based on a new microassembled smart 3-D rotating inclined micromirror (3DRIM). The 3DRIM is the key device in the new switch architectures. The 3DRIM was constructed through a microassembly process using a passive microgripper, key, and inter-lock (PMKIL) assembly system. An electrostatic micromotor was chosen as the actuator for the 3DRIM since it offers continuous rotation as well as small, precise step motions with excellent repeatability that can achieve repeatable alignment with minimum optical insertion loss between the input and output ports of the switch. In the first 3DRIM prototype, a 200×280 microns micromirror was assembled on the top of the electrostatic micromotor and was supported through two vertical support posts. The assembly technique was then modified so that the second prototype can support micromirrors with dimensions up to 400×400 microns. Both prototypes of the 3DRIM are rigid and stable during operation. Also, rotor pole shaping (RPS) design technique was introduced to optimally reshape the physical dimensions of the rotor pole in order to maximize the generated motive torque of the micromotor and minimize the required driving voltage signal. The targeted performance of the 3DRIM was achieved after several PolyMUMPs fabrication runs. The new switch architecture is neither 2-D nor 3-D. Since it is composed of two layers, it can be considered 2.5-D. The new switch overcomes many of the limitations of current traditional 2-D MEMS switches, such as limited scalability and large variations in the insertion loss across output ports. The 1×N MEMS switch fabric has the advantage of being digitally operated. It uses only one 3DRIM to switch the light signal from the input port to any output port. The symmetry employed in the switch design gives it the ability to incorporate a large number of output ports with uniform insertion losses over all output channels, which is not possible with any available 2-D or 3-D MEMS switch architectures. The second switch that employs the 3DRIM is an N×N optical cross-connect (OXC) switch. The design of an N×N OXC uses only 2N of the 3DRIM, which is significantly smaller than the N×N switching micromirrors used in 2-D MEMS architecture. The new N×N architecture is useful for a medium-sized OXC and is simpler than 3-D architecture. A natural extension of the 3DRIM will be to extend its application into more complex optical signal processing, i.e., wavelength-selective switch. A grating structures have been selected to explore the selectivity of the switch. For this reason, we proposed that the surface of the micromirror being replaced by a suitable gratings instead of the flat reflective surface. Thus, this research has developed a rigorous formulation of the electromagnetic scattered near-field from a general-shaped finite gratings in a perfect conducting plane. The formulation utilizes a Fourier-transform representation of the scattered field for the rapid convergence in the upper half-space and the staircase approximation to represent the field in the general-shaped groove. This method provides a solution for the scattered near-field from the groove and hence is considered an essential design tool for near-field manipulation in optical devices. Furthermore, it is applicable for multiple grooves with different profiles and different spacings. Each groove can be filled with an arbitrary material and can take any cross-sectional profile, yet the solution is rigorous because of the rigorous formulations of the fields in the upper-half space and the groove reigns. The efficient formulation of the coefficient matrix results in a banded-matrix form for an efficient and time-saving solution

Integrated silicon photonic packaging

Silicon photonics has garnered plenty of interests from both the academia and industry due to its high-speed transmission potential as well as sensing capability to complement silicon electronics. This has led to significant growth on the former, valuing at US$626.8M in 2017 and is expected to grow 3-fold to US$ 1,988.2M by 2023, based on data from MarketsandMarkets™. Silicon photonics’ huge potential has led to worldwide attention on fundamental research, photonic circuit designs and device fabrication technologies. However, as with silicon electronics in its early years, the silicon photonics industry today is extremely fragmented with various chip designs and layouts. Most silicon photonic devices fabricated are not able to reach the hand of consumers, due to a lack of information related to packaging design rules, components and processes. The importance of packaging technologies, which play a crucial role in turning photonic circuits and devices into the final product that end users can used in their daily lives, has been overlooked and understudied. This thesis aims to – 1. fill the missing gap by adapting existing electronics packaging techniques, 2. assess its scalability, 3. assess supply chain integration and finally 4. develop unique packaging approaches specifically for silicon photonics. The first section focused on high density packaging components and processes using University of California, Berkeley’s state-of-the-art silicon photonic MEMS optical switches as test devices. Three test vehicles were developed using (1) via-less ceramic and (2) spring-contacted electrical interposers for 2D integration and (3) through-glass-via electrical interposers for 2.5D heterogeneous integration. A high density (1) lidless fibre array and (2) a 2D optical interposer, which allows pitch-reduction of optical waveguides were also developed in this thesis. Together, these components demonstrated the world’s first silicon 2 photonic MEMS optical switch package and subsequently the highest density silicon photonic packaging components with 512 electrical I/Os and 272 optical I/Os. The second section then moved away from active optical coupling that was used in the former, investigating instead passive optical packaging concepts for the future. Two approaches were investigated - (1) grating-to-grating and (2) evanescent couplings. The former allows the development of pluggable packages, separating fibre coupling away from the device while the latter allows simultaneous optical and electrical packaging on a glass wafer in a single process. Lastly, the knowhow and concepts developed in this thesis were compiled into packaging design rules and subsequently introduced into H2020-MORPHIC, PIXAPP packaging training courses (as a trainer) and other packaging projects within the group

Moems 2 x 2 switch fabrics for all optical networking applications

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Qualification of Metallized Optical Fiber Connections for Chip-Level MEMS Packaging

A MEMS-based Safety and Arming (S&A) device is being developed for the next generation of Navy torpedoes. The MEMS-based S&A consists of a high aspect ratio MEMS chip fabricated by deep reactive ion etching (DRIE) of silicon on insulator substrates (SOI). The micro-machined structures, which include environmental sensors, actuators, and optical components, are susceptible to stiction related failures. A robust package is essential to transform the fragile MEMS S&A device into a rugged package capable of reliably functioning throughout the military stockpile to target sequence. To adequately protect the MEMS device from deleterious effects of the external environment, the package must be housed in a hermetic, organic-free package. This dissertation presents the design of, analyzes, and qualifies a die-level fluxless packaging concept. The die-level package consists of a metallized seal ring patterned around the perimeter of the chip, including the fiber groove, sidewalls, and base. The fiber grooves provide a fiber optic interconnect between the microstructure area and the macro-environment. A cap chip, with a matching seal ring, completes the clamshell package. Solder is deposited onto the seal ring and in the grooves at the wafer-level on the device and cap chips. A fluxless, and hence organic-free, soldering process joins and seals the fiber-chip assembly on the chip-level. The conditions that govern fluxless soldering are addressed and tailored for success in the developed design. Surface energy models are used to understand the fluxless soldering conditions and to study the geometric stability of fluid solder joints at the fiber to chip interface. Several techniques for fabrication of the chips and assembly of the packages are investigated. The effects of leak rate of the package seal on the internal package environment are discussed in detail to establish an acceptable leak rate of small volume MEMS packages. The calculations are then furthered to determine the acceptable leak path dimensions to ensure moisture does reach unacceptable levels during the package life. The presented work represents the first reported organic-free (fluxless) die-level package seal with optical fibers that cross the seal boundary

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Design and Development of an Optical Chip Interferometer For High Precision On-Line Surface Measurement

Advances in manufacturing and with the demand of achieving faster throughput at a lower cost in any industrial setting have put forward the need for embedded metrology. Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the workpiece. Providing closer integration of metrology upon the manufacturing platform will improve material processing and reliability of manufacture for high added value products in ultra-high-precision engineering. Currently, almost all available metrology instrumentation is either too bulky, slow, destructive in terms of damaging the surfaces with a contacting stylus or is carried out off-line. One technology that holds promise for improving the current state-of-the-art in the online measurement of surfaces is hybrid photonic integration. This technique provides for the integration of individual optoelectronic components onto silicon daughter boards which are then incorporated on a silica motherboard containing waveguides to produce a complete photonic circuit. This thesis presents first of its kind a novel chip interferometer sensor based on hybrid integration technology for online surface and dimensional metrology applications. The complete metrology sensor system is structured into two parts; hybrid photonic chip and optical probe. The hybrid photonic chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. Optical probe is a separate entity attached to the integrated optic module which serves as optical stylus for surface scanning in two measurement modes a) A single-point for measuring distance and thus form/surface topography through movement of the device or workpiece, b) Profiling (lateral scanning where assessment of 2D surface parameters may be determined in a single shot. Wavelength scanning and phase shifting inteferometry implemented for the retrival of phase information eventually providing the surface height measurement. The signal analysis methodology for the two measurement modes is described as well as a theoretical and experimental appraisal of the metrology capabilities in terms of range and resolution. The incremetal development of various hybrid photonic modules such as wavelength encoder unit, signal detection unit etc. of the chip interferometer are presented. Initial measurement results from various componets of metrology sensor and the surface measurement results in two measurement modes validate the applicability of the described sensor system as a potential metrology tool for online surface measurement applications

NASA Tech Briefs, January 2007

Topics covered include: Flexible Skins Containing Integrated Sensors and Circuitry; Artificial Hair Cells for Sensing Flows; Video Guidance Sensor and Time-of-Flight Rangefinder; Optical Beam-Shear Sensors; Multiple-Agent Air/Ground Autonomous Exploration Systems; A 640 512-Pixel Portable Long-Wavelength Infrared Camera; An Array of Optical Receivers for Deep-Space Communications; Microstrip Antenna Arrays on Multilayer LCP Substrates; Applications for Subvocal Speech; Multiloop Rapid-Rise/Rapid Fall High-Voltage Power Supply; The PICWidget; Fusing Symbolic and Numerical Diagnostic Computations; Probabilistic Reasoning for Robustness in Automated Planning; Short-Term Forecasting of Radiation Belt and Ring Current; JMS Proxy and C/C++ Client SDK; XML Flight/Ground Data Dictionary Management; Cross-Compiler for Modeling Space-Flight Systems; Composite Elastic Skins for Shape-Changing Structures; Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells; Aligning Optical Fibers by Means of Actuated MEMS Wedges; Manufacturing Large Membrane Mirrors at Low Cost; Double-Vacuum-Bag Process for Making Resin- Matrix Composites; Surface Bacterial-Spore Assay Using Tb3+/DPA Luminescence; Simplified Microarray Technique for Identifying mRNA in Rare Samples; High-Resolution, Wide-Field-of-View Scanning Telescope; Multispectral Imager With Improved Filter Wheel and Optics; Integral Radiator and Storage Tank; Compensation for Phase Anisotropy of a Metal Reflector; Optical Characterization of Molecular Contaminant Films; Integrated Hardware and Software for No-Loss Computing; Decision-Tree Formulation With Order-1 Lateral Execution; GIS Methodology for Planning Planetary-Rover Operations; Optimal Calibration of the Spitzer Space Telescope; Automated Detection of Events of Scientific Interest; Representation-Independent Iteration of Sparse Data Arrays; Mission Operations of the Mars Exploration Rovers; and More About Software for No-Loss Computing