Optical MEMS switching technology has attracted attention in managing data flow due to its compactness and
robustness. It allows hundreds of optical channels to be switched by micro-mirrors with very low power consumption.
Furthermore, the ability to switch signals independent of data rates, formats, wavelengths and protocols is advantageous
in many real world environments such as internet peering exchanges, undersea cable landing locations and data centers.
All of these applications require a highly reliable and stable switching system. Dielectric isolation has a huge impact on
major failure modes of capacitive MEMS devices such as breakdown and charging. This issue becomes more
challenging in electrostatic MEMS optical switches since they usually operate at relatively high voltages. The charges
trapped in this dielectric layer could cause interference in the electric field, resulting in erratic responses of the steering
mirrors and instability of pointing accuracy over temperature and time, which greatly degrades the system performance.
Aiming at reducing charging and preventing high voltage breakdown, a dielectric charging guard has been developed by
using an oxide "fence" with extended breakdown path length that is shielded by conductive sidewalls of the silicon
interposer. In this paper, the reliability tests as well as the performance impact to the optical switch will be presented,
including characterizations of breakdown voltage, leakage current, and charging verses temperature. The test results
demonstrate highly repeatable switching accuracy of micro-mirrors with very low drift at varied temperature. Failures
induced by fabrication will also be discussed.
growth of data and video transport networks. All-optical switching eliminates the need for optical-electrical conversion
offering the ability to switch optical signals transparently: independent of data rates, formats and wavelength. It also
provides network operators much needed automation capabilities to create, monitor and protect optical light paths. To
further accelerate the market penetration, it is necessary to identify a path to reduce the manufacturing cost significantly
as well as enhance the overall system performance, uniformity and reliability. Currently, most MEMS optical switches
are assembled through die level flip-chip bonding with either epoxies or solder bumps. This is due to the alignment
accuracy requirements of the switch assembly, defect matching of individual die, and cost of the individual components.
In this paper, a wafer level assembly approach is reported based on silicon fusion bonding which aims to reduce the
packaging time, defect count and cost through volume production. This approach is successfully demonstrated by the
integration of two 6-inch wafers: a mirror array wafer and a "snap-guard" wafer, which provides a mechanical structure
on top of the micromirror to prevent electrostatic snap-down. The direct silicon-to-silicon bond eliminates the CTEmismatch
and stress issues caused by non-silicon bonding agents. Results from a completed integrated switch assembly
will be presented, which demonstrates the reliability and uniformity of some key parameters of this MEMS optical
In this paper, a new method for interconnecting free-space
micro-optoelectromechanical system (MOEMS) devices is
developed. The heterogeneous design and assembly concept is demonstrated by a pair of V-shape actuators and related
assembly mechanism, fabricated on a silicon-on-insulator (SOI) wafer. A two-channel free-space DWDM filter has
been assembled and characterized. The results show low insertion losses. The device architecture allows hybrid optical
system integration on a single platform. The assembled optical devices can be made of different materials, on different
substrates and/or with incompatible fabrication techniques. The integration platform provides potentials for realizing a
micro optical bench with equivalent optical performance that currently require bulk optics setups.
Microassembly is an enabling technology to build 3D microsystems consisting of microparts made of different materials and processes. Multiple microparts can be connected together to construct complicated in-plane and out-of-plane microsystems by using compliant mechanical structures such as micro hinges and snap fasteners.
This paper presents design, fabrication, and assembly of an active locking mechanism that provides mechanical and electrical interconnections between mating microparts. The active locking mechanism is composed of thermally actuated Chevron beams and sockets. Assembly by means of an active locking mechanism offers more flexibility in designing microgrippers as it reduces or minimizes mating force, which is one of the main reasons causing fractures in a microgripper during microassembly operation.
Microgrippers, microparts, and active locking mechanisms were fabricated on a silicon substrate using the deep reactive ion etching (DRIE) processes with 100-um thick silicon on insulator (SOI) wafers. A precision robotic assembly platform with a dual microscope vision system was used to automate the manipulation and assembly processes of microparts. The assembly sequence includes (1) tether breaking and picking up of a micropart by using an electrothermally actuated microgripper, (2) opening of a socket area for zero-force insertion, (3) a series of translation and rotation of a mating micropart to align it onto the socket, (4) insertion of a micropart into the socket, and (5) deactivation and releasing of locking fingers. As a result, the micropart was held vertically to the substrate and locked by the compliance of Chevron beams. Microparts were successfully assembled using the active locking mechanism and the measured normal angle was 89.2°. This active locking mechanism provides mechanical and electrical interconnections, and it can potentially be used to implement a reconfigurable microrobot that requires complex assembly of multiple links and joints.
Polymers have been considered as one of the most versatile materials in making optical devices for communication and sensor applications. They provide good optical transparency to form filters, lenses and many optical components with ease of fabrication. They are scalable and compatible in dimensions with requirements in optics and can be fabricated on inorganic substrates, such as silicon and quartz. Recent polymer synthesis also made great progresses on conductive and nonlinear polymers, opening opportunities for new applications. In this paper, we discussed hybrid-material integration of polymers on silicon-based microelectromechanical system (MEMS) devices. The motivation is to combine the advantages of demonstrated silicon-based MEMS actuators and excellent optical performance of polymers. We demonstrated the idea with a polymer-based out-of-plane Fabry-Perot filter that can be self-assembled by scratch drive actuators. We utilized a fabrication foundry service, MUMPS (Multi-User MEMS Process), to demonstrate the feasibility and flexibility of integration. The polysilicon, used as the structural material for construction of 3-D framework and actuators, has high absorption in the visible and near infrared ranges. Therefore, previous efforts using a polysilicon layer as optical interfaces suffer from high losses. We applied the organic compound materials on the silicon-based framework within the optical signal propagation path to form the optical interfaces. In this paper, we have shown low losses in the optical signal processing and feasibility of building a thin-film Fabry-Perot filter. We discussed the optical filter designs, mechanical design, actuation mechanism, fabrication issues, optical measurements, and results.
Optical second-order nonlinear thin film was developed by doping dye organic molecules in a UV curing epoxy host polymer system and followed by an electric field poling step. The nonlinear optical polymeric thin film fabrication will be described. Results from a systematic evaluation of the film physical and optical properties using AFM, ellipsometer and Maker Fringe will be presented. The film absorption spectrum shows a promising advantage for frequency doubling in the blue color window. Optical nonlinear constants extraction from the Maker Fringe raw data will also be discussed.
Electro-optical channel waveguide is fabricated using an optical nonlinear polymer developed by doping dye organic molecules in a host polymer system and followed by an electric field poling step. A single-mode polymeric electrooptical channel waveguide is modeled using the <i>BeamProp</i>. Photolithography followed by wet chemical etching is used to fabricate the polymeric channel waveguide. A fabrication process is described. Results from a systematic evaluation of the film and waveguide physical and optical properties using AFM, profilometer, ellipsometer and the Maker Fringe technique is presented.
Optical communication and sensor industry face critical challenges in manufacturing for system integration. Due to the assembly complexity and integration platform variety, micro optical components require costly alignment and assembly procedures, in which many required manual efforts. Consequently, self-assembly device architectures have become a great interest and could provide major advantages over the conventional optical devices. In this paper, we discussed a self-assembly integration platform for micro optical components. To demonstrate the adaptability and flexibility of the proposed optical device architectures, we chose a commercially available MEMS fabrication foundry service - <i>MUMPs</i> (Multi-User MEMS Process). In this work, polysilicon layers of MUMPS are used as the 3-D structural material for construction of micro component framework and actuators. However, because the polysilicon has high absorption in the visible and near infrared wavelength ranges, it is not suitable for optical interaction. To demonstrate the required optical performance, hybrid integration of materials was proposed and implemented. Organic compound materials were applied on the silicon-based framework to form the required optical interfaces. Organic compounds provide good optical transparency, flexibility to form filters or lens and inexpensive manufacturing procedures. In this paper, we have demonstrated a micro optical filter integrated with self-assembly structures. We will discuss the self-assembly mechanism, optical filter designs, fabrication issues and results.