Kevin Le

Electrooptically tunable folded arrayed waveguide grating multiplexer

Channel tunability of 10 GHz has been demonstrated in a 40-channel 50-GHz-spaced folded silica-on-silicon arrayed waveguide grating (AWG) multiplexer using quadratic nonlinearity in phosphorous-doped glass and a specially shaped electrode. Such AWG can be stabilized and tuned around ITU grid without power-consuming thermoelectric coolers.

An optical scanner based on electromagnetically actuated optical fiber

To meet the performance requirements for some applications, including small sizes, precise optics, low power consumption and non-electrical control in the devices, an optical fiber scanner using electromagnetic actuation has been developed. This paper acquaints a compact external magnetic field actuated fiber optic scanner, in which the main structure is an optical fiber coated with nickel magnetic gel. The advantages of device architecture are: (1) the scanner dimensions are in the same scales of an optical fiber diameter, (2) optical properties and information are well preserved in the fiber, and (3) the actuation control is external and requires no electrical wiring in scanner design and zero power consumption. In this work, magnetic properties of the nickel based ferromagnetic gel were measured in order to carry out the theoretical calculations of static response and resonant frequencies. With the dynamic waveforms of input and output signals from the position sensing device at both modes of resonant frequencies, we conclude that it is significant to operate at the resonant frequencies so that the scanner requires less power to reach large displacement and the oscillating motion of the scanner is purely sinusoidal. A simple and versatile rotary gel coating technique, static and dynamic performance characterization and potential applications of the fiber scanner will be discussed. Moreover, we will also discuss the practical issues in operation and possible waveform distortion that affects imaging and display quality.

A polymer-based Fabry-Perot filter integrated with 3-D MEMS structures

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 Micro-Assembly with Automatic Alignment Using MEMS Active Interconnects

In this article, a novel method for interconnecting micro-optoelectromechanical system (MOEMS) is presented. The design concept is proven by a pair of V-shape voltage controlled actuators that are fabricated on single silicon-on-insulator (SOI) wafer. When a DC voltage is applied to the actuators, the deformation of the actuators enables the sockets to open larger than the dimension of the optical filter block. Then, the filter block is inserted into the socket by a robotic assembly system. After releasing the applied voltage, the filter block is held by a static force that is generated from the deformation of the bent beams. A two-channel DWDM micro-system is assembled and demonstrated using this method.

An Active Interconnecting Mechanism for Free-Space Optic Applications

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.

Characterization of nonlinear optical polymers fabricated from dye doped UV curing epoxy

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.

Self-assembly micro optical filter

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 - MUMPs (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.

A Compact Fiber Optic Scanner Using Electromagnetic Actuation

Electromagnetic actuation shows promising suitability for constructing actuators and sensors with an optical fiber in terms of speeds, device dimensions, and power consumption. In this work we invented a fiber scanner which is composed of an optical fiber coated with nickel powder based ferromagnetic gel. The optical scanner, in which the optical fiber is mechanically steered with external electromagnetic fields, satisfies the applications that require small sizes, precise optics, low power consumption and prefers non-electrical control in the device. The device architecture makes the scanner dimensions in the same scales of an optical fiber diameter and the optics is well preserved in the fiber. In addition, the external actuation eliminates the needs of voltage or current in the scanner. Magnetization hysteresis curve of the nickel based ferromagnetic gel, which gives relevant magnetic material properties, is characterized in order to carry out the calculation of static and dynamic responses. A rotary gel coating technique is used to construct fiber optical scanners. The material preparation and fabrication method is described in this paper. We characterized the scanner in two modes. The static scanning results showed a 0.5 mm displacement under the influence of static magnetic field of 14.5 KA/m. At the first peak of resonant frequency in dynamic scanning, a linear displacement of 0.75 mm with a magnetic field amplitude of 6.69 KA/m was demonstrated. In this paper, we discussed the fabrication procedures and performance characterization of the fiber scanner as well as some of the potential applications.

Polymeric Electro-Optical Channel Waveguide Fabricated by Lithography and Wet Chemical Etching

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 BeamProp. 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.

Fabrication and characterization of poled Pyrylium doped nonlinear organic thin film

Organic thin film doped with Pyrylium was fabricated and characterized. Optical second-order nonlinearity was obtained after poling with electric field. Maker Fringe measurements and analysis were performed to evaluate the nonlinear coefficients. The film demonstrates negligible absorption in blue wavelengths window.