A.T.T.D. Tran

Surface micromachined Fabry-Perot tunable filter

We report the fabrication of a wavelength tunable optical filter using surface micromachining technology. The center wavelength is 1.517 /spl mu/m and the transmission bandwidth is 5 nm. The device with a 50-/spl mu/m diameter aperture has an optical loss of about 5 dB. A continuous wavelength tuning of 60 nm has been demonstrated. This device may find applications in optical sensing and wavelength division multiplexing systems, and can be readily integrated with surface emitting lasers, modulators, and detectors.

Long-wavelength resonant vertical-cavity LED/photodetector with a 75-nm tuning range

A design for a highly tunable long-wavelength LED/photodetector has been investigated. The device consists of a GaAs-based distributed Bragg reflector (DBR) that is wafer-bonded to InP-based active layers, with a surface-micromachined tunable top DBR mirror to produce the wavelength shift. A 1.5-/spl mu/m device has been fabricated with a continuous tuning range of 75 nm. An extinction ratio of greater than 20 dB existed across the entire tuning range.

Ultrafine motion detection of micromechanical structures using optical moire patterns

The use of optical moire patterns for motion and microtribology detection of micromechanical devices has been proposed and demonstrated. Using a very simple image processing technique, 50-nm in-plane motion of a micromechanical sensor has been detected. With an improved device design, the spatial resolution for in-plane motion detection will be able to reach 10 nm, meeting the most stringent requirement for any known applications for microelectromechanical systems (MEMS).

Integrated micro-optical interferometer arrays

Surface micromachining is an emerging technology that has rapidly found its applications in optoelectronics and micro-optics. Micromachining technology will become even more attractive to optical applications if micromechanical devices can be treated as readily available add-on structures to photonic devices such as lasers, detectors, and modulators for new functionalities. Recently, we have developed a low temperature, low stress surface micromachining process that has such features. Using this technology, we fabricated micromachined Fabry-Perot tunable filters and integrated them with various optical devices operating at 1.3/1.55 micron wavelength regimes.

Surface micromachined interferometer‐based optical reading technique

A surface micromachined suspended interferometer and an atomic force microscope (AFM) are incorporated into a novel optical reading technique. The AFM tip mechanically deflects the suspended membrane as it scans past a data bit on the membrane surface. The data are read by monitoring the changing interference pattern generated in the optical aperture of the interferometer. When operated in parallel, there exists the potential for high speed, high density data reading.

Electro-mechanically tunable micro Fabry-Perot filter array

We report a novel electro-mechanical tunable micro Fabry-Perot Filter (FPF) for applications in flat panel colour displays, sensors (acceleration, pressure etc.) and communications. The micro FPF is fabricated on both silicon and glass substrates. The device offers many advantages over existing surface micromachined optical technologies. The fabrication process is simple, monolithic, and does not require any high temperature step. The present device can be used in many different applications. For instance, it can be used as a colour display device by using collimated white light and appropriate mirror separation. This device requires neither as sophisticated optics nor as intense signal processing as the Digital Mirror Device (DMD).

Micromachined Micro-Optic and Optoelectronic Devices

Rencent progress on micromachined micro-optic and optoelectronic devices is discussed. We describe a low temperature (240°C) surface micromachining process that can be used to fabricate a variety of micro-optic components on micromachined membranes integrated with microactuators. The devices discussed in this paper include Fabry-Perot tunable filters with a 341 nm tuning range, wavelength tunable transmitters at 1.55 micron wavelength, high-sensitivity integrated sensors using optical Moire patterns, and movable microlenses. Such devices represent a new class of micro-optic circuits that will find important applications in many areas including optical communication and sensing.

Optical memory using an atomic force microscope and a surface micromachined interferometer

Summary form only given. We demonstrate an optical reading technique which uses an atomic force microscope (AFM) and a micromechanically released membrane. Memory optical storage methods involving the AFM or the scanning tunneling microscope (STM) are desirable for their potential applications in extremely high density memory data bit arrays. The densities of bits written using scanning probe microscope tips are more than two orders of magnitude greater than that available with state-of-the-art commercial optical techniques.

Tunable long wavelength LED using wafer bonding and micromachining technologies

We have combined the technologies of wafer bonding and micromachining to produce a tunable LED at 1.51 /spl mu/m. The bonding technique allows us to combine an InP-based multiple quantum well structure with a GaAs-based Bragg mirror for higher reflectivity than traditional InP-based mirrors. Micromachining techniques then allow us to suspend a mirror above the surface of the substrate to provide a tuning method for the LED.

A generic monolithically integrated micromechanic optic sensor (MIMOS)

This paper addresses an innovative optical scheme to detect ultrafine motions of micromechanical structures, as a generic design for a whole class of sensors including accelerometers, gyroscopes, position sensors, etc.. We fabricated a monolithically integrated micromechanic optic sensor (MIMOS) on a Si substrate. The device consists of two superimposing gratings with a small angle and an array of photodetectors.