Chang-Hoon Oh

Electrostatic MEMS variable optical attenuator with rotating folded micromirror

The design and fabrication of an electrostatic MEMS variable optical attenuator (VOA) is described. The VOA is a reflection type with a folded micromirror actuated by a comb-drive actuator. The VOA is fabricated by a simple single-mask process. One photolithography and subsequent deep silicon reactive ion etching define all the microstructures of the VOA. The folded micromirror structure can reduce the overall size of the device by enabling the parallel alignment of an input fiber and an output fiber. Lensed fibers are used to maximize the coupling efficiency and the ease of assembly. The electrooptic characteristics and dynamic characteristics of fabricated VOA are measured. The initial insertion loss is 0.5 dB at 1550 nm and the maximum attenuation is 45 dB, respectively. The polarization dependent loss is measured to be 0.2 dB at 20-dB attenuation. The response time for maximum attenuation is less than 5 ms.

Integrated micro optical flying head with lens positioning actuator for small form factor data storage

An integrated MEMS optical flying head(OFH) is presented for a small form factor with high-density portable data storage. It is composed of a high numerical-aperture(NA) objective lens, a micro lens actuator for adjusting the position of the lens, an integrated air-bearing-slider(ABS), and an embedded magnetic-field-modulation(MFM) coil for magneto-optical recording. For adjusting the optimal focal length of the lens, a vertical comb-driven actuator and a parallel plate actuator are adopted. In addition, the area-optimized torsion spring is used for vertical actuation. The ABS structure and the double layer MFM coil are fabricated on a transparent substrate bonded to the silicon actuator. The overall size of the integrated MEMS OFH assembled with the high NA(0.85) objective lens is 3 mm? 1.6 mm? 0.5 mm(in length? width? thickness), which makes it suitable for a portable optical storage device.

A micro optical flying head for a PCMCIA-sized optical data storage

A micro optical flying head is presented for high-density PCMCIA-sized small form factor(SFF) optical data storage. It is composed of a high numerical-aperture(NA) objective lens, a micro lens actuator for adjusting the position of the lens to optimize the focal point to the recording layer of an optical disk, and an integrated air-bearing surface for flying over the spinning disk. The overall size of the fabricated micro optical flying head, assembled with high NA(0.85) objective lens, is as small as 3 mm/spl times/1.6 mm/spl times/0.5 mm(in length/spl times/width/spl times/thickness), which makes it suitable for the optical data storage device of mobile applications. Also, a basic operation of a PCMCIA type II optical drive prototype including the micro optical flying head is tested and presented.

Electrostatic MEMS variable optical attenuator with folded micromirror

A reflection type VOA with folded micromirror was designed and fabricated. The proposed mirror structure can reduce the size of device by parallel alignment of the two fibers. Lensed fibers are used for high coupling efficiency and ease of assembly. The initial insertion loss is about 0.6 dB and the maximum attenuation is about 30 dB. The switching time of the fabricated VOA is about 1 ms.

Ultra-Compact, Zero-Power Latching Linear Motor with Integrated Position Sensor for Portable Electronics

A large stroke, zero-power latching piezoelectrically actuated linear motor for portable electronics is designed, fabricated, and characterized. The actuator consists of a stator with a micromachined piezoelectric actuator and a metal guide with high permeability, and a permanent magnet rotor as well as an integrated position sensor. The completed actuator has a volume of 1 mm(w) times 3mm(t) times 5mm(l) with driving precision of 5 mum at a scalable full-stroke of 5 mum and a speed of 10 mm/s at 50 kHz of driving frequency. A built-in capacitive position sensor was able to determine the displacement of the rotor with a position sensitivity of 1 fF/mum.