K. Hane

Optical scanner on a three-dimensional microoptical bench

A three-dimensional (3-D) microoptical bench prepared using bulk micromachining is constructed demonstrating a compact optical setup. Prealigned microstructures with space for mounting bulk elements are prepared. A 3-D photolithographic technique is applied with good repeatability using an originally developed resist spray-coating system. Films grown by low-pressure chemical-vapor deposition (LPCVD) are used as construction layers combining with 3-D bulk structures. A skew micromirror at the free end of a thermally actuated cantilever is fabricated facing to a laser diode chip. An optical-scan angle of more than 30/spl deg/ and a cutoff frequency of 100 Hz are obtained.

High-efficiency light-emitting column-crystallized InGaN∕GaN quantum-well flower structure on micropillared Si substrate

Column-crystallized InGaN∕GaN quantum-well flower structure was deposited on pillared Si (111) substrate. Dotted GaN nuclei grew along the direction of the coming Ga and N atoms, forming arrays of InGaN∕GaN quantum-well flower structure. Raman spectra measurement demonstrated that these crystals were fully relaxed. Photoluminescence measurement showed a room temperature peak position of 556nm and two peak positions of 400 and 549nm at low temperature. Hg lamp excited photoluminescence demonstrated a clear fluorescence distribution from the low to the top part of the flower structure and much stronger emission compared with the quantum-well crystals on the flat Si substrate.

Precision optical displacement sensor based on ultra-thin film photodiode type optical interferometers

The design and fabrication of our compact precision optical displacement sensor (PODS) are based on the newly developed ultra-thin film photodiode with its active layer thinner than a half of the incident light wavelength. In this paper, a detailed description of the principle, design, fabrication process and performance of PODS for application in both smooth and rough surfaces will be given.

2-axis MEMS scanner for a laser range finder

A moving-magnet-type 2-axis MEMS scanner with a rotation angle detector has been developed. The fabricated MEMS scanner demonstrated a raster scan and 2-axis rotation angles detection with one Hall sensor.

XY-Stage for Scanning Media for Optical Data Storage

XY-stage driven by the electrostatic comb-drive actuator is fabricated realizing long displacement. The actuator is fabricated in one layer of silicon-on-insulator (SOI) wafer, and the media plate is in the other layer. The raster scanning of the plate is realized maintaining orthogonal xy-directions. The fast scanning is y-axis. Two 820times950 mum2-size media plates are driven at the opposite y directions canceling the inertia force. The static maximum displacements are 110 mum (geometrical limit) along x-axis and 90 mum along y-axis. At the resonance, 115 mum (geometrical limit) is obtained along y-axis

Silicon microring resonator connected with submicorn comb actuator

A 500 nm wide 260 nm thick 63.4 mum long silicon microring waveguide was suspended in air by connecting to a comb actuator with the low-loss suspension arms. The airgap between the microring and the input/output waveguides was adjusted by a voltage applied to the comb actuator to vary the coupling efficiency. Transmittance from the input to the drop waveguides was varied from 0% at the gap of 750 nm to 50% maximum value (about 30 dB) at the voltages from 0 V to 28 V. Under the drop condition, the bandwidth of the drop signal was 0.5 nm, corresponding to the Q-value of 3100.

Growth of GaN Quantum Well Film on Si Substrate and Its Application to a GaN-Si Hybrid Lightning Device

We propose here a new light source with a light beam steering mechanism. The direction of the light beam emitted from an array of the light emitting diodes (LEDs) can be changed by a micro-actuator. The proposed device is monolithically composed of the GaN LEDs and Si MEMS structure. Basic researches on the growth of GaN crystals on Si substrate were carried out. Quantum well (QW) structures consisting of InGaN/GaN crystals were formed with a buffer layer between the GaN crystal and Si substrate. Column-like GaN crystals with the QWs were grown. Due to the column structure and the buffer layer, the crystals were relaxed enough to obtain strong photoluminescence. From Si substrate with GaN crystal, a micro-stage with comb actuators on which the InGaN/GaN QW film is patterned has also been fabricated

Micro-encoder using image obtained by ball lens assembled inside wafer

An absolute micro-encoder based on the code imaging is developed. The ball lens (phi300 mum) is assembled inside the cavity between the pyrex glass lid and suspensions in the handling Si layer of the SOI wafer. The photodiode array is prepared in the device Si layer. The image of the scale is incident on the backside of the photodiodes. The electrical wiring to photodiodes does not disturb the optics. The current signal shows the sufficient contrast for resolving the maximum length code having the minimum line width of 13.6 mum

Confocal laser displacement sensor using MEMS varifocal mirror

A confocal laser displacement sensor using a micro-machined varifocal mirror is reported. The focal length modulation is a key function for the sensor. The measurement speed and range depend on the mechanism. In this study, we propose to use the micro-machined varifocal mirror for the mechanism of the focal length modulation in the confocal displacement sensor. The electrostatically actuated varifocal mirror made by silicon was used. The working distance of the displacement sensor is designed to be 31 mm. The measurement range at 7 kHz is 310 μm. The linearity in the full scale range is from −1.5% to 0.85%.

GaN microring waveguide bonded to Si substrate by polymer

Hybrid integration of GaN and Si photonic devices is promising. Using a polymer bonding technique, GaN microring resonators are fabricated on Si substrate. Transmission characteristics of the GaN microring is measured.