The diversification of information and communication services has brought a variety of communication devices those incorporate radio communication circuits and require the circuit forming elements to be further microminiaturized and upgraded for higher radio frequency and broadband applications. In this trend, the key components are switching elements. Improving their performance is indispensable in order to realize next-generation information and communication services. RF MEMS technology, which combines 3-D micromachining technology and a high-frequency line design, is highly expected to provide a solution in this respect. The technology field has reached to a practical level and, in fact, a variety of key circuit elements are being proposed. In this paper, we propose a novel Single-Pole-Double-Throw (SPDT) RF MEMS switch design for RF signal applications in the 0.05-10GHz frequency. This new switch is actuated by electrostatic force and restoration force of spring for low power consumption. The Pyrex glass was used as base and cap substrates, and the single crystal silicon was used as movable parts. This device has extremely low insertion loss of -0.5 dB and a high isolation of -30 dB up to 10 GHz. The switch has compact dimensions of 2.8 x 4.8 x 0.9 mm with Chip Scale Package (CSP) structure. The packaging process with glass frit seal is applied to 4-inch processed wafer of RF MEMS switching devices.
We have developed a new type of scanning in-line shape-matching sensor with a miniature optical scanner based on a simple shape-matching algorithm. The sensor consists of a sensor head, a controller, an interface board and CPU. The sensor head, with dimensions of 30 by 40 by 40 mm<SUP>3</SUP>, consists of a miniature optical scanner, a laser diode with a collimator lens, a photo detector and an amplifier circuit. The controller consists of signal processing circuits which generate the scanning position information from the drive circuit of the scanner. The interface board inputs binary level signals to the CPU. The CPU is used for the calculation and judgement of the obtained data and for displaying the results of its output. The shape- matching is performed by comparing the obtained scanning data to the pre-inputted original data. The original data is inputted to the memory by scanning the beam on the correct status object. If both sets of data completely agree, it defines that detected object as equal to the original object. For comparison, the most typical parameter of the data, such as the pulse width or the number of pulses, is adapted. For example, in the case of size difference between screws, each pulse width of scanned data is changed. As a result, size detection can be achieved. As this scanning type sensor, not a CCD camera type, has features such as no external lighting, lower cost and miniature size, it could be applied in the area of simplified shape matching on the factor assembly line.
A highly miniaturized optical scanner integrated with a photo detector has been developed for miniaturization of scanning type of optical sensors. The scanner is fabricated by silicon micromachining technologies and is driven by a piezoelectric actuator. It is capable of two dimensional scanning and photo detection. The scanning angle is over 40 deg X 30 deg and the photo detecting sensitivity is 0.49 A/W for 680 nm wavelength light.
A novel micro focusing optical device controlled by a piezoelectric thin film micro actuator has been presented. This device is provided by bonding two micromachined substrates, which are a glass substrate integrated with a surface emitting light element and a micro Fresnel lens on each surface, and a silicon substrate with a diaphragm type of piezoelectric thin film actuator on it. The surface of the thin film is used as a movable reflection mirror. Focusing is performed by changing position of the mirror surface along the optical axis. In the case of applying the micro lens with 1.3 mm of diameter and 0.33 of N.A. to this focusing device and the thin film actuator capable of several micron displacement, focal point shifting of over 100 mm is obtained. Applying the device to optical senors such as a barcode reader, miniaturization of the light source and high resolution detecting for wide range could be possible.
Miniaturized opto-electronic and opto-electro-micromechanic hybrid integrated components are developed utilizing newly developed micro active semiconductor devices (e.g., laser diode, pin-point emission LED), micro optic passive devices (e.g., micro Fresnel lens, grating devices), and micro actuators. As a typical example, high-performance collimated and focused light sources, optical sensing devices, and two dimensional optical scanner are presented in detail.
A novel compact two dimensional optical sensor is proposed. The sensor consists of a piezoelectric actuator driven dual axis miniature optical scanner, a silicon photo diode, and a micro collimated light source with a micro Fresnel lens. By monitoring the beam intensity reflected from the object, the object position and the object size are determined, since the irradiated beam position is precisely identified by monitoring the phase of the applied ac voltage to the actuator. The sensing area as wide as 15 X 15 degrees is achieved with a simple configuration.
A novel super compact dual axis optical scanner composed of a miniature resonator driven by a piezoelectric actuator and a micro-collimated light source using a micro Fresnel lens has been developed. The scanner is able to scan an optical beam in two directions with a scanning angle of more than 20 degrees, and its dimensions are 30 mm X 20 mm X 20 mm.
A novel laser coupling module composed of a 1.3 micrometers single-mode fiber and a small laser package ((phi) equals 5.6 mm) which builds in a single thin microlens and a 0.78 micrometers emitting laser diode is proposed. A micro Fresnel lens with a high numerical aperture (0.45) and short focal length (0.65 mm) has been utilized for the first time as a laser-to-fiber coupling lens. The proposed laser coupling module measures about 2.8 mm between a laser facet and a fiber edge. The coupling efficiency of 23 in experiment is shown to be adequate for short- haul transmissions and fiber-to-the-home applications. Because all of the elements that compose the present module are able to be obtained at low prices, the design could reduce the cost of laser modules.
We have proposed a novel optical memory system, that is, multilayered optical storage system utilizing a micro Fresnel lens (MFL). The multiwavelength laser light through the MFL is focused on the point where the surface of each layer is laid, since the MFL focal length depends on the incident laser wavelength. We discussed and demonstrated the dependences of MFL's characteristics such as wavefront aberration, focal length, and focused beam spot size on the incident laser wavelength.
A supercompact microcollimated laser diode (MCLD) was developed without attaching any other external collimating lens. The MCLD consists of 780-nm quantum well laser diode dice and a microcollimating lens in the smallest commercially available laser package. In addition, the MCLD has high reliability against humidity and temperature variations, as all of the elements are assembled in the package filled with dry nitrogen gas. A short focal length micro Fresnel lens is used as the collimating lens to obtain the compact MCLD and narrow collimated laser beam. Additional details are provided on the micro Fresnel lens, the quantum well laser diode dice, and the microcollimated laser diode.
A novel static semiconductor laser digital scanner is proposed and demonstrated. The scanner consists of a monolithically integrated semiconductor laser array and an aspheric convex lens. Laser beams are deflected and scanned digitally by the convex lens with no mechanical action. Extremely high scanning speed can be achieved with this scanner
because the scanning speed is in principle limited only by semiconductor laser switching time. Scanning angles of the laser beam up to 400 were obtained for a 10-element semiconductor laser array. The array spacing is 300 p.m. and an aspheric convex lens with 4.5 mm focal length was used. Intensity profiles of the deflected beam coincide with calculations
using the ray tracing method.