Vertical Switch Research Articles

10.2172/1234568

Advanced switching devices with long lifetime will be critical components for Linear Transformer Drivers (LTDs) in next-generation accelerators. LTD designs employ high switch counts. With current gas switch technology at %7E10e3 shot life, a potential game-changer would be the development of a reliable low-impedance (%3C35nh) optically-triggered compact solid-state switch capable of switching 200kV and 50kA with 10e5 shotlife or better. Other applications of this technology, are pulse shaping programmable systems for dynamic material studies (Z-next, Genesis), efficient pulsed power systems for biofuel feedstock, short pulse (10 ns) accelerator designs for the Defense Threat Reduction Agency (DTRA), and sprytron replacements in NW firing sets. This LDRD project has succeeded in developing new optically-triggered photoconductive semiconductor switch (PCSS) designs that show great promise for scaling to modules capable of 200kV (DC) and 5kA current that can be stacked in parallel to achieve 100's of kA with 10e5 shot lifetime. . Executive Summary Advanced switching devices with long lifetime will be critical components for Linear Transformer Drivers (LTDs) in next-generation accelerators. LTD designs employ high switch counts. With current gas switch technology at %7E10e3 shot life, a potential game-changer would be the development of a reliable low-impedance (%3C35nh) optically-triggered compact solid-state switch capablemore » of switching 200kV and 50kA with 10e5 shotlife or better. Other applications of this technology, are pulse shaping programmable systems for dynamic material studies (Z-next, Genesis), efficient pulsed power systems for biofuel feedstock, short pulse (10 ns) accelerator designs for the Defense Threat Reduction Agency (DTRA), and sprytron replacements in NW firing sets. This LDRD project has succeeded in developing new optically-triggered photoconductive semiconductor switch (PCSS) designs that show great promise for scaling to modules capable of 200kV (DC) and 5kA current that can be stacked in parallel to achieve 100's of kA with 10e5 shot lifetime. The new vertical switch design configuration generates parallel filaments in the bulk GaAs (as opposed to just beneath the surface as in previous designs) to achieve breakdown fields close to the maximum for the bulk GaAs while operating in air, and with 2-D scalability of the number of current-sharing filaments. This design also may be highly compatible with 2-D VCSEL arrays for optical triggering. The demonstration of this design in this LDRD utilized standard thickness wafers to trigger 0.4kA at 35kV/cm (limited by 0.6mm wafer thickness), tested to 1e5 shots with no detectable degradation of switch performance. Higher fields, total current, and switching voltages would be achievable with thicker GaAs wafers. Another important application pursued in this LDRD is the use of PCSS for trigger generator applications. Conventional in-plane PCSS have achieved triggering of a 100kV sparkgap (Kinetech-type) switch of the type similar to switches being considered for accelerator upgrades. The trigger is also being developed for pulsed power for HPM applications that require miniaturization and robust performance in noisy compact environments. This has spawned new programs for developing this technology, including an STTR for VCSEL trigger laser integration, also pursuing other follow-on applications.« less

Push-pull fused vertical coupler switch

A single-electrode push-pull fused vertical coupler (PVC) switch using macroscopic crystal inversion symmetry is demonstrated. The anisotropic linear electrooptic effect in a zinc-blende crystal is used to achieve optical switching under 12-V reverse bias for a 6.9-mm-long FVC whose two guiding layers have different crystal symmetries. No switching is observed for the identical structure in which the two guiding layers have the same crystal symmetry.

Comparison of lateral and vertical switches for application as microrelays

This paper discusses the suitability of lateral and vertical switches for use as micorelays. These two types of switch are fabricated and tested and the advantages and disadvantages are outlined. The lateral motion switch consists of a single-crystalline silicon cantilever beam, which is made by a deep silicon etching process. Therefore the switch provides a high stiffness in the vertical axis, a high degree of design flexibility and a stress free structure, which is a main advantage of this type. The vertical motion switch is a multi-layer cantilever beam, which is distinguished by high isolation resistances and metallic contacts. Both types are candidates for microrelays; however the vertical switch seems more suited.

Fused vertical coupler switches

Electrical switching of fused vertical couplers (FVCs) is demonstrated. For a 3.5 mm long coupler, complete switching is observed at 3 V reverse bias. This low voltage is attributed to excess current induced internal heating and the thermo-optic effect. By changing the electrode design and reducing the excess current, a 6.9 mm long FVC with 12 V switching voltage is demonstrated.

Ultrashort low-loss optical multiquantum-well GaAs/GaAlAsvertical directional coupler switch

An optical GaAs/GaAlAs multiquantum-well vertical directional coupler switch with a device length of 85 µm is presented. At a wavelength of 854 nm the voltage necessary for switching was 5 V, associated with a transmission loss of only 2 dB in the switched state and an extinction ratio of greater than 10 dB. The device parameters were chosen so as to enable monolithic integration.

Low-voltage vertical directional coupler switch with suppressed electroabsorption

We have studied the performance of a vertical directional coupler in which a multiple quantum well and a bulk semiconductor material act as the cores of the two guides in two arms. The power output of the device is expected to be unaffected by the electroabsorption effect in a directional coupler based on quantum confined Stark effect even when operated very close to the excitonic absorption edge. The above principle is utilized in realizing low-voltage switching and almost equal power in bar and cross states in a multiple-quantum-well (MQW) vertical directional coupler. Our calculation for a vertical coupler composed of InGaAsP bulk and InGaAsP-InP MQWs show switching voltages comparable to that of a similar coupler composed of a more complex barrier reservoir and quantum well electron transfer (BRAQWET) structure, with a slightly lower value of power output.

Design of Vertical Directional Coupler Switch using Ferroelectric Liquid Crystal (FLC)

To decrease the switching length of a directional coupler switch and to make use of the electro-optic properties of FLC, we propose a novel vertical directional coupler switch using FLC and present the calculated results relevant to the design considerations. Because of the large birefringence of FLC, a very short switching length less than 40 μm is possible. Besides, a N x N switch is also proposed for practical applications.

A novel vertical Δκ directional coupler switch using liquid crystals

To decrease the switching length of the directional coupler switch and to use the advantages of the electro-optic properties of (LC's), we propose a novel vertical /spl Delta//spl kappa/ directional coupler switch using LC's and present the calculated results relevant to the design considerations. Because of the large birefringence of LC's, a very short switching length less than 60 /spl mu/m is possible. Besides, a N/spl times/N switch is also proposed for practical applications.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design considerations for vertical delta k directional coupler

Theoretical results relevant to the design of a vertical Delta kappa switch are presented. The principle of a Delta kappa switch is the modulation of the coupling length by the application of an even electrooptic perturbation on the coupling region. Power switching requires that Delta kappa L= pi /2. The initial state can be tuned electrically. The coupling length and the change with the index perturbation depend on many factors, such as the thickness and the refractive index of the coupling layer. Based on an analytic solution of the eigenmodes and eigenindices of the symmetric structure, the author clarifies many of these dependencies and obtains the relationship between the switching length required for power crossover and the available index change. The merits of the Delta kappa switch are discussed, and its efficiency is compared with that of the conventional Delta beta switch.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Transmission Self-Electro-Optic Effect Devices Based on Wannier-Stark Localization in a GaAs/AlAs Superlattice

We have studied optical switching of transmission-type self-electro-optic effect devices (SEEDs) based on Wannier-Stark localization (WSL) in a GaAs/AlAs superlattice (SL). Switching properties of both resister-biased and symmetric SEED are investigated as a function of operation wavelength. Clear optical bistability between two stable transmission states is obtained in the S-SEED configuration using the WSL. The detailed results of optical switching experiments are presented and explained in terms of a blue-shift mechanism of the optical absorption edge and an additional absorption mechanism due to spatially indirect Stark-ladder transitions in the SL. The SEED operation with a high transmission state is also demonstrated, and the advantages of the WSL are discussed for application to vertical transmission photonic switches.

Vertical multiple-quantum-well directional-coupler switch with low switching voltage

A novel device structure of the vertical directional-coupler optical switch with multiple quantum wells (MQWs) is proposed and fabricated. All the clad, guide, and separation layers are superlattices of Al/sub 0.3/Ga/sub 0.7/As and GaAs. This leads to a better control of the complete coupling length. The main feature of the proposed structure is that the refractive index modulation due to the quantum confined Stark effect (QCSE) is applied only to the undoped central region of the separation layer. It is found that this leads to reduction of the switching voltage. In an actual sample 138 mu m long, a switching voltage of 5 V has been obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A simple water flow sensor for electronic alarm systems

The use of a vertical float switch to indicate water flow is described. The unit can be used to provide ‘water on/water off’ signals for incorporation into a more general electronic alarm system and may be adapted for use in a research environment or in intensive fish production units. The device is of relatively low cost and is based on easily available components.

Power Switches: Some User Expectations and Preferences

Three brief studies were conducted by the IBM Boca Raton Human Factors department to investigate user expectations and preferences regarding power switches. In the first study, 24 IBM employees were surveyed by showing them a power supply with a paddle switch in front. The results indicated that if the power switch was mounted vertically, 100% of the sample expected UP to be ON. When the switch was mounted horizontally on the front, 25% of the sample expected LEFT to be ON, and the other 75% expected RIGHT to be ON. Ninety IBM employees participated in the second study. The purpose of this study was to investigate the way people expect a rocker switch to work when it is located on the side of the machine. Overall, 46% of the sample expected the switch AWAY from the operator to be ON, and 54% expected the switch TOWARD the operator to be ON. In the third study, 49 IBM employees responded to a mailed questionnaire, and 24 participants from a temporary employment agency completed the same questionnaire. The results for the six items were: 1. For UP/DOWN switch: UP=ON: 97%, DOWN=ON: 03% 2. For LEFT/RIGHT switch: LEFT=ON:29%, RIGHT=ON:71% 3. For AWAY/TOWARD switch: AWAY=ON:52%, TOWARD=ON:48% 4. Style preference (IBM Employees), (Agency Personnel) UP/DOWN:94% UP/DOWN:58% LEFT/RIGHT:02% LEFT/RIGHT:29% AWAY/TOWARD:04% AWAY/TOWARD:13% 5. Location preference: FRONT:72%, SIDE:25%, BACK:03% 6. Side preference: LEFT:10%, RIGHT:90% Since it appears that virtually 100% of users have the same expectation regarding the operation of a vertical power switch, designers should avoid using other power switch orientations. This is not a critical design issue, but it is better to design machines the way that users expect them to work.

Design considerations on high sensitivity mos area image sensor

AbstractBy clarifying the design approach of the photoelectric conversion of the two‐dimensional MOS solid‐state image sensor, a 320 × 244 element high responsivity MOS sensor has been fabricated and characterized. In the design of the photodiode design formulas for sensing capacity, responsivity and spectral response are presented and are in good agreement with the measurement. In order to suppress blooming without lowering the responsivity, the threshold voltage of the vertical switch transistor is raised and the photodiode whose n+‐diffusion layer of the signal wire is surrounded by the p+‐layer is proposed. In the horizontal switch transistor design, the signal reading residue is obtained and a simple formula describing the vertical resolution affected by the residue is also obtained.The main features of the MOS sensor developed by this design approach are: (1) high responsivity; (2) high resolution; and (3) strong blooming. The main characteristics are: for 1.4 μA saturation signal current, 71x saturation faceplate illumination (by Tungsten source) at 550 nm, the responsivity is 0.22 μA/μW, horizontal resolution is 240 TV lines, vertical resolution 190 TV lines and dissipation power is 30 mW.

Design and Application of EHV and UHV Vertical Break and Vertical Reach Switches

This paper discusses the design and application of EHV and ultrahigh-voltage (UHV) disconnecting switches. It reports on the results of comprehensive electrical and mechanical tests conducted on 765-kV vertical break and vertical reach switches. Electrical clearances, both line-to-ground and line-to-line, are reviewed. Finally, statements are made concerning 1100-kV switch designs in view of possible reduction in switching surge impulse levels from 2.1 to 1.5 pu.

Dielectric Tests on EHV Pantograph Switches

Tests were conducted on pantograph type disconnect switches to determine their dielectric characteristics. The data includes switching surge, impulse, and power frequency tests on insulations of 1300-, 1550-, and 1925-kV BIL, and open gaps of 130, 160, 180, and 200 inches. A comparison between the pantograph gap characteristics and various other vertical gaps, as well as vertical break switch gaps, is made. The effects of water resistivity on wet switching surge characteristics of the switch insulators was investigated for a 1550-kV BIL stack. The data is useful as a guide to the application of pantograph switches for EHV.