Measured Switching Time Research Articles

A liquid crystal stackable phased array to achieve fast and precise nonmechanical laser beam deflection

In this study, a novel liquid crystal (LC) stackable optical phased array (SOPA) for fine tracking with fast and precise beam steering is proposed. The SOPA was composed of multiple layers of sliced phase shifters (SPSs). Each SPS had two parts for loading different voltages to form programmable phase steps. All LC materials were compatible with this architecture, including blue-phase, polymer network, and ferroelectric LCs. To verify and evaluate the properties of this SOPA scheme, a three-layered SOPA prototype was designed and fabricated according to the standard processing of LC devices. A couple of steering experiments, with steering angles ranging from −100 to 100 μrad in a step of 10 μrad, were performed. The steering efficiency recorded in all the experiments exceeded 90%. All the measured switching time of angle-to-angle were less than 10 ms. Herein, the fastest switching time reported was only 1.52 ms.

Improved Design of Ohmic RF MEMS Switch for Reduced Fabrication Steps

RF MEMS ohmic switches are prone to stiction and contact degradation. In literature, bumps are made at the contact area to reduce stiction with additional fabrication steps. In this article, ohmic switch based on cantilever configuration is developed without using any additional step. The switch structure is modified to improve its mechanical parameters, such as pull-in voltage and switching speed. The measured switching time of the switch is $1.8~\mu \text{s}$ . A footprint of the developed single pole single throw (SPST) switch is 0.9 mm2. The insertion loss and isolation of the SPST switch are better than 0.8 and 20 dB, respectively. The switch has a wide bandwidth of 10 GHz (dc to 10 GHz). The switch has completed 725 million hot cycles at 1-dBm power.

Picosecond-Range Avalanche Switching of Bulk Semiconductors Triggered by Steep High-Voltage Pulses

Experimental observation and numerical simulations of sub-nanosecond avalanche switching of Si and ZnSe bulk semiconductor structures initiated by high-voltage pulses with steep (dU / dt > 10 kV/ns) ramp are reported. The measured switching time is ~100ps. The switching is sustainable and repetitive and has negligible jitter. Comparison of the experimental and numerical results suggests that after switching, the whole volume of the structure is uniformly filled with nonequilibrium electron-hole plasma.

A Quasi-Absorptive Microwave Resonant Plasma Switch for High-Power Applications

In this paper, a new plasma-based high-power microwave single-pole single-throw (SPST) switch is introduced and experimentally investigated. This switch is composed of a two-pole evanescent-mode cavity structure loaded with two gas discharge tubes over its posts. Since part of the energy required for the tubes ignition is supplied by the incoming electromagnetic waves, the switching mechanism is quasi absorptive. A prototype SPST switch at the frequency range of 2.8–3.9 GHz is fabricated and successfully examined over the power range of 2–20 W. With less than 1 dB of insertion loss, the ON/OFF isolation varies from 13 to 22 dB, depending on the input power. The measured switching time was on the order of tens of nanoseconds, and the input third-order intercept point that characterizes linearity was +53 dBm. Upon ignition, the microwave-sustained plasma in the switch operates in the $\alpha $ -discharge regime, ensuring that the switch performance is quite stable, with no degradation after long periods of operation.

Suppression of thermal wavelength drift in widely tunable DS-DBR laser for fast channel-to-channel switching.

We present a simple and effective method for suppressing thermally induced wavelength drift in a widely tunable digital supermode distributed Bragg reflector (DS-DBR) laser monolithically integrated with a semiconductor optical amplifier (SOA). For fast thermal compensation, pre-compensatory currents are injected into the gain medium section of the DS-DBR laser and the SOA. This method can be easily applied to existing commercial tunable lasers, since it is implemented without any modification to manufacturing process. Experimental results exhibit that wavelength stability is noticeably improved to ± 0.01 nm. We also experimentally demonstrate a fast channel-to-channel switching in a wavelength-routed optical switching system employing a 90 × 90 arrayed waveguide grating router (AWGR). The measured switching time is less than 0.81 µs.

Switching time of electrical tuning of permeability in strain-mediated multiferroic heterostructures

The switching time of the electrically tunable permeability of the NiFeTa/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 multiferroic material was characterized by using a Vector Network Analyzer and a pulse generator. The measured switching time for the permeability to be electrically tuned from the initial value to the final value upon the change of the applied electrical field is 0.15 s, which is independent of the magnitude of the electrical field and the measured frequency. The result is verified by the measurement of the time response permeability under a series of pulses with different pulse widths. It was found that for the cases of the pulse width smaller than the switching time, the rise time of the permeability response pulse is the same as the pulse width and the pulse height of the response permeability is linearly dependent on the pulse width. It is suggested that the temporal relaxation process of the interface arising from the strain transfer delay time between the film and the substrate plays a dominant role in the contribution of the total switching time of the material.

Surface-Micromachined Capacitive RF Switches With Low Actuation Voltage and Steady Contact

In this paper, we report fabrication and dynamic characterization of low-actuation-voltage capacitive radio frequency microelectromechanical systems (RF MEMS) switches with improved electromechanical performance. Electromechanical and electromagnetic modeling is used to modify the previously known geometries of switches and the number and size of holes in them to improve their overall dynamic characteristics. The switches are fabricated on a Pyrex glass substrate using a low-complexity four-mask surface micromachining process. These designs of MEMS switches require only 4.8-6.2 V as pull-in voltage. The dynamic behavior of these MEMS switches is investigated experimentally. Measured mechanical resonant frequency and quality factor are found to be in the range of 7.56-10.7 kHz and 1.1 to 1.2, respectively. Measured switching times for all the designs are 33-37 μs at their respective pull-in voltages. These switches show bounce-free switching during contact and fast settling after release. Two of the switch designs have insertion loss of less than 0.25 and 0.7 dB at 20 and 40 GHz, and isolation better than 30 dB. Close agreement between experimentally measured and simulation results demonstrates successful realization of fast-switching capacitive RF MEMS switches at low voltage. [2016-0152].

Large-scale broadband digital silicon photonic switches with vertical adiabatic couplers

Large-scale photonic switches are essential devices for energy- and cost-efficient optical communication networks in cloud and data-intensive computing. Silicon photonics is an attractive platform for high-density photonic integrated circuits with low manufacturing costs through the leveraging of existing advanced complementary metal-oxide-semiconductor processes. Many optical components such as lasers, modulators, splitters, and photodetectors have been successfully integrated on silicon; however, the quest for large-scale silicon photonic switches has remained elusive. Previous silicon photonic switches made of cascaded 1×2 or 2×2 building blocks have a limited port count (≤8×8) or excessive optical losses (>15 dB). Here, we present a 64×64 digital silicon photonic switch with a low on-chip insertion loss (3.7 dB) and broadband operation (300 nm). The measured switching time is 0.91 μs, and the extinction ratio is larger than 60 dB. The matrix switch with 4096 microelectromechanical-systems-actuated vertical adiabatic couplers has been integrated on a 8.6 mm×8.6 mm chip. To our knowledge this is the largest monolithic switch, and the largest silicon photonic integrated circuit, reported to date. The passive matrix architecture of our switch is fundamentally more scalable than that of multistage switches.

Thermal-electronic logic circuits: Scaling down

The thermal-electronic logic circuit (TELC) concept is a possible way to overcome the scaling down problems of the conventional CMOS integrated circuits, which have a very complex structure nowadays. The basic component of the TELC is the semiconductor–metal transition (SMT) switch, which is an extremely simple bulk type device. This work evaluates the effect of the scaling down on characteristics of the VO2 thermal-electronic switch. Different types (lateral and vertical) of VO2 resistors have been produced using focused ion beams and pulsed laser deposition. The measured switching time strongly correlates with the characteristic size of the device. The energy consumption (power-delay product) of the scaled-down switching device is estimated as a sum of the energy needed for heating the thermal diffusion length sized environment of the device, heating the device itself and the latent heat of phase transition of VO2.

Symmetric and Compact Single-Pole Multiple-Throw (SP7T, SP11T) RF MEMS Switches

This paper presents extremely compact single-pole multiple-throw radio frequency (RF) microelectromechanical system switches, SP7T and SP11T, based on a symmetric circular switch topology. The switch dimensions are 0.61 mm ×0.61 mm, which is smaller than typical CMOS Si-on-insulator switches. The SP7T and SP11T switches, which are insensitive to stress gradient effects, achieve simulated contact and restoring forces of 0.3-0.4 mN (per a switch) at 90-100 V. The SP7T and SP11T switches also achieve isolation levels of 50-19 dB and 50-17 dB, respectively, and insertion loss of 0.3-1.2 dB and 0.3-1.7 dB, respectively, at 0.1-10 GHz. The measured ON-resistance is 4.5-2.5 Ω at 75-100 V, respectively, in an open environment and limited by contact contamination. The measured switching time is 7-10 μs. Cold-switched reliability tests of SP7T and SP11T switches show greater than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> Hz with an RF power of 0.1-1 W, which is sufficient power handling capability for 3G and 4G systems.

Large-scale silicon photonic switches with movable directional couplers

Fast optical circuit switches (OCSs) with high port count offer reconfigurable bandwidth in optical networks and have the potential to significantly increase the performance and efficiency of modern datacenters. In this paper, we report on a new type of integrated OCS that combines silicon photonics with MEMS actuation. The switch is built on a 50×50 passive crossbar network with very low optical loss (0.04 dB/crossing). Efficient switching is achieved by a pair of directional couplers with moving waveguides and an actuation voltage of 14 V. 2500 MEMS-actuated directional coupler switches have been integrated with the crossbar network to form a strictly nonblocking 50×50 OCS on a 9 mm×9 mm chip. The measured switching time is 2.5 μs, and the extinction ratio is 26 dB. To our knowledge, this is the largest silicon photonic switch reported to date. The switch architecture is highly scalable because the light travels through only one active switching element, regardless of the size of the switch.

Noise-Induced Current Switching in Semiconductor Superlattices: Observation of Nonexponential Kinetics in a High-Dimensional System

We report on measurements of first-passage-time distributions associated with current switching in weakly coupled GaAs/AlAs superlattices driven by shot noise, a system that is both far from equilibrium and high dimensional. Static current-voltage (I-V) characteristics exhibit multiple current branches and bistability; precision, high-bandwidth current switching data are collected in response to steps in the applied voltage to final voltages V1 near the end of a current branch. For a range of V1 values, the measured switching times vary stochastically. At short times (≲10 μs), the switching time distributions decay exponentially, while at longer times the distributions develop nonexponential tails that follow an approximate power law over several decades. The power law decay behavior is attributed to the presence of multiple switching pathways, which may arise from small spatial variations in the superlattice growth parameters.

Low power consumption thermo‐optic switch based on DR1/PMMA

AbstractA new kind of thermo‐optic switch based on DR1/PMMA is proposed. This material has good cost‐performance, large thermo‐optic coefficient, and other advantages for electro‐optic devices because of the nonlinear chromophore DR1. Based on Mach‐Zehnder interferometer, this switch adopts the square waveguide structure and polymer silica hybrid configuration to adjust the optical field distribution for more thermo‐optic operation efficiency. A coplanar waveguide heater ensures the high frequency response of electrode and the ground electrode as a heat sink can prevent the thermo power accumulated. The total length of the device is 3.5 cm including the 1.5‐cm heater. The test results show that the extinction ratio is 21 dB, and the power consumption is less than 13 mW. The measured switching time is less than 0.9 ms. This work provides foundation for design and fabrication of electro‐optic and thermo‐optic hybrid integrated devices. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2163–2165, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26996

High-speed metal-insulator transition in vanadium dioxide films induced by an electrical pulsed voltage over nano-gap electrodes

We report the fabrication of VO2-based two terminal devices with ∼125-nm gaps between the two electrodes, using a simple, cost-effective method employing optical lithography and shadow evaporation. Current-voltage characteristics of the obtained devices show a main abrupt metal-insulator transition (MIT) in the VO2 film with voltage threshold values of several volts, followed by secondary MIT steps due to the nanostructured morphology of the layer. By applying to the two-terminal device a pulsed voltage over the MIT threshold, the measured switching time was as low as 4.5 ns and its value does not significantly change with device temperature, supporting the evidence of an electronically driven MIT.

Ultrafast Low-Loss 42–70 GHz Differential SPDT Switch in 0.35 $\mu$m SiGe Technology

This paper presents an ultrafast wideband low-loss single-pole double-throw (SPDT) differential switch in 0.35 m SiGe bipolar technology. The proposed topology adopting current-steering technique results in a total measured switching time of 75 ps , which suggests a maximum switching rate of 13 Gb/s, the fastest ever reported at V-band. In addition, the switch exhibits an insertion loss lower than 1.25 dB and an isolation higher than 18 dB from 42 GHz to 70 GHz.

Miniature MEMS Switches for RF Applications

This paper presents a new way to design MEMS (microelectromechanical system) metal contact switches for RF applications using miniature MEMS cantilevers. A single 25 × 25 μm switch is first demonstrated with a Au-to-Ru contact, Cu = 5 fF and Ron = 7 Ω at an actuation voltage of 55 V. The measured switching time is 2.2 μs and the release time is <;1 μs. The switch is robust to stress effects (residual and stress gradients) which increases its yield on large wafers. To reduce the effective switch resistance, 10-20 miniature RF MEMS switches have been placed in parallel and result in equal current division between the switches, an up-state capacitance of 30-65 fF and a down-state resistance of 1.4-1.5 Ω. Furthermore, 10-20 element back-to-back switch arrays are developed and result in a marked improvement in the reliability of the overall switching device. A series-shunt design is also demonstrated with greatly improved isolation. The device has a figure-of-merit of fc = 1/(2πRonCu) = 3.8 THz (RonCu = 42 fs).

Ultrafast electrical measurements of polarization dynamics in ferroelectric thin-film capacitors

We have developed a new approach to measure fast electrical signals during polarization switching in ferroelectric thin-film capacitors. This article describes a simple method for probing transient currents and voltages in a broad range of time scales from microseconds to hundreds of picoseconds. In order to test our approach, we probed polarization dynamics in commercial PbZr(0.2)Ti(0.8)O(3) ferroelectric capacitors in which the measured switching time was as fast as 1.7 ns.

Fully Integrated Switch-LNA Front-End IC Design in CMOS: A Systematic Approach for WLAN

A fully integrated front-end IC is demonstrated for 802.11b/g transceivers with integrated power amplifiers. The SP3T-LNA architecture integrates Bluetooth® functionality with transmit and receive for wireless LAN. The transmit switch achieves a P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> greater than 33.0 dBm at 2.5 GHz by employing a cross-biasing approach, transistor stacking and deep n-well process. Power handling techniques used for the switches and the associated performance tradeoffs are discussed. The measured noise figure of the LNA and the receive chain comprising both an LNA and a switch is 1.5 dB and 3.0 dB, respectively. The LNA achieves an IIP3 of 7.0 dBm while consuming 7.0 mA of current. The measured switching times are less than 350 ns. The front-end IC employs a 3.3 V supply and occupies 0.64 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in 0.18 μm bulk CMOS technology.

RF MEMS Capacitive Switches for Wide Temperature Range Applications Using a Standard Thin-Film Process

In this paper, the design, fabrication, and measurements of a capacitive RF microelectromechanical systems (RF MEMS) switch with very low sensitivity to thermal stress is presented. The switch is built by thin-film technology (0.8-μm Au) and shows <;50-mV/°C variation in the pull-down voltage at 25 °C-125 °C. The effects of the residual biaxial stress and stress gradients are studied in detail and the final switch design is very tolerant to a wide range of stress. The switch exhibits excellent RF and mechanical performances, and a capacitance ratio of about 51-57 (Cu = 54-66 fF, Cd = 3.1 - 3.4 pF) is reported. The mechanical resonant frequency and quality factor are fο = 105 - 115 kHz and Qm ≈ 8, respectively, with a measured switching time of about 3-3.8 μs. The applications areas are in low-loss RF MEMS, phase shifters, and reconfigurable networks.

MMI-MZI Polymer Thermo-Optic Switch With a High Refractive Index Contrast

The 2 x 2 MMI-MZI polymer thermo-optic switch in a high refractive index contrast (0.102) with a new structure design is realized. The fabrication was done using standard fabrication techniques such as coating, photolithography, and dry etching. A crosstalk level of dB has been achieved. Meanwhile, the extinction ratio of 28.6 dB has been achieved in this device. The polarization-dependent loss of 0.3 dB was measured at 1550 nm wavelength. In terms of wavelength dependency, the device shows a good performance within C-band wavelength with vacillation of the insertion loss value around 0.88 dB. The power consumption of 1.85 mW was measured to change the state of the switch from the cross to bar state. The measured switching time was 0.7 ms.