Programmable Phase Research Articles

Can a Programmable Phase Plate Serve as an Aberration Corrector in the Transmission Electron Microscope (TEM)?

Abstract Current progress in programmable electrostatic phase plates raises questions about their usefulness for specific applications. Here, we explore different designs for such phase plates with the specific goal of correcting spherical aberration in the transmission electron microscope (TEM). We numerically investigate whether a phase plate could provide down to 1 Ångström spatial resolution on a conventional uncorrected TEM. Different design aspects (fill factor, pixel pattern, symmetry) were evaluated to understand their effect on the electron probe size and current density. Some proposed designs show a probe size (d50) down to 0.66 Å, proving that it should be possible to correct spherical aberration well past the 1 Å limit using a programmable phase plate consisting of an array of electrostatic phase-shifting elements.

Active focal-plane coronagraphy with liquid-crystal spatial-light modulators: broadband contrast performance in the visible.

The technological progress in spatial-light modulator (SLM) technology has made it possible to use those devices as programmable active focal-plane phase coronagraphic masks, opening the door to novel versatile and adaptive high-contrast imaging observation strategies. However, the scalar nature of the SLM-induced phase response is a potential hurdle when applying the approach to wideband light, as is typical in astronomical imaging. For the first time, to our knowledge, we present laboratory results with broadband light (up to ∼12% bandwidth) for two commercially available SLM devices used as active focal-plane phase masks in the visible regime (640 nm). It is shown that under ideal or realistic telescope aperture conditions, the contrast performance is negligibly affected in this bandwidth regime, reaching a sufficient level for ground-based high-contrast imaging, which is typically dominated by atmospheric residuals.

A 32–40 GHz 7-bit Bi-Directional Phase Shifter With 0.36 dB/1.6° RMS Magnitude/Phase Errors for Phased Array Systems

This paper presents a digitally programmable bi-directional 7-bit passive phase shifter in a 65 nm CMOS technology. The core of this passive vector-synthesized phase shifter is a hybrid quadrature generator (HQG), an interstage matching network, and a passive vector modulator (PVM). This work proposes a high coupling-factor-based quadrature generator design methodology and demonstrates it with a compact vertical transformer. The interstage matching network between HQG and PVM is proposed to release the bandwidth bottleneck and achieve a 34% fractional frequency bandwidth. Two 6-bit X-type attenuators in the I and Q path form a high-resolution 12-bit controlling word. In 32–40 GHz, this 7-bit 360° phase shifter achieves a measured 2.8° step with 0.45-1.6° RMS phase error and 0.2-0.36 dB RMS magnitude error. With the broadband technique, its 3-dB bandwidth reaches 30.2-42.7 GHz with a 2.8° RMS phase error. Its in-band 1-dB compression point is 10.2 dBm. With the proposed compact HQG and PVM, this mm-wave passive phase shifter only occupies <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$220\times 630\,\,\mu \text{m}^{2}$ </tex-math></inline-formula> and has no power consumption.

A 4–10 GHz Programmable CMOS Vector-Sum Phase Shifter for a Two-Channel Transmitter

A 6-bit full-span programmable vector-sum phase shifter was presented in this brief. A transformer-based matching network is used to match the PPF-based I/Q generator to the variable gain amplifier-based vector-modulator (VGA-based VM), which eliminates the performance degradation due to impedance mismatch. The proposed phase shifter integrated in a two-channel transmitter was implemented in a 180-nm CMOS process. A program-assisted method was used to select the desired 6-bit (64) phase states from the total 4096 measured states of the chip, to realize a highly accurate phase tuning. The center frequency of the phase tuning can be set in the program, for different operation frequency points. An ultra-low root-mean-square (rms) phase/gain error less than 0.5°/0.15 dB are obtained at corresponding single frequency points. Moreover, a “band” mode is available as well, and rms phase/gain errors less than 2.25°/0.56 dB and 1.1°/0.32 dB are obtained at 4–10 GHz and 5.5-7.5 GHz, respectively.

A 64-Gb/s PAM-4 Receiver With Transition-Weighted Phase Detector

This brief presents a programmable phase detector (PD) for the Baud-rate clock and data recovery (CDR) in four-level pulse amplitude modulation (PAM-4) quarter-rate receiver, using a transition weighted gain (TWG) technique. By assigning a different gain to the phase detection for each data-level transition, the TWG-based CDR (TWG-CDR) achieves stable operation of the CDR and jitter tracking. An optimal phase detection transfer characteristic is obtained by assigning the highest weight on the 1-level data transition and the lowest on the 3-level transition. The proposed CDR fabricated in 40 nm CMOS technology performs at 64-Gb/s in PAM-4. The measured jitter tolerance (JTOL) shows that the TWG-CDR improves the horizontal eye opening margin compared to the sign-sign Mueller-Müller CDR. The TWG-CDR tested around a 6dB loss channel achieves a BER less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−11</sup> and energy efficiency of 2.37 pJ/b.

Design of an active a 5- bit digitally programmable phase shifter for hybrid antenna beamformers

This paper presents the design of a new 5-bit digitally programmable phase shifter using CMOS technology of 65 nm, for its use in hybrid antenna beamformers opperating at the part of the K-band destinated to SATCOM communications. Simulation results are compared with previously reported alternatives.

Uxua Esteban - Design of an active a 5-bit digitally programmable phase shifter for hybrid antenna beamformers

Design of an active a 5-bit digitally programmable phase shifter for hybrid antenna beamformers

Idealized four-wave mixing dynamics in a nonlinear Schrödinger equation fiber system

The observation of ideal four-wave mixing dynamics is notoriously difficult to implement experimentally due to the generation of higher-order sidebands and optical loss, which limit the potential interaction distance. Here, we overcome this problem with an experimental technique that uses programmable phase and amplitude shaping to iterate the wave mixing initial conditions injected into an optical fiber. This extends the effective propagation distance by two orders of magnitude, allowing idealized Kerr-driven dynamics to be seen over 50 km of fiber using only one short fiber segment of 500 m. Our experiments reveal the full phase space topology, showing characteristic features of multiple Fermi–Pasta–Ulam recurrence, stationary wave existence, and the system separatrix representing the boundary between two distinct regimes of spatiotemporal evolution. Experiments are in excellent quantitative agreement with numerical solutions of the differential equation system describing the wave evolution. This experimental approach can be readily adapted to study other wave mixing and nonlinear propagation phenomena in optics.

Multi-Band Operation of Flat-Top Supercontinuum Laser Sources With Programmable Repetition Rate up to 50 GHz

We present ultra-broadband flat-topped supercontinuum laser sources with programmable repetition rate, spectral bandwidth, and wavelength regime. Supercontinuum sources with multiband coverage can be achieved by merging high-repetition-rate electro-optic frequency comb techniques with optical line-by-line pulse shaping. Because nonlinear broadening in the optical wave-breaking regime does not provide the required flatness and spectral bandwidth to the comb-based sources, we iteratively manipulate the spectral amplitude and phase of the optical pulse shaper. We implemented here a smooth flat-topped supercontinuum with a 97 nm bandwidth at 10 dB and programmable repetition rate up to 50 GHz by applying a bandwidth-limited quasi-super-Gaussian apodised pulse train to a highly nonlinear medium with programmable super-Gaussian and phase coefficients. This work opens new possibilities for generating robust and coherent multiple optical carriers with further C-bands in optical networks. We believe that the supercontinuum sources based on electro-optic frequency comb and pulse shaping techniques enable the provision of coherent flat-topped optical sources, at least from the L- to S-band with a programmable repetition rate and spectral bandwidth.

Modularizable Liquid-Crystal-Based Open Surfaces Enable Programmable Chemical Transport and Feeding using Liquid Droplets.

Droplet-based miniature reactors have attracted interest in both fundamental studies, for the unique reaction kinetics they enable, and applications in bio-diagnosis and material synthesis. However, the precise and automatic feeding of chemicals, important for the delicate reactions in these miniaturized chemical reactors, either requires complex, high-cost microfluidic devices or lacks the capability to maintain a pinning-free droplet movement. Here, the design and synthesis of a new class of liquid crystal (LC)-based open surfaces, which enable a controlled chemical release via a programmable LC phase transition without sacrificing the free transport of the droplets, are reported. It is demonstrated that their intrinsic slipperiness and self-healing properties enable a modularizable assembly of LC surfaces that can be loaded with different chemicals to achieve a wide range of chemical reactions carried out within the droplets, including sequential and parallel chemical reactions, crystal growth, and polymer synthesis. Finally, an LC-based chemical feeding device is developed that can automatically control the release of chemicals to direct the simultaneous differentiation of human induced pluripotent stem cells into endothelial progenitor cells and cardiomyocytes. Overall, these LC surfaces exhibit desirable levels of automation, responsiveness, and controllability for use in miniature droplet carriers and reactors.

Programmable hyperbolic metamaterial-supported reflection modulator

We report a programmable phase change medium-based hyperbolic metamaterial (HMM) with emphasis on the optical response characterized by adjusting the electrical constants and/or structural parameters (such as thicknesses and/or filling fraction) of the constituent materials. The investigation reveals broad area of the type I HMM in the visible regime for the device comprising silver and stibnite mediums. The angle- and polarization-insensitive properties of the configuration demonstrate an in-band rejection of over −75 dB, tunable in the range of 0.5723 to 0.639 μm, and an 8-bit encoding bandwidth of 12 nm. Also, the study yields two distinct modulation mechanisms at the incidence angle of 62 deg, viz. a Brewster modulator in the UV regime (which solely depends on the incidence obliquity) and an angle-insensitive reflection modulator in the visible regime—the features that are programmable according to the thermal ambience.

Direct construction of an optical linear transform and its application on optical complex data generation.

Optical computing technique has emerged as a promising platform for highly parallel data processing. In most optical computing architectures, optical linear transform is the basic composition, which is commonly designed by the established deep learning-based methods or general-purpose optimizers. There still lacks in-depth study to construct a solver targeted at optical linear transform applications. In this work, we propose a new algorithm that solves the transformation matrix of a linear optical system consisting of cascaded phase masks directly and show that its efficiency is significantly higher than those common solvers. As a direct application of this method, we can create target array of optical beams even with a single layer of phase mask in the experiment. The amplitude and phase of each beam in the array can be controlled independently without affecting each other. The optical system requires only one light source and one programmable phase mask. This setup can be readily incorporated into most current optical computing configurations. Our method may find broad applications in classic and quantum optical information processing.

Programmable photon pair source

Photon pairs produced by the pulse-pumped nonlinear parametric processes have been a workhorse of quantum information science (QIS). Engineering the spectral property of quantum states is crucial for practical QIS applications. However, photon pairs with desirable spectral properties are currently achieved with specially engineered optical hardware but with severely limited flexibility in tuning the spectral properties of the sources. Here, we demonstrate a spectrally programmable photon pair source by exploiting a two-stage nonlinear interferometer scheme with a computer-controlled phase device. The phase-control device can introduce phase shifts for spectral engineering by a programmable phase function that can be arbitrarily defined. When the phase function is properly designed, the output spectrum of the source can be freely customized and changed without replacing any hardware component in the system. Using this approach, we are able to program photon pairs with factorable positively correlated and negatively correlated spectra. In addition, we also realize a source of multi-dimensional three-channel spectrally factorable photon pairs. Our investigation provides a flexible and powerful new approach for engineering the mode profile of photon pairs and should find wide applications in QIS.

Design of a Digitally Programmable Phase Shifter for Active Antenna Arrays

This paper presents the design of a new phase shifter using CMOS technology of 65 nm, for its use in arrays of antennas opperating at the millimeter band (24 GHz). It is an active phase shifter digitally programmable using a 4-bit word.

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.

Simultaneous turbulence mitigation and channel demultiplexing using a single multi-plane light convertor for a free-space optical link with two 100-Gbit/s OAM channels

A single multi-plane light convertor (MPLC) is applied to simultaneously mitigate turbulence-induced crosstalk and demultiplex two orbital angular momentum (OAM) multiplexed channels for a free-space optical link. Comprised of six programmable phase planes, the MPLC is placed at the receiver side for turbulence mitigation and channel demultiplexing. Propagating through the cascaded phase planes, two coaxial turbulence-distorted OAM beams each carrying one data channel are shaped and sorted into two differently positioned Gaussian beams with low inter-channel crosstalk. As an experimental demonstration, one MPLC adaptively mitigates the turbulence-induced crosstalk by up to 26 dB for two OAM-multiplexed channels (ℓ = {−1, +2}). Two 100-Gbit/s quadrature-phase-shift-keying (QPSK) channels are recovered with an up-to-1.5-dB optical signal-to-noise ratio (OSNR) penalty under one turbulence realization.

A Wearable Ultrasonic Neurostimulator - Part I: A 1D CMUT Phased Array System for Chronic Implantation in Small Animals.

In this work, we present a wireless ultrasonic neurostimulator, aiming at a truly wearable device for brain stimulation in small behaving animals. A 1D 5-MHz capacitive micromachined ultrasonic transducer (CMUT) array is adopted to implement a head-mounted stimulation device. A companion ASIC with integrated 16-channel high-voltage (60-V) pulsers was designed to drive the 16-element CMUT array. The ASIC can generate excitation signals with element-wise programmable phases and amplitudes: 1) programmable sixteen phase delays enable electrical beam focusing and steering, and 2) four scalable amplitude levels, implemented with a symmetric pulse-width-modulation technique, are sufficient to suppress unwanted sidelobes (apodization). The ASIC was fabricated in the TSMC 0.18- μm HV BCD process within a die size of 2.5 × 2.5 mm2. To realize a completely wearable system, the system is partitioned into two parts for weight distribution: 1) a head unit (17 mg) with the CMUT array, 2) a backpack unit (19.7 g) that includes electronics such as the ASIC, a power management unit, a wireless module, and a battery. Hydrophone-based acoustic measurements were performed to demonstrate the focusing and beam steering capability of the proposed system. Also, we achieved a peak-to-peak pressure of 2.1 MPa, which corresponds to a spatial peak pulse average intensity ( ISPPA) of 33.5 W/cm2, with a lateral full width at half maximum (FWHM) of 0.6 mm at a depth of 3.5 mm.

Phased-array antennas using novel PSoC-controlled phase shifters for wireless applications

AbstractThe paper proposes a system consisting of novel programmable system on chip (PSoC)-controlled phase shifters which in turn guides the beam of an antenna array attached to it. Four antennae forming an array receive individual inputs from the programmable phase shifters (IC 2484). The input to the PSoC-based phase shifter is provided from an optimized 1:4 Wilkinson power divider. The antenna consists of an inverted L-shaped dipole on the front and two mirrored inverted L-shaped dipoles mounted on a rectangular conductive structure on the back which resonates in the ISM/Wi-Fi band (2.40–2.48 GHz). The power divider is designed to provide the feed to the phase shifter using a beamforming network while ensuring good isolation among the ports. The power divider has measured S11, S21, S31, S41, and S51 to be −14, −6.25, −6.31, −6.28, and −6.31 dB, respectively at a frequency of 2.45 GHz. The ingenious controller is designed in-house using a PSoC microcontroller to regulate the control voltage of individual phase shifter IC and generate progressive phase shifts. To validate the calibration of the in-house designed control circuit, the phased array is simulated using $s_p^2$ touchstone file of IC 2484. This designed control circuit exhibits low insertion loss close to −8.5 dB, voltage standing wave ratio of 1.58:1, and reflection coefficient (S11) is −14.36 dB at 2.45 GHz. Low insertion loss variations confirm that the phased-array antenna gives equal amplitude and phase. The beamforming radiation patterns for different scan angles (30, 60, and 90°) for experimental and simulated phased-array antenna are matched accurately showing the accuracy of the control circuit designed. The average experimental and simulated gain is 13.03 and 13.48 dBi respectively. The in-house designed controller overcomes the primary limitations associated with the present electromechanical phased array such as cost weight, size, power consumption, and complexity in design which limits the use of a phased array to military applications only. The current study with novel design and enhanced performance makes the system worthy of the practical use of phased-array antennas for common society at large.

Innovative Development of Programmable Phase Change Materials and Their Exemplary Application

The research project Fraunhofer Cluster of Excellence “Programmable Materials” aims to develop new materials that can change their properties according to defined boundaries. This article describes the development and use of a novel programmable phase change material (PCM) for latent heat storage applications. At the moment, these PCMs have a programmable trigger mechanism incorporated that activates the crystallization of the material as a reaction to a defined stimulus so that the stored heat is released. In future development stages, programmability is to be integrated on the material level. The latent heat storage that is based on PCMs can be recharged by using the energy of the sun. As an example, for a possible application of such a material, the use of a novel programmable PCM in greenhouses to support heating energy reduction or to reduce the risk of frost is explained. Using the hygrothermal simulation tool WUFI® Plus, the effects in greenhouse constructions without and with commercially available or novel programmable PCMs are calculated and presented in the present article. The calculations are based on the material data of calcium chloride hexahydrate (CaCl2-6H2O), as this material serves as a basic material for the development of programmable PCM compositions. The results of the simulations show a positive impact on the indoor temperatures in greenhouses in view of the risk of frost and the reduction of heating energy. Thus, the vegetation period can be extended in combination with a lower energy load. By an eligible actuation mechanism, an inherent material system for temperature control can be created.

The Chronotopic™ System for Pulsatile and Colonic Delivery of Active Molecules in the Era of Precision Medicine: Feasibility by 3D Printing via Fused Deposition Modeling (FDM).

The pulsatile-release Chronotopic™ system was conceived of as a drug-containing core surrounded by a coat made of swellable/soluble hydrophilic polymers, the latter being able to provide a programmable lag phase prior to drug liberation. This system was also proposed in a colon-targeting configuration, entailing a gastroresistant film to prevent early interaction of the inner coat with gastric fluids and enabling the attainment of a lag phase matching the small intestinal transit time. Over the years, various multiple-step manufacturing processes have been tested for the fabrication of the Chronotopic™ system in both its configurations. This work focused on the evaluation of 3D printing by fused deposition modeling in view of its potential towards product personalization, on demand one-step manufacturing and efficient scale down of batches. The feasibility of each part of the Chronotopic™ system was independently investigated starting from in-house made filaments, characterizing the resulting specimens for physico-technological and performance characteristics. The printing parameters identified as suitable during the set-up phase were then used to fabricate prototypes either in a single step for the pulsatile configuration or following two different fabrication approaches for the colon-targeting one.