Experimental demonstration of a fast calibration method for integrated photonic circuits with cascaded phase shifters

With the development of research on integrated photonic quantum information processing,the integration level of the integrated quantum photonic circuits has been increasing continuously,which makes the calibration of the phase shifters on the chip increasingly difficult.For the calibration of multiple cascaded phase shifters that is not easy to be decoupled,the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters,making it impossible to calibrate a relatively large number of cascaded phase shifters.In this work,we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method,thus solving the calibration problem for multiple cascaded phase shifters.Specifically,we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.

Electro-Mechanical Phase Shifters Based on MEMS Structure

The aim of the study of phase shifter on MEMS （micro-electro-mechanical systems） structures was to minimize the dimensions of the design achievement. Also, the main task was to achieve the reliability and durability of the device. The calculation was based on the optimization technique （step by step） and the modeling of individual parts of the device, namely MEMS-keys that perform the main function--switching. The urgency of this problem is the development and study of one device as a universal, that is, automatically switches from two signals simultaneously. Designs are original and devises are the intellectual property of the authors. The program for modeling phase shifters Computer Simulation Technology Microwave Studio and its results are presented in the paper.

Thermo-optic phase shifters based on silicon-on-insulator platform: state-of-the-art and a review

Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one of the basic tuning devices,the thermo-optic phase shifter(TOPS)plays an important role in all these applications.A TOPS with the merits of easy fabrication,low power consumption,small thermal time constant,low insertion loss,small footprint,and low crosstalk,is needed to improve the performance and lower the cost of the above applications.To meet these demands,various TOPS have been proposed and experimentally demonstrated on different foundry platforms In this paper,we review the state-of-the-art of TOPS,including metal heater,doped silicon,silicide,with silicon substrate undercut for heat insulation,folded waveguide structure,and multi-pass waveguide structure.We further compare these TOPSs and propose the directions of the future developments on TOPS.

Application of SOl microring coupling modulation in microwave photonic phase shifters

Phase shifter is one of the key devices in microwave photonics. We report a silicon microring resonator with coupling modulation to realize microwave phase shift. With coupling tuning of the Mach-Zehnder interferometer （MZI） coupler to change the resonator from under-coupling to over-coupling, the device can realize a π phase shift on the incoming microwave signal with a frequency up to 25 GHz. The device can also realize 2.5π continuous phase tuning by manipulating the three DC bias voltages applied on the MZI coupler.

Single-Layer Symmetrical Full-Port Quasi-Absorptive Filtering Phase Shifter

In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.

基于5 μm厚向列相液晶的高效圆极化相控阵系统的设计、校准和实验验证

This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquidcrystal-based phased array(LCPA),including the design,over-the-air(OTA)in-array calibration,and experimental validation.The LCPA contains 16 phase-shifting radiating channels,each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter(LCPS)based on a loaded differential line structure.Thanks to its slow-wave properties,the LCPS exhibits a maximum phase-shifting range of more than 360°with a figure of merit of 78.3(°)·dB^(-1)based on a liquid crystal layer with a thickness of only 5μm.Furthermore,an automatic OTA calibration based on a state ergodic method is proposed,which enables the extraction of the phase-voltage curve of every individual LCPA channel.The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm,experimentally demonstrating a scanned circularly polarized beam from-40°to+40°with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB.The bandwidth of the LCPA,which satisfies the require-ments of port reflection(|S_(11)|)<-15 dB,an axial ratio(AR)<3 dB,beam squinting<3°,and a gain variation<2.2 dB,spans from 25.5 to 26.0 GHz.The total efficiency is about 34%,which represents a new state of the art.The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams,along with the systematic design and calibration methodology,holds potential promise for a variety of millimeter-wave applications.

A DC-to-32GHz 2Bit MEMS Phase Shifter

A two-bit phase shifter with distributed microelectromechanical system (MEMS) transmission line (DMTL) is developed,and a novel structure which be actuated by coplanar waveguide transmission line (CPW-actuation structure) is proposed,which can reduce the actuation voltage significantly.The measured result,with actuation voltage less than 20V,0°/20.1°/41.9°/68.2° phase shift and -1.2dB insert loss at 20GHz,is demonstrated,and insertion loss/return loss is better than -1.8dB/-11dB from DC to 32GHz.The experimental results highlight the potential of a low-loss and broadband digital MEMS phase shifter on a high-permittivity substrate.

High Energy Efficiency Dynamic Connected Hybrid Precoding for mm Wave Massive MIMO Systems

This paper considers a high energy efficiency dynamic connected(HEDC)structure,which promotes the practicability and reduces the power consumption of hybrid precoding system by lowresolution phase shifters(PSs).Based on the proposed structure,a new hybrid precoding algorithm is presented to optimize the energy efficiency,namely,HP-HEDC algorithm.Firstly,via a new defined effective optimal precoding matrix,the problem of optimizing the analog switch precoding matrix is formulated as a sparse representation problem.Thus,the optimal analog switch precoding matrix can be readily obtained by the branch-and-bound method.Then,the digital precoding matrix optimization problem is modeled as a dictionary update problem and solved by the method of optimal direction(MOD).Finally,the diagonal entries of the analog PS precoding matrix are optimized by exhaustive search independently since PS and antenna is one-to-one.Simulation results show that the HEDC structure enjoys low power consumption and satisfactory spectral efficiency.The proposed algorithm presents at least 50%energy efficiency improvement compared with other algorithms when the PS resolution is set as 3-bit.

Study on BSTO/MgO Ferroelectric Materials for Phase Shift Doped with Rare Earth Oxides

Barium strontium titanate/magnesia （BSTO/MgO） ferroeleetric materials for phase shift were prepared by traditional ceramic process-solid phase synthesis. The effects of various rare earth oxides of 0.5 % on dielectric behaviors of BSTO/MgO composites were studied in terms of permittivity, loss tangent and tunability both at low and high frequencies. The dielectric constant of Y2O3 and Er2O3 doped samples decreases from 160 to 120, and the microwave loss of La2O3 and Er2O3 doped samples decreases from 8.2 x 10-3 to 6.8 x 10-3. Only La203 increases the tunability of BSTO/MgO system, from 13.6% to 14.8%. For the La2O3 doped sample, the value of tunability is more than 14% with the external DC field 4000 V·mm^-1 and the microwave loss at 2.47 GHz is 6.77 ×10^-3 and, hence, it can basically meet the requirements of phase shifters working at microwave frequencies. The influence mechanism was discussed preliminarily.

A Uniform Reference Line Based Differential Phase Shifter with Wide Phase Range and Wide Bandwidth

To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidth and phase range deteriorates with the additional requirements considered.To solve this problem,a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line.According to the theoretical analysis on this basic element,the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property.With the predetermined parameters of the uniform reference line,only two parameters are required for the implementation of different differential phase shifts.This demonstrates the high simplicity of the proposed structure.For demonstration,an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure.The prototype was further fabricated and measured.Good agreement between simulation and measurement can be observed.The implemented phase shifter can provide a wide range of phase shifting values from 45°to 315°with reference to the uniform reference line over a relative bandwidth of 62.3%.

A monolithic distributed phase shifter based on right-handed nonlinear transmission lines at 30 GHz

The epitaxial material, device structure, and corresponding equivalent large signal circuit model of GaAs planar Schottky varactor diode are successfully developed to design and fabricate a monolithic phase shifter, which is based on right-handed nonlinear transmission lines and consists of a coplanar waveguide transmission line and periodically distributed GaAs planar Schottky varactor diode. The distributed-Schottky transmission-line-type phase shifter at a bias voltage greater than 1.5 V presents a continuous 0°–360° differential phase shift over a frequency range from 0 to 33 GHz. It is demonstrated that the minimum insertion loss is about 0.5 dB and that the return loss is less than-10 dB over the frequency band of 0–33 GHz at a reverse bias voltage less than 4.5 V. These excellent characteristics, such as broad differential phase shift, low insertion loss, and return loss, indicate that the proposed phase shifter can entirely be integrated into a phased array radar circuit.

Study of Liquid Phase Shifter for ICRF on EAST

A method of current drive with Ion Cyclotron Range of Frequency （ICRF） on Experimental Advanced Superconducting Tokomak （EAST） is described. A variety of liquid silicon oil heights in the phase shifter will bring the phase difference to the current drive. It is found that the current drive can be achieved by using the phase shifter. The liquid phase shifter is one of the impedance matching systems too.

Preparation and Microstrutures of BSTO/MgO Ferroelectric Materials for Phase Shift

Barium strontium titanate/magnesia （BSTO/MgO） ferroelectric material for phase shift was prepared by traditional solid phase synthesis. The phase distribution, microstructure and electric properties were investigated. The results show that no secondary phase appears in the composites and the dimension of grains distributes uniformly. With 50 wt% MgO content, the dielectric tunability reaches 17.5 % in the external DC field of 4 000 Vomm^-1 and the microwave loss at about 2.5 GHz is 8×10^-3. Hence, it can be applied in tunable microwave phase shifters.

A 60 GHz Phased Array System Analysis and Its Phase Shifter in a 40 nm CMOS Technology

A 60 GHz phased array system for mm wave frequency in 5G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented.In a phased array system,the signal to noise ratio(SNR)of the receiver is improved with the beaming forming function.Therefore,the communication data rate and distance are improved accordingly.The phase shifter is the key component for achieving the beam forming function,and its resolution and power consumption are also very critical.In the second half of this paper,an analysis of phase shifter is introduced,and a 60 GHz 5 bit digitally controlled phase shifter in 40 nm complementary metal oxide semiconductor(CMOS)technology is presented.In this presented phase shifter,a hybrid structure is implemented for its advantage on lower phase deviation while keeping comparable loss.Meanwhile,this digitally controlled phase shifter is much more compact than other works.For all 32 states,the minimum phase error is 1.5°,and the maximum phase error is 6.8°.The measured insertion loss is-20.9±1 dB including pad loss at 60 GHz and the return loss is more than 10 dB over 57-64 GHz.The total chip size is 0.24 mm^2 with 0 mW DC power consumption.

A new broadband differential phase shifter fabricated using a novel CRLH structure

Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented.

New Feedback Architecture for VCO-Based Delta-Sigma ADCs Utilizing Phase Shifter

The voltage controlled oscillator-based （VCO-based） continuous-time delta-sigma （CTDS） analog to digital converter （ADC） suffers from nonlinearity and mismatch in its feedback network. A new feedback network consisting of a phase shifter is proposed. The phase shifter replaces the digital to analog converter （DAC） in the proposed architecture. Feasibility of the proposed idea is discussed and its higher performance is illustrated through a behavioral simulation approach （CppSim）. We have also developed the phase shifter as a variable all-pass filter in the C language. The nonlinearity and mismatch of the system caused by DAC is mitigated, resulting in higher signal to noise ratio （SNR） and signal to noise and distortion ratio （SNDR）, respectively.

Theory study on a photonic-assisted radio frequency phase shifter with direct current voltage control

A photonic-assisted radio frequency phase shifter with direct current voltage control is proposed using a polymer- based integrated Mach-Zehnder modulator. A closed-form expression of radio frequency （RF） signal power and phase is given. Theoretical calculation reveals that by carefully setting the bias voltages, RF signal power variation lower than 1-dB and phase accuracy less than 3° can be achieved and are not degraded by perturbation of modulation index once the bias voltage drift is kept within -3% -- 3%.

Dispersion suppression scheme for Mach-Zehnder interferometer based interleaver using phase shifter

To suppress the dispersion effect, an improved scheme was proposed for Mach-Zehnder intefferometer （MZI） based interleaver. The device consists of an MZI, a fiber loop （FL）, and a phase shifter inserted in FL. The introduction of π phase shifter into FI, dramatically suppresses the dispersion effiect. Then the transmission response remains square-like shape, with low frequency deviation and high extinction ratio. Moreover, the lower frequency deviation is achieved by reducing the dispersion coefficient. For 100GHz-spacing interleaver, the 0.08nm deviation is reduced to 0.02nm by replacing G.652 with G.655.

Wide-Angle Scanning Antennas for Millimeter-Wave 5G Applications

The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.

Energy‑efcient integrated silicon optical phased array

An optical phased array(OPA)is a promising non-mechanical technique for beam steering in solid-state light detection and ranging systems.The performance of the OPA largely depends on the phase shifter,which afects power consumption,insertion loss,modulation speed,and footprint.However,for a thermo-optic phase shifter,achieving good performance in all aspects is challenging due to trade-ofs among these aspects.In this work,we propose and demonstrate two types of energy-efcient optical phase shifters that overcome these trade-ofs and achieve a well-balanced performance in all aspects.Additionally,the proposed round-spiral phase shifter is robust in fabrication and fully compatible with deep ultraviolet(DUV)processes,making it an ideal building block for large-scale photonic integrated circuits(PICs).Using the high-performance phase shifter,we propose a periodic OPA with low power consumption,whose maximum electric power consumption within the feld of view is only 0.33 W.Moreover,we designed Gaussian power distribution in both the azimuthal(ψ)and polar(θ)directions and experimentally achieved a large sidelobe suppression ratio of 15.1 and 25 dB,respectively.