Monocycle Pulse Research Articles

Pulsed Line Source Response of a Thin Sheet With High-Contrast Dielectric and Conductive Properties—A Time-Domain Analysis

A methodology is presented for analytically modeling the reflection and transmission of line-source excited pulsed electromagnetic fields at a thin, planar layer with high-contrast dielectric and conductive properties. Closed-form analytic time-domain expressions are derived for the field components in a 2-D setting via an extension of the Cagniard-DeHoop method. The response to the power exponential source and the power exponential monocycle pulse were studied using the newly proposed method.

UWB monocycle pulse generation based on colourless silicon photonic integrated circuit

Ultra-wideband monocycle pulse generation is experimentally demonstrated on a silicon photonic circuit with a monolithically integrated wavelength-tunable phase-intensity modulation converter and a waveguide germanium photodetector. A fractional bandwidth of 166% is achieved and modulation with a 2.5 Gbit/s test data pattern was demonstrated.

Generation of UWB pulses using direct modulation of semiconductor laser and optical filtering

A new method to generate ultra-wideband (UWB) pulses based on direct modulation of laser and optical filtering is demonstrated. The intensity modulation and the frequency modulation of the directly modulated laser are combined by the optical filter, which performs a photonic electro-optical derivative operation. Gaussian driving pulses are used in order to generate monocycles for ultra-wideband systems. In association with laser power oscillation, doublet waveforms could also be obtained. Monocycle and doublet pulses are experimentally generated with fractional bandwidths of 139 and 105%, respectively.

A photonic ultra-wideband pulse generator by employing two paralleled Mach–Zehnder modulators

A scheme to generate ultra-wideband (UWB) pulses is presented and demonstrated. The key characteristic is that two paralleled Mach–Zehnder modulators are employed. The two Mach–Zehnder modulators are biased at full point and null point, respectively. By adjusting time delay difference between the output optical pulses at two Mach–Zehnder modulators, the UWB pulses can be generated. Firstly, theoretical analysis of this method is done; then, we verify the approach by simulation with commercial software. The results show that three category UWB pulses can be obtained as follows: Gaussian doublet pulse, negative Gaussian monocycle pulse and positive Gaussian monocycle pulse. The RF spectrum fulfill Federal Communication Commission (FCC) requirement.

A Novel Approach to All-Optical Generation of Ultra-Wideband Signals

The generation of ultra-wideband signals in the optical domain is highly desirable for ultra-wideband-over-fiber systems, which has recently become a topic of interest. In this article, a novel and simple approach to achieve all-optical generation of ultra-wideband signals is proposed, which is based on delaying and superimposing optical Gaussian pulses with opposite polarities. The proposed system is capable of generating both ultra-wideband monocycle and doublet pulses, and the polarity of the generated ultra-wideband monocycle pulses can be fast-switched to implement pulse polarity modulation with the required bit pattern. A model to describe the proposed system is developed, and the generation of ultra-wideband signals is demonstrated with simulations and a proof-of-concept experiment.

A Compact Ferrite-Based Dipole Directional Antenna for Borehole Radar Application

A compact ferrite-based directional antenna has been designed to serve in a directional borehole radar system with a center frequency at 100 MHz and a bandwidth from 70 to 180 MHz. The parameters of the antenna are with a 6:1 power front-to-back ratio and a ±60° directional diagram at half peak amplitude, and the tailing duration of the receiving pulse was about a half pulsewidth while the antenna was placed in the granite borehole and fed by a monocycle pulse with 10-ns duration. The dimensions of the antenna are 48 mm × 54 mm × 440 mm . Experimental results are in good agreement with the simulation results offered by the commercial software (CST MWS) and suggest that the proposed antenna is suitable for the directional borehole radar application.

Reconfigurable photonic ultrawideband pulse generation from an optically injected semiconductor laser

We demonstrate reconfigurable photonic ultrawideband (UWB) pulse generation by injecting a phase-modulated optical wave into a semiconductor laser. By adjusting the injection power level and phase modulation depth, the photonic UWB generator is capable of generating either a single-optical-carrier monocycle or power-efficient UWB pulses. A UWB pulse with spectral power efficiency (SPE) of 36.10% has been achieved by optimizing the injection parameters. Transmission in an 8.4 km single mode fiber results in a degradation of SPE to 27.55% without significant pulse distortion.

Photonic multi-shape UWB pulse generation using a semiconductor optical amplifier-based nonlinear optical loop mirror

We propose and demonstrate a scheme to implement photonic multi-shape ultra-wideband (UWB) signal generation using a semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM). By employing the cross phase modulation (XPM) effect, cross gain modulation (XGM), or both, multi-shape UWB waveforms are generated including monocycle, doublet, triplet, and quadruplet pulses. Both the shapes and polarities of the generated pulses are flexible to adjust, which may be very useful in UWB pulse shape modulation and pulse polarity modulation.

Photonic ultrawideband impulse radio shape modulation based on dual-filter tuning

A simple and flexible photonic scheme for the generation of ultrawideband (UWB) pulse shape modulation based on dual-filter tuning is proposed and experimentally demonstrated. By launching a Gaussian signal into a phase modulator, the UWB polarity-switchable monocycle is generated at the output of two optical bandpass filters by adjusting the central wavelengths of the dual-filter appropriately. The doublet pulses with inverted polarities are obtained by combining the pair of UWB monocycle pulses under proper time delay. Meanwhile, with a predefined code pattern and controlling the optical path difference of the two monocycle pulses, the pulse shape modulation can be performed.

An Improved Ultra-Wideband, Ultra-Short Monocycle Pulse Generator

This paper presents an improved ultra-wideband monocycle pulse generator circuit based on step recovery diode. This pulse generator circuit uses short-circuit microstrip transmission line to generate the Gaussian pulse the monocycle pulse. The improved pulse-shaping network employs two schottky diodes and a MESFET to suppress the pulse ringing. The SRD model was built in RF simulation software ADS, and then the design and simulation of the pulse generator circuit was accomplished using this model. The experiments showed an monocycle pulse of 400ps pulse width with good symmetry. The measured results agreed with the simulation.

A PSO-Based UWB Pulse Waveform Design Method

The pulse waveform design method for ultra wideband (UWB) communication based on particle swarm optimization (PSO) technique is discussed, and the performance of UWB system with designed pulse is analyzed. According to analysis, the design of pulse is transformed into a process of finding the minimal solution of a function about weighting coefficient. The weighting coefficients are made certain based on PSO algorithm. The properties such as bit error rate (BER) performance in both single link and multi-user, link budget of the UWB system employing the designed pulse are simulated. Compared with Scholtz’s monocycle and random combined pulse, the results showed that the pulse designed based on the PSO algorithm has better BER performance and communication performance.

A novel 7 Gbps low-power CMOS ultra-wideband pulse generator

In this study, a novel low-power high data rate ultra-wideband (UWB) pulse generator circuit is presented, which can be fully integrated in complementary metal oxide semiconductor (CMOS) process. The basic part of the circuit generates a UWB Gaussian monocycle pulse using the triangular pulse generation technique. A new bipolar phase shift keying pulse modulator is designed to control the polarity of the output pulses. The design includes additional functionality to make the pulse generator also applicable for transmitted reference (TR) signalling system. The circuit can generate pulses at a maximum rate of 7 giga pulse per second (Gpps) without TR pulse (TRP) and 3.5 Gpps with TRP. The generated pulses are symmetrical, each having a width of 142 ps and a peak-to-peak swing of 500 mV. The −3 dB bandwidth of the pulse spectrum is 9 GHz. The pulse generator consumes only 1.13 pJ per pulse from 1.2 V supply. The circuit is designed and simulated in 90 nm CMOS technology.

Edge-Triggered Ultra-Wideband Pulse Shaper Using Polarization-to-Intensity Conversion

A simple edge-triggered and chirp-free ultra-wideband (UWB) monocycle pulse shaper was proposed and demonstrated utilizing a nonlinearly operated polarization-to-intensity converter, which mainly consists of a polarization modulator (PolM), two polarization controllers (PCs), and a time-delay device. As static phase shift of the incident light φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> =π, a 500-MHz monocycle pulse sequence with 10-dB bandwidth of 10 GHz and fractional bandwidth of 133% was obtained while a 250-MHz electrical quasi-square-wave was applied on the PolM. In addition, polarity switch of the UWB monocycle pulse can be realized by adjusting the bias voltage of the PolM or controlling the PC.

Photonic ultrawideband impulse radio generation and modulation over a fiber link using a phase modulator and a delay interferometer

We propose and experimentally demonstrate a simple and flexible photonic scheme for generation and modulation of ultrawideband (UWB) using a phase modulator and a fiber delay interferometer (DI)-based multichannel frequency discrimination. By introducing a Gaussian signal to the phase modulator, the UWB polarity-switchable doublet pulses can be achieved by combining the pair of UWB monocycle pulses with inverted polarities at the DI outputs under proper time delay. Furthermore, the pulse shape modulation, pulse position modulation, and on-off keying can be performed by coding the electrical data patterns and adjusting the time delay between the two monocycle pulses. Only a laser source introduced in the architecture guarantees the excellent dispersion tolerance over 75 km optical fiber link for UWB pulse sequence, which has potential application in future high-speed UWB impulse radio over optical fiber access networks.

Intense Terahertz Pulse-Induced Nonlinear Responses in Carbon Nanotubes

By using intense terahertz(THz) monocycle pulses, nonlinear light-matter interaction in aligned semiconducting single-walled carbon nanotubes(SWNTs) embedded in a polymer film was investigated. THz electric-field-induced ultrafast Stark effect of one-dimensional excitons in SWNTs was observed at room temperature, suggesting the potential functionality of SWNTs for high speed electro-optic devices operating at telecom wavelength with a THz bandwidth. When the peak electric field amplitude exceeds 200 kV/cm, the generation of excitons by the THz pump becomes prominent. The mechanism is described by the above-gap excitation of electrons and holes in SWNTs due to the impact excitation process induced by the intense THz electric field.

Gigabit/s Photonic Generation, Modulation, and Transmission for a Reconfigurable Impulse Radio UWB Over Fiber System

We propose and demonstrate a flexible and high-speed impulse radio ultrawideband (IR-UWB) over fiber system using various modulation schemes. Two kinds of fully Federal Communication Commission (FCC) compliant UWB pulses are produced, which is based on the incoherent summation of multiple monocycle pulses with inverse polarities, proper time delays, and different weights. Theoretically, their spectral power efficiency can achieve 33.9% and 47.4%, respectively, which is much higher than that of the conventional monocycle and doublet pulses. A good agreement between the theoretical and experimental results for the generation of designed UWB pulses is also observed. Moreover, electrically reconfigurable multiple modulation formats such as on-off keying (OOK) modulation, binary phase shift keying (BPSK) modulation, pulse shape modulation (PSM), and pulse position modulation (PPM) are implemented experimentally. Furthermore, the UWB signals with OOK, BPSK, and PPM are transmitted over a combined wired (single-mode fiber) and wireless link. The transmission performance of the newly generated UWB pulses is then evaluated by electrical spectra, eye diagrams, and bit-error-rate measurements. For all the modulation formats, a forward-error-correction (FEC)-limit error-free operation is obtained, and the power penalties of transmission are less than 1 dB.

Repulsion-to-attraction transition in correlated electron systems triggered by a monocycle pulse

We study the time evolution of the Hubbard model driven by a half-cycle or monocycle pulsed electric field F(t) using the nonequilibrium dynamical mean-field theory. We find that for properly chosen pulse shapes the electron-electron interaction can be effectively and permanently switched from repulsive to attractive if there is no energy dissipation. The physics behind the interaction conversion is a nonadiabatic shift $\delta$ of the population in momentum space. When $\delta\sim\pi$, the shifted population relaxes to a negative-temperature state, which leads to the interaction switching. Due to electron correlation effects $\delta$ deviates from the dynamical phase $\phi=\int dt F(t)$, which enables the seemingly counterintuitive repulsion-to-attraction transition by a monocycle pulse with $\phi=0$.

UWB Monocycle Generation and Bi-Phase Modulation Based on Mach–Zehnder Modulator and Semiconductor Optical Amplifier

We propose and experimentally demonstrate an approach in generating a pair of polarity-reversed ultra-wideband (UWB) monocycle pulses by using a Mach-Zehnder modulator (MZM) and a semiconductor optical amplifier (SOA). The monocycle polarity is controlled by adjusting the bias voltage of the MZM to make the bias point located at the positive or the negative slope of the modulation curve. The generated UWB monocycles with different injection currents of SOA, different bias voltages of MZM, different optical pulse widths, and different optical carrier wavelengths are experimentally studied and analyzed. The bi-phase modulation (BPM) of monocycle pulse by applying nonreturn-to-zero (NRZ) data to the radio frequency (RF) port of MZM is also proposed and investigated.

Photonic generation of power-efficient FCC-compliant ultra-wideband waveforms using semiconductor optical amplifier (SOA): theoretical analysis and experiment verification

We theoretically design a power-efficient ultra-wideband pulse generator by combining three monocycle pulses with different weights. We also experimentally demonstrate a feasible scheme to generate such power-efficient ultra-wideband waveforms using cross-phase modulation in a single semiconductor optical amplifier. The designed ultra-wideband pulse fully satisfies the requirements for the spectral mask specified by the Federal Communications Commission with high power efficiency. In the experiment, a power-efficient ultra-wideband waveform with a pulse duration of 310 ps is achieved, and the power efficiency is greatly improved compared with that of a single monocycle pulse or a mixture of two monocycles.

Bismuth Nonlinear Optical Fiber for Photonic Ultrawideband Radio-Signal Processing

The feasibility of using a bismuth-oxide-based nonlinear optical fiber (Bi-NLF) for the implementation of ultrawideband (UWB) radio-signal-processing schemes is experimentally investigated. The use of two different types of nonlinear signal processors for the generation of UWB pulses is demonstrated. One processor uses cross-phase modulation for monocycle pulse generation, whereas the other uses nonlinear polarization rotation for doublet pulse generation. It is experimentally shown that UWB monocycle and doublet pulses can be successfully generated using the Bi-NLF-based nonlinear signal processors. Moreover, the system performance for the generation of UWB pulses is evaluated by performing a transmission experiment over a 20-km-long nonzero dispersion-shifted fiber (NZ-DSF) link. Error-free and penalty-free UWB doublet signal transmission is achieved.