Ultra-wideband Pulse Generator Research Articles

Research of all-optical ultra-wideband triplet signal source based on a single semiconductor optical amplifier

A novel scheme for all-optical ultra-wideband triplet signal pulse generation based on the cross-gain modulation (XGM) in a single semiconductor optical amplifier (SOA) is demonstrated. In this scheme, only one optical source and one SOA are needed, so the configuration is simple. Due to only one wavelength is included in the generated triplet pulse, no time difference between output signal light and probe light is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the input signal width, the optical power and the wavelength of the optical source on the generated triplet pulse are numerically simulated and studied. The results show that the proposed scheme has better triplet signal pulse when the input signal pulse width is larger, and it is insensitive to the wavelength change within a certain range.

Adaptive narrowband interference mitigation by designing UWB waveforms based on radial basis function neural networks

In order to mitigate the mutual interference between ultra-wideband (UWB) impulse radio and other existing wireless systems, a novel adaptive interference-avoiding UWB pulse, in the context of the appealing cognitive radio, is presented based on the radial basis function neural networks. Theoretical and implementation architecture for UWB pulse generator is addressed. Transmission performance in the presence of narrowband interference including tone interference is comprehensively analyzed. The presented generator can adaptively change the spectrum shape of UWB signals according to the authorized users’ working states, and hence the mutual interference between UWB and other systems sharing the frequency bands can efficiently be avoided. The critical performance indication parameters, such as the SNR, SIR, and BER of UWB communication links, are also derived. Performance evaluations and comparisons between the proposed scheme and other pulse optimization methods have been provided based on the extensive numerical simulations. It is demonstrated that the presented pulse can indeed achieve much superior performance in terms of either single-link BER or anti-jamming capability.

Generation and radiation of high-power ultrawideband pulses with controlled spectrum

A pulsed source of the ultrawideband radiation based on a nonlinear line and a single combined antenna is proposed. The frequency that corresponds to the maximum radiation spectrum can be tuned in the interval 0.5–1.3 GHz. The effective radiation potential of the source is 95–310 kV.

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.

Compact, flexible and versatile photonic differentiator using silicon Mach-Zehnder interferometers

We propose and experimentally demonstrate the flexibility and versatility of photonic differentiators using a silicon-based Mach-Zehnder Interferometer (MZI) structure. Two differentiation schemes are investigated. In the first scheme, we demonstrate high-order photonic field differentiators using on-chip cascaded MZIs, including first-, second-, and third-order differentiators. For single Gaussian optical pulse injection, the average deviations of all differentiators are less than 6.5%. In the second scheme, we demonstrate multifunctional differentiators, including intensity differentiator and field differentiator, using an on-chip single MZI structure. These different differentiator forms rely on the relative shift between the probe wavelength and the MZI resonant notch. Our schemes show the advantages of compact footprint, flexible functions and versatile differentiation forms. For example, high order field differentiators can be used to generate complex temporal waveforms, such as high order Hermite-Gaussian waveforms. And intensity differentiators are useful for ultra-wideband pulse generation.

Reconfigurable UWB pulse generator based on pulse shaping in a nonlinear optical loop mirror and differential detection

A reconfigurable impulse radio ultra-wideband (UWB) pulse generator for various UWB shapes (e.g., monocycle, doublet, and triplet pulses) based on a nonlinear optical loop mirror (NOLM) and differential detection is proposed and experimentally demonstrated. The proposed approach can be used with different modulation formats and may be suitable for implementation in future low-cost, high-speed, short-range UWB wireless access applications.

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-chip-based all-optical ultra-wideband pulse generation via XPM and birefringence in a chalcogenide waveguide

We report a photonic-chip-based scheme for all-optical ultra-wideband (UWB) pulse generation using a novel all-optical differentiator that exploits cross-phase modulation and birefringence in an As₂S₃ chalcogenide rib waveguide. Polarity-switchable UWB monocycles and doublets were simultaneously obtained with single optical carrier operation. Moreover, transmission over 40-km fiber of the generated UWB doublets is demonstrated with good dispersion tolerance. These results indicate that the proposed approach has potential applications in multi-shape, multi-modulation and long-distance UWB-over-fiber communication systems.

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.

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.

Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion

We propose and demonstrate a novel scheme to generate ultra-wideband (UWB) triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion. First a phase-modulated Gaussian doublet pulse is generated by four-wave mixing in a highly nonlinear fiber. Then an UWB triplet pulse is generated by generating the first-order derivative of the phase-modulated Gaussian doublet pulse using an optical filter serving as a frequency discriminator. By locating the optical signal at the linear slope of the optical filter, the phase modulated Gaussian doublet pulse is converted to an intensity-modulated UWB triplet pulse which well satisfies the Federal Communications Commission spectral mask requirements, even in the extremely power-restricted global positioning system band.

Optical UWB Waveform Generation Using a Micro-Ring Resonator

Optical generation and transport of ultra-wideband (UWB) pulses extends the reach of these weak signals to several kilometers by exploiting passive optical networks. At the remote node, the UWB transmitter should be low cost and compact in size for indoor communications. We propose and experimentally demonstrate an integrated solution based on a racetrack micro-ring resonator in silicon-on-insulator technology. The resonator filters pulses generated by a gain-switched laser. Frequency-to-time mapping is obtained from fiber propagation. Balanced detection of the pulses ensures FCC-compliant UWB pulse generation.

130 nm CMOS 공정을 이용한 UWB High-Band용 저전력 디지털 펄스 발생기

본 논문에서는 UWB의 6~10 GHz 주파수 대역을 위한 디지털 방식의 CMOS UWB 펄스 발생기를 제안하였다. 제안된 펄스 발생기는 매우 적은 전력 소모와 간단한 구조로 설계 및 구현되었다. 이 펄스 발생기는 가변되는 shunt capacitor 방식으로 구성된 CMOS delay line을 사용하여 중심 주파수를 제어할 수 있게 하였고, Gaussian Pulse Shaping 회로를 이용하여 FCC 등에서 제시하는 UWB 스펙트럼 규정을 만족할 수 있도록 설계하였다. 측정결과, 가변 가능한 중심 주파수는 4.5~7.5 GHz까지 자유롭게 조절이 가능하였고, 펄스의 폭은 대략 1.5 ns였다. 그리고 10 MHz의 PRF 조건에서 310 mV pp의 크기의 펄스 신호를 보여주었다. 회로는 0.13 um CMOS 공정으로 제작되었고, 코어의 크기는 <TEX>$182{\times}65um^2$</TEX>로 매우 작은 크기로 설계되었으며, 평균 소모 전력은 1.5 V 전원을 사용하는 출력 buffer에서 11.4 mW를 소모하고, 이를 제외한 코어에서는 0.26 mW의 매우 작은 전력을 소모하고 있다. In this paper, an all-digital CMOS ultra-wideband(UWB) pulse generator for high band(6~10 GHz) frequency range is presented. The pulse generator is designed and implemented with extremely low power and low complexity. It is designed to meet the FCC spectral mask requirement by using Gaussian pulse shaping circuit and control the center frequency by using CMOS delay line with shunt capacitor. Measurement results show that the center frequency can be controlled from 4.5 GHz to 7.5 GHz and pulse width is 1.5 ns and pulse amplitude is 310 mV peak to peak at 10 MHz pulse repetition frequency(PRF). The circuit is implemented in 0.13 um CMOS process with a core area of only <TEX>$182{\times}65um^2$</TEX> and dissipates the average power of 11.4 mW at an output buffer with 1.5-V supply voltage. However, the core consumes only 0.26 mW except for output buffer.

Photonic generation of UWB pulses with multiple modulation formats

A new photonic approach to generate ultra-wideband (UWB) signals with on–off keying, pulse position and shape modulation is proposed and proved by simulation. The proposed system consists of two parallel similar subsystems, which are both made up of an intensity modulator (IM) and a dual-drive Mach–Zehnder modulator (DD-MZM). The optical signal is injected into the two subsystems with equal intensity and phase. The IMs are driven by the data signal, while the DD-MZMs are driven by the Gaussian pulse train. By properly adjusting the bias points of the IMs and DD-MZMs, the amplitudes of the data signals, and the time delays introduced by electrical delay lines, a position-modulated UWB monocycle, a shape-modulated UWB monocycle and doublet, and an on–off keying UWB monocycle can be generated. The fractional bandwidth of the generated UWB monocycle and UWB doublet are 171% and 150%, respectively.

Photonic generation of ultra-wideband doublet pulse using a semiconductor-optical-amplifier based polarization-diversified loop

We propose and demonstrate a novel scheme of ultra-wideband (UWB) doublet pulse generation using a semiconductor optical amplifier (SOA) based polarization-diversified loop (PDL) without any assistant light. In our scheme, the incoming gaussian pulse is split into two parts by the PDL, and each of them is intensity modulated by the other due to cross-gain modulation (XGM) in the SOA. Then, both parts are recombined with incoherent summation to form a UWB doublet pulse. Bi-polar UWB doublet pulse generation is demonstrated using an inverted gaussian pulse injection. Moreover, pulse amplitude modulation of UWB doublet is also experimentally demonstrated. Our scheme shows some advantages, such as simple implementation without assistant light and single optical carrier operation with good fiber dispersion tolerance.

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.

Filter-free ultra-wideband doublet pulses generation based on wavelength conversion and fiber dispersion effect

Filter-free ultra-wideband (UWB) doublet pulse generation is experimentally demonstrated in the optical domain based on cross-gain modulation (XGM) in semiconductor optical amplifier (SOA) and UWB-over-fiber technology is implemented by exploiting dispersion-induced pulse broadening effect in single-mode fiber (SMF). In our proposed system, the SOA generates a polarity-inversed Gaussian pulse train with respect to the injected one through the XGM. After a piece of SMF, the bandwidth of polarity-reversed Gaussian pulse broadens due to the induced dispersion. After the combination of the two light waves with a suitable time delay between them, UWB pulse is obtained. The key parameters for UWB pulse, including central frequency, 10dB bandwidth, as well as fractional bandwidth are experimentally obtained with 8GHz, 9.9GHz and 123% respectively. The generated UWB doublet pulse conforms with the UWB definition of Federal Communications Commission (FCC).

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.

Coplanar waveguide wideband bandpass filter and its application to ultra-wideband pulse generation

A technique to design wideband coplanar waveguide bandpass filters is reported. The filter is realized by etching a slot on the ground plane around a gap on its central conductor and modifying the gap in the form of parallel lines. It is shown that the 3-dB fractional bandwidth of the filter can be varied from 60 to 110% by tuning the size of the slot aperture and the length of the parallel lines. Equivalent circuit and design steps are presented. Implementation area of the filter having passband 3.2–10.5 GHz is 0.90 λg × 0.26 λg, λg being the guided wavelength at 6.85 GHz while 20-dB stopband is at least up to 18 GHz. Insertion loss is less than 2 dB up to 9 GHz. Area of the filter having fractional bandwidth 60% at 3.85 GHz is 0.67 λg × 0.11 λg. Passband loss is within 1.5 and 20 dB stopband is at least up to 12 GHz. The proposed filter structure is very simple to integrate, and the ultra-wideband filter is used to generate an ultra-wideband pulse as defined by the US Federal Communication Commission. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.

UWB monocycle pulse generation using two-photon absorption in a silicon waveguide

We propose and experimentally demonstrate ultrawideband monocycle pulse generation using nondegenerate two-photon absorption in a silicon waveguide. The free-carrier absorption induced pulse tail at the rising edge of inverted probe pulse is largely compensated by the overlapped pump pulse and results in a symmetric negative monocycle pulse. A 143 ps Gaussian monocycle pulse is successfully obtained with a 131.7% fractional 10 dB bandwidth using a 68 ps pulsed pump. The 10 dB bandwidth and center frequency of the RF spectrum for the generated monocycle pulse can be largely tuned using an optical delay line. An operational bandwidth of 30 nm is demonstrated experimentally with stable performance, and larger optical bandwidth is expected.