Ultra-wideband Monocycle Research Articles

Optical generation of UWB pulses utilizing Fano resonance modulation.

In this paper, we reported an integrated method to generate ultra-wideband (UWB) pulses of different orders based on a reconfigurable silicon micro-ring resonator-coupled Mach-Zehnder interferometer. Under proper operating conditions, the device can produce Fano resonances with a peak-to-valley extinction ratio of above 20 dB. UWB monocycle and doublet signals with picosecond pulse widths are produced when the microring resonator is modulated by square and Gaussian electrical pulses, respectively. With our Fano resonance modulator on silicon photonics, it is promising to foresee versatile on-chip microwave signal generation.

Ultra-wideband doublet signal generation with tunable notch band based on delay-line filter

ABSTRACT A novel and simple scheme to generate Ultra-wideband (UWB) doublet signal with tunable notch band based on a tunable delay-line filter is presented. The first-order differentiation is realized by a dual-drive Mach–Zehnder modulator (DD-MZM), which differentiates the Gaussian pulses to the monocycle pulses. Subsequently, the UWB monocycle pulses are transmitted to an optical delay-line filter implemented by a balanced photo-detector and a tunable delay line for both differentiation and photodetection. Consequently, the desired UWB doublet signal can be obtained with a 10-dB bandwidth of 8.75 GHz. Besides, the polarity reversibility of the generated doublet signal is demonstrated by changing the bias voltage of the DD-MZM. Moreover, the desired notch can be introduced in the generated frequency spectrum to eliminate the interference between the existing narrowband systems and the UWB systems. And the tunability of the band-notched position is implemented by simply adjusting the delay time of the delay-line filter. The feasibility of the presented scheme is investigated by mathematical models and simulations.

Photonic generation of MMW-UWB monocycle and doublet signals based on frequency up-conversion and delay-line filter

A photonic approach to generate millimeter-wave (MMW) ultra-wideband (UWB) monocycle and doublet signals using stimulated Brillouin scattering (SBS) selective sideband amplification technique and delay-line filter is proposed and theoretically analyzed. In the proposed approach, a dual-drive Mach–Zehnder modulator (DDMZM) is used as a first-order differentiator to produce a monocycle UWB signal. Then the generated monocycle signal is single-sideband (SSB) modulated by SBS effect for up-conversion. A balanced photodetector (BPD) is further employed for both photodetection and first-order differentiation. Consequently, an MMW-UWB monocycle signal or an MMW-UWB doublet signal can be attained in electrical field with controlling an optical switch. The frequency spectra of the generated MMW-UWB monocycle and doublet signals meet well with the Federal Communication Committee (FCC) mask with power efficiency of 50.63% and 40.53%. Besides, the produced MMW-UWB signals can be employed to realize multiple modulation formats, such as on–off keying modulation (OOK), pulse position modulation (PPM) and pulse amplitude modulation (PAM).

Photonic generation of millimeter-wave ultra-wideband monocycle signal using up-conversion based on stimulated Brillouin scattering effect

We propose a novel scheme for photonic generation of millimeter-wave (MMW) ultra-wideband monocycle signal free of strong local oscillation (LO) and low-frequency component. A theory and a mathematical model are built to investigate the proposed scheme. Firstly, a differentiator is implemented using a dual-drive Mach–Zehnder modulator to attain monocycle pulses by differentiating a series of Gauss pulses. Subsequently, a dual-parallel Mach–Zehnder modulator and stimulated Brillouin scattering effect are employed to realize single-sideband modulation for up-converting the monocycle pulses to the MMW band. In the calculation, the generated signal is centered at 26 GHz with 10-dB bandwidth of 7 GHz and its power efficiency is about 50.08%. In addition, on–off keying modulation, amplitude modulation (PAM) and pulse position modulation monocycle pulses are generated. The spectrum of the generated signal meets with the FCC mask efficiently, so this technique has a potential application in MMW radar communication systems.

Proposal for all-optical switchable and tunable ultrawideband monocycle generation utilizing SOA wavelength conversion and time delay

An all-optical ultrawideband monocycle generator based on wavelength conversion in a semiconductor optical amplifier (SOA) and optical tunable delay in an optical delay line (ODL) is proposed and simulated. The system achieves optically switchable in pulse polarity and tunable in both the pulsewidth and radio frequency (RF) spectrum.

Photonic UWB pulse generation and OOK, PPM, BPSK modulation for WDM systems based on twin-core fiber

We propose and demonstrate an approach for optical ultra-wideband (UWB) monocycle pulses generation by employing a phase modulator (PM) and twin-core fiber (TCF). Based on phase modulation to intensity modulation (PM-IM) conversion principle, multi-wavelength and polarity-reversed ultra-wideband (UWB) monocycle pulses are generated simply by making the optical carrier wavelength located at the positive or negative sloop of the periodic comb-transmission spectrum of TCF. The generated UWB monocycles with different optical carrier wavelengths are studied and analyzed. In addition, multiple modulation formats such as on-off keying (OOK), pulse position modulation (PPM) and binary phase shift keying (BPSK) are implemented. Simulation results show that the proposed scheme can offer a realistic solution to photonic UWB pulse generation and modulation for WDM systems.

Ultra-wideband signal generator based on cross gain modulation effect in a distributed feedback laser

In this paper, a novel scheme to generate ultra-wideband (UWB) signals based on cross-gain modulation (XGM) effect in a DFB laser is proposed and experimentally demonstrated, and the modulation and transmission of the UWB signals are also experimentally investigated. In the proposed system, a gain-switched laser (GSL) is used as master laser (ML) and the optical pulses from the ML are optically injected into a DFB laser, which is used as slave laser (SL). By proper system configuration, UWB monocycle, doublet or triplet UWB signals can be generated after the balanced photodiode (BPD) detection. Besides, other modulation formats can also be realized, such as on-off keying (OOK) and pulse amplitude modulation (PAM) by properly modulating the ML optical pulses. Finally, fiber transmission of the modulated UWB signals is experimentally investigated, and it is shown that the UWB signals can be well maintained after 40km optical fiber transmission.

Photonic generation of filter-free ultrawideband monocycle and doublet signal using single semiconductor optical amplifier in counter-propagation scheme

We propose and demonstrate a flexible and filter-free method to generate ultrawideband monocycle and doublet pulses utilizing cross-gain modulation in a semiconductor optical amplifier. The counter-propagation scheme and UWB-over-fiber technology is implemented by exploiting dispersion-induced pulse broadening effect in a single-mode fiber. Owing to the counter-propagation scheme, the pump and probe light can be the same wavelength, which could provide the system better dispersion performance.

Amplitude and Phase Modulation of UWB Monocycle Pulses on a Silicon Photonic Chip

We demonstrate both the amplitude and bi-phase modulation of ultrawideband (UWB) monocycle pulses using silicon microring modulator. The integrated silicon ring modulator generates the monocycle pulse train and modulates it simultaneously. By applying different driving voltages, the amplitude and phase-modulated UWB signal with a data rate of 2.5 Gb/s are achieved. The ring modulator can be thermally tuned for a free spectral range with a $\sim 50$ -mW power consumption.

A Novel Low-Ringing Monocycle Picosecond Pulse Generator Based on Step Recovery Diode.

This paper presents a high-performance low-ringing ultra-wideband monocycle picosecond pulse generator, formed using a step recovery diode (SRD), simulated in ADS software and generated through experimentation. The pulse generator comprises three parts, a step recovery diode, a field-effect transistor and a Schottky diode, used to eliminate the positive and negative ringing of pulse. Simulated results validate the design. Measured results indicate an output waveform of 1.88 peak-to-peak amplitude and 307ps pulse duration with a minimal ringing of -22.5 dB, providing good symmetry and low level of ringing. A high degree of coordination between the simulated and measured results is achieved.

Ultrawideband monocycle pulse generation based on polarization modulator and low speed electrical NRZ signal

A novel ultrawideband (UWB) monocycle pulse generation system by modulating a polarization modulator (PolM) with a low speed electrical nonreturn-to-zero (NRZ) signal is proposed, which significantly reduce the bandwidth requirement of the driving signal. At each bit transition of the input NRZ signal, two polarity-reversed Gaussian pulses are generated. By properly setting the delay between these two Gaussian pulses, an optical UWB monocycle pulse can be generated. Biphase modulation (BPM) can be realized by electrically switching the polarization direction at the output of PolM, if an electrically tunable arbitrary wave plate (AWP) is employed.

Ultra Wideband Monocycle pulse generation using SRD and Coupled line band pass filter with reduced ringing level

Ultra Wideband Monocycle pulse generation using SRD and Coupled line band pass filter with reduced ringing level

Polarity-reversed ultra-wideband monocycle pulse generation with dual-channel multicasting in a photonic crystal fiber

This paper proposes and demonstrates a novel scheme of a two-channel-output ultra-wideband monocycle pulse generator consisting of a 100 m dispersion-flattened highly nonlinear photonic crystal fiber and two optical bandpass filters. Based on the cross-phase modulation effect in a dispersion-flattened highly nonlinear photonic crystal fiber, two polarity-reversed ultra-wideband monocycle pulses simultaneously output from two different channels are successfully achieved by appropriately locating the probe wavelength at the left linear slope and the right linear slope of the two optical bandpass filters transmission spectra, respectively. The full width at half-maximum and a fractional bandwidth of 24 ps and 260% for a positive pulse, 24 ps and 251% for a negative pulse are obtained. Moreover, the influences of input signal powers, the polarization misalignment between the data light and the continuous wave probe light, and probe wavelength variation on the double output ultra-wideband signals quality are also investigated. The results show that the system has some tolerance to both the input signal power fluctuation and the slight polarization mismatch and even can efficiently operate with a widely tunable wavelength range. This makes it very attractive for engineering applications in future multiuser ultra-wideband-over-fiber communication systems.

Reconfigurable UWB Pulse Generation Based on a Dual-Drive Mach–Zehnder Modulator

We propose and experimentally demonstrate a reconfigurable ultrawideband (UWB) pulse generation scheme by using a dual-drive Mach-Zehnder modulator (DDMZM). In the proposed method, two phase modulators of the DDMZM are respectively driven by properly designed electrical signals. By carefully setting the parameters of the two electrical signals and the bias voltage of the DDMZM, different UWB pulses can be achieved at the interference output of the DDMZM. A proof-of-concept experiment verifies the feasibility of the proposed method. Photonic generations of UWB monocycle, doublet, triplet, and quintuple pulses have been successfully demonstrated, with central frequencies of 4.69, 4.69, 5.47, and 6.25 GHz and fractional bandwidths of 150%, 133%, 186%, and 75%, respectively.

UWB Monocycle Generator Based on the Non-Linear Effects of an SOA-Integrated Structure

In this letter, we propose and experimentally demonstrate a novel and single structure to generate ultra-wideband (UWB) pulses by means of the cross-phase modulation present in a semiconductor optical amplifier unified structure. The key components of this system is an integrated Mach-Zehnder interferometer with two semiconductor optical amplifiers and an optical processing unit. The fusion of these two components permits the generation and customization of UWB monocycle pulses. The polarity of the output pulses is easily modified through the single selection of a specific input port. Moreover, the capacity of transmitting several data sequences is demonstrated and the potentiality to adapt the system to different modulation formats is analyzed.

A UWB pulse generation based on a phase modulator and programmable filter

A simple scheme for the ultra-wideband (UWB) pulse generation based on a phase modulator and programmable filter is proposed and experimentally demonstrated. By locating the center wavelength of two tunable lasers at left and right linear slope of the filter, polarity-reversed monocycle pluses are generated. A section of single mode fiber is utilized to introduce proper time delay between the pair of UWB monocycle pulses. By switching the programmable filter between bandpass filter and notch filter, positive and negative doublet pulse can be obtained additionally. The generated UWB pulses are measured in both time and frequency domain.

A Novel Subnanosecond Monocycle Pulse Generator for UWB Radar Applications

A novel ultra-wideband (UWB) monocycle pulse generator with good performance is designed and demonstrated in this paper. It contains a power supply circuit, a pulse drive circuit, a unique pulse forming circuit, and a novel monopolar-to-monocycle pulse transition circuit. The drive circuit employs wideband bipolar junction transistors (BJTs) and linear power amplifier transistor to produce a high amplitude drive pulse, and the pulse forming circuit uses the transition characteristics of step recovery diode (SRD) effectively to produce a negative narrow pulse. At last, the monocycle pulse forming circuit utilizes a novel inductanceLshort-circuited stub to generate the monocycle pulse directly. Measurement results show that the waveform of the generated monocycle pulses is over 76 V in peak-to-peak amplitude and 3.2 ns in pulse full-width. These characteristics of the monocycle pulse are advantageous for obtaining long detection range and high resolution, when it is applied to ultra-wideband radar applications.

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.

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.

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.