We report programmable shaping of femtosecond optical pulses by use of a multielement liquid-crystal modulator to manipulate the phases of spatially dispersed optical frequency components. Our approach provides for continuously variable control of the optical phase and permits the pulse shape to be reconfigured on a millisecond time scale. We use the apparatus to demonstrate femtosecond pulse-p...

The phase noise of a 20 GHz picosecond optical pulse train generated by a modulator-based optical frequency comb generator is analysed. The residual timing jitter is 10 fs for Fourier frequencies from 10 Hz to 10 MHz. Photodetection of the optical pulse train provides millimetre-wave signals with similarly low residual jitter at 40, 60, and 80 GHz with applicable powers of 27.5, 210.5, and 213 ...

Composite rightand left-handed (CRLH) transmission lines with regularly spaced Schottky varactors are characterized for propagation of short envelope pulses. Due to strong dispersion, a short pulse cannot travel on a conventional CRLH line without distortion. This distortion is compensated for by the effects of Schottky varactors such that the line supports solitonic pulses, whose pulse width d...

This paper considers practically relevant aspects and advantages of pulse-shaping orthogonal/biorthogonal frequency division multiplexing (OFDM/BFDM) systems. We analyze the intersymbol/intercarrier interference (ISI/ICI) in such systems when they operate over time-varying channels. Two methods for an ISI/ICI-minimizing pulse design are proposed, and efficient FFT-based modulator and demodulato...

The determination of the frequency spectrum of a pulse width modulated (PWM) signal with general band-limited input x(t) has been an open problem for many years. We describe a new approach that gives exact analytical expressions for the spectra of uniform-sampling PWM signals and natural-sampling PWM signals with single-edge as well as with doubleedge modulation. For the special case of single ...

A system consisting of an unstable linear plant and of a pulse-frequency modulator, as a controller, is considered. Algebraic inequalities, which guarantee the boundedness of all the solutions, are obtained. Copyright c © 2001 IFAC

In order to achieve the transformation of electrical energy in Variable Speed Constant Frequency (VSCF) Wind Power Generation System (WPGS), a novel Space Vector Pulse Width Modulation (SVPWM) pulse trigger technology applied in high efficient PWM rectifier is proposed. Rectifier is an important part of WPGS and its performance affects the harmonic content and power factor of the power energy d...

A RF directional modulation technique using a switched antenna array is proposed for communication and direction-finding applications. The main idea is that a baseband modulation signal is transmitted by the switched antenna array. The phase center of the transmit signal is moved by the feeding line of each element from the left to the right. In this way, the data information and Doppler freque...

We report a two-stage 2-μm Tm3+ fiber amplifier seeded by an acousto-optic modulator (AOM) modulated narrowbandwidth pulsed laser. Maximum output average power is over 50 W (slope efficiency of ∼58%) at 50 kHz repetition rate, providing record performance in nanosecond 2-μm all-fiber-based amplifiers. The maximum pulse energy and peak power are ∼1.0 mJ and 10 kW, respectively. The pulse width c...