In this paper, we first investigate the power spectral densities (PSD) of bipolar modulated Direct Sequence Ultra Wide Band (DS-UWB) signals using various pulse shapes under the FCC UWB emission mask. Considered pulse shapes are the first five derivatives of the Gauss pulse (p1, p2, p3, p4 and p5), the first four orthogonal modified Hermite waveforms, and Daubechies wavelets (db-q). It is obser...

With their short nanosecond pulse durations, Qswitched lasers have revolutionized the treatment of tattoos [1-3]. Nevertheless, the mechanisms for clinically observed tattoo clearance are still not well understood. Two mechanisms have been proposed: a) a thermal effect where tattoo particles are heated to sufficiently high temperatures to cause chemical changes within the particles and the surr...

LED PWM dimming application for large scale LED video displays is analyzed. The need for short light pulse duration is outlined. PWM dimming with short driving pulses is investigated experimentally. The LED response time skew introduces the nonlinearity for PWM dimming. For LED response time skew estimation, a method is suggested that has been successfully applied to measure some of today’s mar...

We theoretically and experimentally studied the dispersion effects in an actively mode-locked inhomogeneously broadened laser. In the positive group velocity dispersion (GVD) region, the laser generates incoherent pulses. Self-phase modulation and resonant dispersion impede reduction of the pulse duration when the GVD is small or near zero. A single, stable, soliton-like pulse can be generated ...

Electrical discharge machining (EDM) is highly utilized in manufacturing sectors owing to its ability to machine high strength materials with complex shape. The pulse duration of the pulse generator highly determines the machinability in such process. Since the duty factor can characterize the pulse duration, it is very essential to analyze its effect on machinability in the process. In the pre...

We analyze the time profiles of individual gamma-ray burst (GRB) pulses, that are longer than 2 s, by modelling them with analytical functions that are based on physical first principles and well-established empirical descriptions of GRB spectral evolution. These analytical profiles are independent of the emission mechanism and can be used to model both the rise and decay profiles allowing for ...

Ultra-short laser pulses with femtosecond to attosecond pulse duration are the shortest systematic events humans can create. Characterization (amplitude and phase) of these pulses is a key ingredient in ultrafast science, e.g., exploring chemical reactions and electronic phase transitions. Here, we propose and demonstrate, numerically and experimentally, the first deep neural network technique ...

The thermoelectric response of amorphous, semiconducting Y–Ba–Cu–O thin films was investigated by illumination with 150 ps optical pulses at 1064 nm and with a continuous wave at 493 nm ~argon laser!. The measured unbiased voltage response was consistent with pyroelectricity. At high pulse energies, the voltage response saturated due to the saturation of the spontaneous polarization. The pulsed...

The goal of this paper is to explore the power of genetic algorithms, in particular the so called micro genetic algorithms, to solve a challenging problem in experimental physics. The problem is to find an optimum frequency to stabilize atoms by high-intensity laser fields. The standard approach to search for optimal laser parameters has been by trial and error. This is the first known applicat...

From classical charge transport equations and dipole radiation equations, we derive a simple analytical model for the signal detected in terahertz time-domain spectroscopy using photoconducting antennas. The validity of our model is checked by comparison to published calculated results and to experimental data we have measured. This expression depends mostly on the carrier lifetime in the anten...