Journal of Lasers, Optics & Photonics

A scheme to generate optical arbitrary waveform based on a Dual Parallel Mach-Zehnder modulator (DPMZM) and an optical filter is proposed. One of the child MZMs (MZM-1) of the DPMZM is driven by the Ratio Frequency (RF) and DC bias voltage (Vbias-1), at the same time, the other child MZM (MZM-2) is driven by the RF multiplier and the DC bias voltage (Vbias-2). By adjusting the size of the RF driving voltages and the DC bias voltages, we can get a stable optical frequency comb with high side-comb suppression ratio (SCSR). Then optical frequency comb (OFC) matches with the tunable optical filter by adjusting the spectral line position and spacing, the waveforms of Gaussian, Trapezoid, square wave, sine, half-wave cosine and sinc-shaped pulse with a tunable repetition rate are generated.

In this study, we shall report the spectroscopic studies of the laser induced-Mg plasma in the atmospheric air by a Q-switched Nd-YAG laser operating at its fundamental wavelength of 1062 nm. The plasma was evaluated as a function of distance along the plasma expansion from 0.5-5.5 mm. The electron temperature and the electron number density were determined from the Boltzmann’s plot method and the Stark broadening methods respectively. From our investigations the electron temperature was evaluated to be in the range of 17556-9785 K for the laser energy of 500 mJ and 17341-8946 K with laser energy of 450 mJ. The electron number density was deduced to be from 1.46 × 1017-1.89 × 1017 cm-3 and 1.29 × 1017-1.78×1017 cm-3 respectively. From our evaluations, we observed that the electron temperature and number density decrease along the distance of the plasma expansion, and also increases with increasing laser energy.

The third order non-linear optical properties of Buckminster fullerene (C60) molecule has been studied using a Nd:YAG laser, in the visible and in the infrared region. The solvent using toluene was specifically used because of low threshold intensity for an optical limiter application. Closed aperture Z-scan technique was adopted to characterize the material due to its simplicity and high sensitivity in measuring the third-order optical nonlinearity. This allows computing the contributions of nonlinear absorption and nonlinear refraction towards nonlinearity. Saturable Absorption (SA) for C60 nano particles is also established. RSA is not established. FT-IR studies is also carried out to characterize the sample and to correlate the NLO studies.

Copper Indium Gallium di-telluride (CIGT) single crystals were synthesized by a special modified Bridgman technique for crystal growth. Our XRD patterns clearly exhibited single phase. The temperature dependence of the electrical conductivity σ(T), Hall coefficient RH(T) in CuInGaTe2 single crystals have been demonstrated over the temperature range 143-558 K for the first time. The Hall coefficient sign confirms the samples displays the p-type conducting. The temperature dependence of the conductivity, Hall coefficient, Hall mobility, and charge carriers concentration were investigated were presented with a clear and effective pictures. CuInGaTe2 single crystals revealed electrical band gaps (or "transport gaps") ranging from 0.64 eV to 0.85 eV. The results obtained from electrical conductivity and carrier concentration revealed the sample p-type with acceptor energy level equal to ≈ 0.027 eV. From the obtained experimental data, the main fundamental physical constants and others for crystals under consideration have been estimated.