L-band femtosecond fiber laser with Cu2Te-PVA thin film

For the first time, this research proposed a copper telluride (Cu2Te)-polyvinyl alcohol thin film as a saturable absorber (SA) in an erbium-doped fiber laser (EDFL) operating in the long-wavelength band (L-band). The nonlinear optical absorption measurement of Cu2Te thin film revealed a saturation intensity of 3.26 kW cm−2 and a modulation depth of 2.7%. Furthermore, the mode-locked pulse was successfully generated by integrating a Cu2Te thin film into the L-band cavity at a threshold pump power of 135.61 mW with a center wavelength and pulse duration of 1565.48 nm and 770 fs, respectively. When observing the output mode-locked pulse, the pump power for the EDFL ranged from 135.61 mW to 201.28 mW, with the fundamental mode having a repetition rate 10.28 MHz. Furthermore, the magnitude of the signal-to-noise ratio was approximately 61.3 dB, indicating that the laser was stable with no significant fluctuations during the stability test. Overall, the findings showed that Cu2Te thin film has an excellent output and a promising candidate for an SA, implying that it could have a lot of potentials in pulsed laser application.

Synthesis, Vibrational Spectroscopy and Optical Study of Bi-Tetrabutylphosphonium Hexachlorostannate

The single crystals of bi-tetrabutylphosphonium hexachlorostannate were grown by solvent evaporated method and characterized by X-ray powder diffraction, Raman spectroscopy and optical study. The X-ray powder diffraction indicates that it was crystallized in the monoclinic system, with C2/c space group. Besides, temperature-controlled X-ray diffraction show that the [P(C4H9)4]2SnCl6 compound indicate the presence of two phase transitions detected at 388 and 403 K. The evolution of Raman line shifts, “ν”, and the half-width, “Δν”, versus temperature show some singularities associated with the transitions, suggesting the important role of the anionic parts ((SnCl6)2-). Besides, the results of the Raman study confirms the conclusion drawn from the X-ray powder diffraction measurements that the phase transition are located near 388K and 403K.Furthermore, an optical absorption measurement confirms the semiconductor nature with a band gap equal to 3.46eV.

Size-Dependent and Enhanced Photovoltaic Performance of Solar Cells Based on Si Quantum Dots

Recently, extensive studies have focused on exploring a variety of silicon (Si) nanostructures among which Si quantum dots (Si QDs) may be applied in all Si tandem solar cells (TSCs) for the time to come. By virtue of its size tunability, the optical bandgap of Si QDs is capable of matching solar spectra in a broad range and thus improving spectral response. In the present work, size-controllable Si QDs are successfully obtained through the formation of Si QDs/SiC multilayers (MLs). According to the optical absorption measurement, the bandgap of Si QDs/SiC MLs shows a red shift to the region of long wavelength when the size of dots increases, well conforming to quantum confinement effect (QCE). Additionally, heterojunction solar cells (HSCs) based on Si QDs/SiC MLs of various sizes are presented and studied, which demonstrates the strong dependence of photovoltaic performance on the size of Si QDs. The measurement of external quantum efficiency (EQE) reveals the contribution of Si QDs to the response and absorption in the ultraviolet–visible (UV-Vis) light range. Furthermore, Si QDs/SiC MLs-based solar cell shows the best power conversion efficiency (PCE) of 10.15% by using nano-patterned Si light trapping substrates.

Photo-induced effects on amorphous and liquid selenium by pulsed laser illumination

Amorphous and liquid selenium exhibit interesting photo-induced changes due to photo-flexibility of lone-pair semiconductors. This study conducts a detailed investigation of the photo-structural changes in amorphous and liquid selenium. We performed photo-induced optical absorption measurement of amorphous and liquid selenium using a nanosecond pulsed laser with a weak intensity of 1.0 mJ/pulse. The measurement indicated photo-induced absorption in the time region from 10−7 to 10−2 s in both amorphous and liquid selenium, which is referred to as fast photodarkening. This suggests a local structural change around a Se atom, such as a formation of three-fold coordination, which produces branched chains in the network, and deviations in the bond angle and dihedral angles. Durable photodarkening, which is semi-permanently preserved after prolonged light illumination, can be attributed to the local structure; however, it also requires an extended network structure. Our findings yield a profound insight into a variety of photo-induced structural changes in a network of selenium chains.

Synthesis and Characterization of Pure and Magnesium (Mg) Doped CuO Nano Particles by Solid State Method

Pure and Magnesium (Mg) doped CuO nanoparticles were effectively prepared by solid state method using Copper Chloride (CuCl2 · 2H2O), Magnesium Chloride (MgCl2 · 6H2O) and Sodium Hydroxide (NaOH). The ITO/TiO2/CuO–M/Cu heterojunctions solutions were fabricated by Dr Blade method at a low reaction temperature of 400 °C. In this analysis the prepared nanostructure were exposed to structural, morphological and optical analysis. The X-ray diffraction peaks results divulged that the prepared nanoparticles are monoclinic structure of CuO which was evidenced from the JCPDS card No. 801916. Morphological analysis result exposed that pure CuO particles exclusively consist of agglomerated irregular spherical shape. The result of the elemental analysis confirmed the presence of Mg2+ in the doped samples. Fourier Transform Infra-Red Spectroscopy results reveals the structural modifications due to the presence of magnesium. Optical absorption measurement spectra demonstrates that band gap shift is due the proportion of Mg.

Cavity-enhanced detection of transient absorption signals

We present a simple, high-duty-cycle, cavity-enhanced optical absorption measurement technique based on delay-limited Pound-Drever-Hall (PDH) sideband locking. The chosen circuit naturally provides realtime readout of the amplitude quadrature of the PDH error signal, which can be mapped onto the cavity’s internal loss rate while using the phase quadrature to lock sideband frequency to the cavity mode. Our proofof-concept device comprises a 5-cm-long Fabry-Perot cavity with a 450 kHz bandwidth (finesse 6800, 350 ns power ringdown), and a feedback bandwidth of several MHz, limited primarily by the group delay of our electronics. This technique could readily be applied to other optical resonators such as fiber cavities, with potential applications in radiation dosimetry.

Polyethylene/Graphene Nanoplatelet Nanocomposite-Based Insulating Materials for Effective Reduction of Space Charge Accumulation in High-Voltage Direct-Current Cables

We have demonstrated a straightforward hydrophobic surface modification of graphene nanoplatelets (GNPs) through a defect-healing process to fabricate well-dispersed insulating low-density polyethylene (LDPE)/GNP nanocomposites and have confirmed their effective suppression of space charge accumulation. Without any organic modifiers, GNPs containing oxygen-based functional groups at the edges were successfully reduced at optimal high-temperature defect-healing condition and modified to have hydrophobic surface properties similar to those of the LDPE matrix. The degree of dispersion and the reproducibility of the mechanically melt-mixed LDPE/GNP nanocomposites were immediately analyzed by thickness-normalized optical absorption measurement. In the LDPE matrix, below the percolation threshold concentration, well-dispersed GNP fillers effectively acted as trapping sites under high electric fields, resulting in the successful suppression of packet-like space charge accumulation (field enhancement factor=1.04 @ 0.1 wt% LDPE/GNP nanocomposite).

First-generation antipsychotic haloperidol: optical absorption measurement and structural, electronic, and optical properties of its anhydrous monoclinic crystal by first-principle approaches

Application of the Density Functional Theory for the structural, electronic and optical properties of haloperidol crystal.