This paper reports a new model for strained quantum well lasers, which are based on the quantum well transmission line modeling method where effects of both carrier transport and carrier heating have been included. We have applied this new model and studied the effect of carrier transport on the output waveform of a strained quantum well laser both in time and frequency domains. It has been found that the carrier transport increases the turn-on, turn-off delay times and damping of the quantum well laser transient response. Also, analysis in the frequency domain indicates that the carrier transport causes the output spectrum of the quantum well laser in steady state to exhibit a redshift which has a narrower bandwidth and lower magnitude. The simulation results of turning-on transients obtained by the proposed model are compared with those obtained by the rate equation laser model. The new model has also been used to study the effects of pump current spikes on the laser output waveforms properties, and it was found that the presence of current spikes causes (i) wavelength blueshift, (ii) larger bandwidth, and (iii) reduces the magnitude and decreases the side-lobe suppression ratio of the laser output spectrum. Analysis in both frequency and time domains confirms that the new proposed model can accurately predict the temporal and spectral behaviors of strained quantum well lasers.
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http://dx.doi.org/10.1364/AO.55.001518 | DOI Listing |
J Mol Model
January 2025
Department of Chemistry, Federal Institute of Education, Science and Technology of Espírito Santo, Av. Min. Salgado Filho, Vila Velha, 29106-010, Espírito Santo, Brazil.
Context: This study presents quantum chemical analysis of 14 distinct carbon-based nanostructures (CBN), ranging from simple molecules, like benzene, to more complex structures, such as coronene, which serves as an exemplary graphene-like model. The investigation focuses on elucidating the relationships between molecular orbital (MO) energies, the energy band gaps, electron occupation numbers (eON), electronic conduction, and the compound topologies, seeking to find the one that approaches most of a graphene-like structure for in silico studies. Through detailed examination of molecular properties including chemical hardness and chemical potential, we demonstrate that the electronic exchange between orbitals is directly influenced by the structural topology of the carbon-based nanostructures, as the electron occupation numbers and the molecular orbital energies.
View Article and Find Full Text PDFFuture Sci OA
December 2025
Faculty of Medical Sciences, Obstetrics and Gynecology at Lebanese University, Beirut, Lebanon.
Background: Shoulder dystocia, a challenging condition for obstetricians, poses significant risks to both maternal and neonatal health, including maternal postpartum hemorrhage, neonatal hypoxia, and brachial plexus injury. Despite being unpredictable and unpreventable, effective management can mitigate these risks. Miscommunication and poor leadership are responsible for 72% of medical errors, which further highlights the importance of robust leadership skills in obstetric emergencies.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2024
Department of Physics and Engineering, Albany State University, GA 31707. USA. Electronic address:
This work represents a comprehensive study of the ground vibrational state of C-13 substituted methanol using very high-resolution far-infrared (FIR) and infrared (IR) Synchrotron Radiation spectra recorded with a very high signal-to-noise (S/N) ratio in the entire region from 40to5000cm, at the Canadian Light sources. High resolution combined with a high S/N ratio allowed the recording to be done with an unprecedented resolution of about 0.0017cm.
View Article and Find Full Text PDFPhytochemistry
January 2025
Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, People's Republic of China; Laboratory for Marine Drugs and Bioproducts, Qingdao Marine Science and Technology Center, Qingdao, 266237, People's Republic of China. Electronic address:
Two undescribed rearranged diterpenoids, lobopaucinoids A and B (1 and 2), along with thirteen undescribed lobane-type diterpenoids lobopaucinoids C-O (3-15) including a C (11) and two C (12 and 13) undescribed norditerpenoids, were isolated from the soft coral Lobophytum pauciflorum Ehrenberg (Sarcophytidae family) collected from Xisha Islands of the South China Sea. Additionally, two undescribed prenyleudesmane-type diterpenoids, lobopaucinoids P and Q (16 and 17), as well as two known lobane diterpenoids (18 and 19), were also obtained. Their structures were elucidated based on comprehensive spectroscopic data, Mosher's method, Mo(OAc) or Rh(OCOCF)-induced circular dichroism experiment, quantum chemical calculations, and single-crystal X-ray diffraction and literature comparison.
View Article and Find Full Text PDFJ Mol Graph Model
January 2025
Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry of the Russian Academy of Sciences, 1 Academician Semenov Avenue, 142432, Chernogolovka, Russian Federation.
Gas phase bond dissociation energies (BDE) O-H/N-H in hydroquinone (HQ), 4-aminophenol (AP), 1,4-phenylenediamine (PDA), 4-hydroxydiphenylamine (HDPA), N,N'-diphenyl-1,4-phenylenediamine (DPPDA) as well as in their phenoxyl/aminyl radicals have been determined using a combined technique of quantum chemical calculation. The technique included a series of DFT (PBE1PBE, TPSSTPSS, M06-2X), ab initio (DLPNO-CCSD(T)) methods with valence 3ξ-basis sets, composite methods of Gaussian family (G4) and Weizmann theory with ab initio Brueckner Doubles (W1BD), as well as reference reactions of different levels of structural similarity. W1BD method was used in combination with isodesmic reactions for BDE estimation (kJ∙mol) of compounds with the only aromatic fragment: BDE = 352.
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