Atomic and Molecular Physics, and Optics, Physics and Astronomy
39
Scopus Publications
Scopus Publications
Generation of isolated attosecond pulses in CdS semiconductor using polarization gating technique and tailored two-color pulse system Amin Sadeghifaraz, Elnaz Irani Scientific Reports, 2025 This research uses a two-color pulse system and polarization gating technique to generate single attosecond pulses from femtosecond laser interaction with cadmium sulfide semiconductor. The rotating elliptical polarization two-color pulse system is designed to produce attosecond pulses up to 420 as. Also, the intensity of the single attosecond pulse can be improved by using a two-color-polarizing gate technique. In this presented modifications, the isolated attosecond pulse with greater intensity and a shorter time width of about 400 as is generated. Generation of such an intense isolated attosecond pulse is a great achievement that helps for measuring the ultrafast phenomena.
Controlling isolated attosecond pulse generation in MoSe2 using polarization gating and TDDFT simulations Erfan Heydari, Elnaz Irani, Ahmadreza Madhani, Mohammad Monfared Scientific Reports, 2025 The dependence of high harmonic generation spectra in solids on the driving wavelength remains an open question, especially regarding its impact on the generation of isolated attosecond pulses. Achieving active control over isolated attosecond pulse generation remains challenging due to the complex dynamics underlying solid-state high harmonic generation. In this work, we investigate high harmonic generation and the corresponding attosecond pulses generated from monolayer molybdenum diselenide using a real-time, ab initio time-dependent density functional theory approach. Our results reveal a linear increase in harmonic cutoff energy with driving wavelength, both parallel and perpendicular to the laser polarization direction. Using a polarization gating technique with symmetric amplitude components, we evaluate attosecond pulse isolation across multiple wavelengths and identify 2.5 [Formula: see text] as the most favorable for generating clean isolated attosecond pulses. Momentum-resolved electron dynamics reveal conditions that favor isolated pulse formation at 2.5 [Formula: see text]. Furthermore, by applying an asymmetric polarization gating at this optimal wavelength, isolated attosecond pulses with favorable temporal confinement are achieved. This study provides insight into wavelength-dependent control of high harmonic generation and efficient isolated attosecond pulse generation in solids.
Substrate-Dependent Characteristics of CuSbS2 Solar Absorber Layers Grown by Spray Pyrolysis Samaneh Shapouri, Elnaz Irani, Payam Rajabi Kalvani, Stefano Pasini, Gianluca Foti, Antonella Parisini, Alessio Bosio Coatings, 2025 Copper antimony sulfide (CuSbS2) is an affordable and eco-friendly solar absorber with an optimal bandgap and high absorption coefficient, and it stands out as a promising candidate for thin-film solar cells. This study investigates the effects of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and glass substrates on the microstructural, morphological, and optical properties of CuSbS2 (CAS) layers synthesized via spray pyrolysis. X-ray Diffraction (XRD) and Raman spectroscopy analyses revealed that CAS phases formed on ITO and FTO substrates exhibited a phase composition without additional copper phases. However, the CAS layer on glass contained a copper sulfide (CuS) phase, which can be detrimental for solar cell applications. Furthermore, the influences of the substrate morphology and contact angle on the growth mechanisms of CAS layers was examined, highlighting the relationship between the substrate micromorphology and the resultant film characteristics. Advanced image processing techniques applied to Atomic Force Microscopy (AFM) images of the substrate surfaces facilitated a comprehensive comparison with the surface characteristics of the CAS films grown on those substrates. Field Emission Scanning Electron Microscopy (FESEM) indicated that CAS layers on ITO possessed larger grains than FTO, whereas those on FTO exhibited lower roughness with a more uniform grain distribution. Notably, the optical properties of the CAS layers correlated strongly with their microstructural and morphological characteristics. This work highlights the critical influence of substrate choice on the growth and characteristics of CAS layers through a comparative analysis.
Generation of the isolated highly elliptically polarized attosecond pulse using the polarization gating technique: TDDFT approach Ahmad Reza madhani, Elnaz Irani, Mohammad Monfared Optics Express, 2023 This paper theoretically investigates the generation of isolated elliptically polarized attosecond pulses with a tunable ellipticity from the interaction of Cl2 molecule and a polarization-gating laser pulse. A three-dimensional calculation based on the time-dependent density functional theory is done. Two different methods are proposed for generating elliptically polarized single attosecond pulses. The first method is based on applying a single-color polarization gating laser and controlling the orientation angle of the Cl2 molecule with respect to the polarization direction of the laser at the gate window. An attosecond pulse with an ellipticity of 0.66 and a pulse duration of 275 as is achieved by tuning the molecule orientation angle to 40° in this method and superposing harmonics around the harmonic cutoff. The second method is based on irradiating an aligned Cl2 molecule with a two-color polarization gating laser. The ellipticity of the attosecond pulses obtained by this method can be controlled by adjusting the intensity ratio of the two colors. Employing an optimized intensity ratio and superposing harmonics around the harmonic cutoff would lead to the generation of an isolated, highly elliptically polarized attosecond pulse with an ellipticity of 0.92 and a pulse duration of 648 as.
Investigation of parameters affecting the high harmonic generation from monolayer WS2 Amin Sadeghifaraz, Elnaz Irani, Mohammad Monfared International Journal of Quantum Chemistry, 2023 The effect of crystal symmetry in the high harmonic generation of monolayer WS2 is investigated using the three‐dimensional time‐dependent density functional theory. The role of linearly and elliptically polarized laser, as well as the crystall orientation in the enhancement of harmonics yield, is explored. Also, the wavelength dependence of the harmonic yield and the intensity dependence of cutoff harmonic order are studied. The former shows an exponential decay with increasing the driving laser wavelength, and the latter reveals a linear dependency of cutoff harmonic to the driving laser field. Moreover, a dual pulse system as a driving laser, a fundamental 1.3 μm laser pulse synthesized by its second harmonic, is proposed which could increase the cutoff harmonic order up to 24th (22 eV). Our results pave the way for controlling and enhancing high harmonic spectra from solids.
Influence of coherent vibrational excitation on the high-order harmonic generation of diatomic molecules Mohammad Monfared, Elnaz Irani, Christoph Lemell, Joachim Burgdörfer Physical Review A, 2022 The generation of high harmonics (HHG) in atomic systems by the highly non-linear response to an intense laser field is a prominent pathway to the synthesis of ever shorter laser pulses at increasingly higher photon energies. Extensions of this process to molecules add to the complexity but also offers novel opportunities as multi-center effects and the coupling to nuclear degrees of freedom can influence HHG. In this work we theoretically explore the impact of coherent vibronic excitations of diatomic molecules on the HHG spectrum within the framework of time-dependent density functional theory. We observe the appearance of novel interference structures in the HHG spectra controlled by resonances between the driving field and the vibronic wavepacket.
Optical absorption and electronic spectra of chlorophylls a and b Leila Hedayatifar, Elnaz Irani, Mahmood Mazarei, Soroush Rasti, Yavar T. Azar, Ali T. Rezakhani, Alireza Mashaghi, Farzaneh Shayeganfar, Mehrnaz Anvari, Tiam Heydari, Ali Rahimi Tabar, Nasser Nafari, Mohammad Ali Vesaghi, Reza Asgari, Mohammad Reza Rahimi Tabar Rsc Advances, 2016
