Two-dimensional second-order nonlinear optical spectra: landscape of second-order nonlinear optics

Abstract

The landscape of second-order nonlinear optical (2nd NLO) responses of a system can be depicted as two-dimensional second-order nonlinear optical spectra in a range of external fields, and this is difficult to be realized in experiment for a wide range of external fields. In the present study, an efficient method for application of sum-over-states model to simulate electronic two-dimensional NLO (2DNLO) spectra has been developed, and techniques to analyze NLO response-structure correlation have been proposed. This 2DNLO method has been applied to simulate the 2DNLO spectra of a series of typical electron push-pull chromophores under external fields of up to 5.00 eV. The correlation between the NLO properties and structure has been disclosed, and a further strategy to enhance the NLO properties of push-pull chromophores has been proposed.

Spiral Graphene Nanoribbons with Azulene Defects as Potential Nonlinear Optical Materials

“…The other electron excitations with excitation energies larger than 2.05 eV (up to 7.2 eV) contribute approximately 1.4 × 10 –27 esu to the static first hyperpolarizability (⟨β 0 ⟩) of ADSGN8. The ⟨β 0 ⟩ of a typical electron push–pull chromophores (D/A) with polymethine (C 155 O 3 N 4 F 3 H 150 ) was studied with the same methods . The ⟨β 0 ⟩ of C 155 O 3 N 4 F 3 H 150 is 2049.4 × 10 –30 esu (12.4 × 10 –30 esu/heavy-atom), and the ⟨β 0 ⟩ of ADSGN8 (2498.9 × 10 –30 esu, 8.2 × 10 –30 esu/heavy-atom).…”

“…The electronic spectra of the ADSGN segments with up to eight units are predicted. On the basis of the predicted electron transition energy, transition moments, and dipole moments from ZINDO, the first hyperpolarizabilities, including two-dimension second-order NLO spectra , of those ADSGNs are predicted with the sum-overstate model ,, using the code LinSOSProNLO . The two-dimension second-order NLO spectra include all possible second-order NLO responses of a system. , Since the NLO properties from the SOS model are predicted and interpreted based on single electron excitations, the electronic spectra of all systems are predicted and discussed in detail in the following section.…”

“…On the basis of the predicted electron transition energy, transition moments, and dipole moments from ZINDO, the first hyperpolarizabilities, including two-dimension second-order NLO spectra , of those ADSGNs are predicted with the sum-overstate model ,, using the code LinSOSProNLO . The two-dimension second-order NLO spectra include all possible second-order NLO responses of a system. , Since the NLO properties from the SOS model are predicted and interpreted based on single electron excitations, the electronic spectra of all systems are predicted and discussed in detail in the following section. For consistency with the following discussion of electronic spectra and nonlinear optical properties, the electronic density of states (DOS) and the frontier molecular orbitals are plotted based on the ZINDO predictions, and those based on the DFT predictions are provided in the Supporting Information.…”

Tuning the edge states in X-type carbon based molecules for applications in nonlinear optics

“…The consistency of the predicted electronic spectra with the measured one gives the confidence in the electronic spectra prediction of those X-type nanoribbons using ZINDO. The first hyperpolarizabilities (〈 β 〉) are calculated using the LinSOSProNLO program 38,39 based on the sum-over-state (SOS) model 40,41 with improved computational efficiency, 39,42 which can be expressed aswhere ħ is Planck's constant divided by 2π. i , j and k are cartesian coordinate indices.…”

“…To investigate the second order NLO responses in external field, the two-dimensional (2D) second order NLO spectra 42,59,60 of the X 1 -H6, X 4 -CO and other two (NH 2 /NO 2 ) functionalized X 4 -COs are predicted under external fields scanned up to 7.00 eV with a scanning step size of 0.05 eV. The landscapes of the 2D second order NLO spectra of those structures are similar, with a basin located at center surrounded by multiple peaks (Fig.…”