Study of nonlinear optical properties of pure and Mg-doped ZnO films

Abstract

We report the nonlinear optical properties in pulsed laser deposited pure and Mg‐doped ZnO films at an excitation energy (≈1.95 eV) much smaller than the band gap energies (≥3.24 eV) of the films. The nonlinear absorption is attributed to the presence of defect states whereas the nonlinear refraction arises due to thermal lensing effect. Larger contribution of nonlinear absorption compared to nonlinear refraction suggests the utility of Mg‐doped ZnO films in optical limiting device applications.

The Third-Order Nonlinear Optical Properties in Cobalt-Doped ZnO Films

“…Therefore the optical nonlinear response of Co-doped ZnO is enhanced for films deposited at relatively low oxygen partial pressure. Our experi-077801-3 mental results agree with the previous findings [20,21] that the defects-associated energy levels within the band gap formed in the sputtering growth at lower oxygen partial pressure can greatly enhance the optical nonlinear response of Co-doped ZnO thin films. In conclusion, we have investigated the third-order optical nonlinear response of Co-doped ZnO films prepared by the magnetron sputtering method by performing both open-aperture and closed-aperture Zscan measurements with a femtosecond pulsed laser at 875 nm.…”

“…A broad, defect-associated PL response located in the range of 450-610 nm is collected, indicating a large number of defects existing in the ZnO films. It has been pointed out that optical nonlinearity of ZnO was associated with the oxygen vacancies [20] or other energy levels located in the band gap. [21] Assisted by the energy levels within the band gap, the optical dipole oscillator strength is increased with the broadening of the excitonic ab-sorption.…”

Green synthesis of silver/silica nanocomposite in seconds at room temperature using reducing agents obtained from silicon nanoparticles

“…The two-photon absorption process has also been reported as a dominant mechanism for the observed nonlinearity in Ag NPs [21]. The measured value of the Ag/SiO 2 nanocomposite two-photon absorption coefficient is compared with recently reported values of the two-photon absorption of different materials [13,[22][23][24][25][26] and are listed in table 1. By adding the SiO 2 NPs into the Ag NPs colloid, the nonlinear absorption coefficient can be improved.…”

Thermo-optic coefficient of chemical vapor deposited graphene multilayers

“…Hence, the evolution of the thermal lens effect is also a medium characteristic. The thermally induced refractive index can be expressed in the form [Boyd (2003); Agrawal et al, (2015)]; where no being the refractive index in linear regime, Δθ = (θ -θo) denotes the enhancement in local temperature of the illuminated portion within the sample, θo being the room temperature (300 K) and θ is the total local temperature.…”