Enhanced Ultrafast Nonlinear Optical Response in Ferrite Core/Shell Nanostructures with Excellent Optical Limiting Performance. Issue 6 (11th January 2018)

• Record Type: Journal Article
• Authors: Perumbilavil, Sreekanth; López‐Ortega, Alberto; Tiwari, Gaurav Kumar; Nogués, Josep; Endo, Tamio; Philip, Reji
• Is Part Of: Small. Volume 14:Issue 6(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-01-11
• Subjects: core/shell nanoparticles -- nonlinear absorption -- optical limiting -- oxide heterostructures; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201701001
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Nonlinear optical nanostructured materials are gaining increased interest as optical limiters for various applications, although many of them suffer from reduced efficiencies at high‐light fluences due to photoinduced deterioration. The nonlinear optical properties of ferrite core/shell nanoparticles showing their robustness for ultrafast optical limiting applications are reported. At 100 fs ultrashort laser pulses the effective two‐photon absorption (2PA) coefficient shows a nonmonotonic dependence on the shell thickness, with a maximum value obtained for thin shells. In view of the local electric field confinement, this indicates that core/shell is an advantageous morphology to improve the nonlinear optical parameters, exhibiting excellent optical limiting performance with effective 2PA coefficients in the range of 10 −12 cm W −1 (100 fs excitation), and optical limiting threshold fluences in the range of 1.7 J cm −2 . These values are comparable to or better than most of the recently reported optical limiting materials. The quality of the open aperture Z‐scan data recorded from repeat measurements at intensities as high as 35 TW cm −2, indicates their considerably high optical damage thresholds in a toluene dispersion, ensuring their robustness in practical applications. Thus, the high photostability combined with the remarkable nonlinear optical properties makes these nanoparticles excellent candidates for ultrafast optical limiting applications. Abstract : Ultrashort laser pulse (100 fs) excitation of spinel‐based core/shell nanoparticles reveals a nonmonotonic variation of the effective two‐photon absorption coefficient, with a maximum value seen for relatively thin shells. Considering local field enhancement effects, nonlinear transmission studies and finite‐difference time‐domain simulations indicate that core/shell is an advantageous morphology to improve the nonlinearity of the composite for applications like ultrafast optical limiting.