Nonlinear optical and optical limiting studies of alkoxy phthalocyanines in solutions studied at 532 nm with nanosecond pulse excitation

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2008-04, Vol.91 (1), p.149-156
• Main Authors: Venkatram, N., Narayana Rao, D., Giribabu, L., Venugopal Rao, S.
• Format: Article
• Language: English
• Subjects: Apertures; Beam trapping, self-focusing and defocusing; self-phase modulation; Constraining; Engineering; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lasers; Nanosecond pulses; Nonlinear optics; Nonlinearity; Optical Devices; Optical materials; Optical properties; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Polymers and organics; Quantum Optics; Wavelengths
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-008-2934-5

We report our results on the nonlinear optical and optical limiting properties of two alkoxy phthalocyanines namely 2,3,9,10,16,17,23,24-octakis-(heptyloxy) phthalocyanine and 2,3,9,10,16,17,23,24-octakis-(heptyloxy) phthalocyanine zinc(II) studied at a wavelength of 532 nm using 6 ns pulses. Using the standard Z-scan technique we observed that both the phthalocyanines exhibited negative nonlinearity as revealed by the signature of closed aperture data. The magnitude of the nonlinear refractive index n 2 evaluated from the closed aperture data was ∼ 1.61×10 -11  cm 2 /W for the free-base phthalocyanine and ∼ 1.56×10 -11  cm 2 /W for the metallic phthalocyanine. Open aperture Z-scan data indicates strong nonlinear absorption in both the phthalocyanines with measured nonlinear coefficients of ∼ 1650 cm/GW and ∼ 1850 cm/GW respectively. We also report optical limiting properties of these phthalocyanines with limiting thresholds (I 1/2 ) of ∼ 0.5 J/cm 2 . Our studies suggest that these phthalocyanines are one of the best molecules for nonlinear optical applications studied recently.