Refractive Third-order Nonlinearity in Vanadium-oxide Phthalocyanine Micro-crystals

Abstract

We report a study on the resonant third-order nonlinear optical response of vanadyl-phthalocyanine micro-crystals. The refractive and absorptive contributions to the nonlinear response at several wavelengths across resonance were determined by employing the z-scan technique with a tunable picosecond pulsed laser source. The samples studied were cyclohexane suspensions of vanadium-oxide phthalocyanine micro-crystals 40 nm in diameter. These micro-crystals represent an interesting alternative for the production of solid state samples of good optical quality through relatively simple techniques. Experimental results show that for wavelengths above 610 nm, the sample presents saturation of absorption, while for shorter wavelengths, induced absorption is found. Around 610 nm however, the absorptive contribution to the nonlinearity vanishes while a finite refractive contribution remains. This wavelength region is therefore potentially useful for all-optical switching applications.

Role of Structural Factors in the Nonlinear Optical Properties of Phthalocyanines and Related Compounds

“…Rare-earth phthalocyanines are novel candidates for optical limiting processes, since they have recently exhibited high excited-state absorption cross sections. [197][198][199][200][201][202][203][204] For example, Eu(IV) and Gd(IV) sandwhich-type derivatives have been recently measured via fluencedependent transmittance measurements. 201 The Eu-Pc 2 exhibits better optical limiting performance probably due to its bigger radius that weakens intramolecular π-π* interaction and, so, increases triplet-state lifetimes.…”

“…Other metallic phthalocyanines that have recently shown good OL performances are the paramagnetic VOPc derivatives. , It appears that the magnetic moments contribute to the spin−orbit coupling and enhance the intercrossing rate. Even though some VOPc derivatives show larger σ ex /σ 0 values than the InClPc( tert -butyl) 4 , the fluence saturation of the former is also larger, which means that less excited-state populations are produced.…”

Third-order nonlinear optical properties of a dmit2−salt by Z-scan technique

“…The nonlinear absorption coefficient ¼ À2:94 cm GW À1 is obtained from the best fitting performed on the experimental data of the open-aperture measurement using equation (3). For the linear dependence of the real and imaginary parts of ð3Þ with concentration of the sample [16], under the same conditions, the calculated results indicate the third-order nonlinear refractive index under 532 nm excitation is 100 times as large as that under 1064 nm excitation. Electron transition, resonant effect and thermal effect will impact the value of the ð3Þ .…”

Non-linear optical properties of composite naphthalocyanine thin films with nanocrystalline morphology

“…Saturable absorbers find applications in Q-Switching and mode-locking, which are techniques employed to obtain short and ultrafast laser pulses of nanosecond and picosecond durations respectively. Based on the previous reports in these materials, an excitation wavelength dependent study would be useful to reveal the spectral region where the non-linearity changes over to a reverse saturable absorption (RSA) behavior, for potential optical limiting applications [13][14][15].…”