Ultrafast nonlinear optical properties of alkyl-phthalocyanine nanoparticles investigated using Z-scan technique

Abstract

We report our results on the femtosecond nonlinear optical studies of alkyl-phthalocyanine nanoparticles dispersed in water and dissolved in chloroform. Nonlinear refractive and absorptive properties were investigated using the closed and open aperture Z-scan techniques. The nonlinear optical coefficients obtained for nanoparticles suspended in water are compared with those dissolved in chloroform, which resulted in simple phthalocyanine solutions. Our studies clearly demonstrate the nonlinear refractive index of nanoparticles to be positive, while that of the nanoparticles in chloroform was negative. Our results and analysis point out a high nonlinearity in the ultrafast domain for both the nanoparticles and solutions indicating their potential in optical signal processing and limiting applications.

Ultrafast Nonlinear Optical and Optical Limiting Properties of Phthalocyanine Thin Films Studied Using Z-Scan

“…Table 2 summarizes the nonlinear coefficients of all the films extracted from the present study. The high nonlinearity of PC3 compared to other phthalocyanines can be ascribed to the asymmetry in structure compared to other symmetrical phthalocyanines and is consistent with our earlier results [28][29][30][31][32][33]. Metal phthalocyanine films exhibited higher nonlinearities when compared to free base phthalocyanine films for both alkyl and alkoxy cases whereas alkoxy phthalocyanine films displayed higher nonlinearity compare to alkyl phthalocyanine films.…”

“…The complete details of synthesis of these mole- cules, their molecular structure, and their detailed absorption spectra are reported in our earlier publications [28][29][30][31][32][33]. All the molecules were purified prior to thin film fabrication achieved through spin coating.…”

“…We have recently reported the NLO studies of novel phthalocyanines using continuous wave (cw), nanosecond (ns), picosecond (ps), and femtosecond (fs) laser pulses [25][26][27][28][29][30][31][32][33]. Our recent efforts have been towards understanding the nonlinearities in all the time domains, albeit in solution form.…”

Enhanced optical limiting behaviour of indium phthalocyanine derivatives when in solution or embedded in poly(acrylic acid) or poly(methyl methacrylate) polymers

“…A suitable nonlinear absorber for optical limiting application will exhibit a nonlinear absorptive profile known as reverse saturable absorption (RSA), as it moves along the z-axis through the beam focus. Generally, nonlinear absorptive materials that exhibit an RSA property are important for optical limiting application [1][2][3][4][5][6][7]9,[20][21][22]]. An RSA process will show a transmittance versus z-position signal that is symmetric about the focus (zero position), as shown for the investigated samples in Fig.…”

“…There exists a rather extensive literature on optical limiting materials for sensor protection [1][2][3][4][5][6][7][8]. All of these materials rely on optical nonlinearities, and use a variety of nonlinear mechanisms, which include nonlinear absorption (NLA), nonlinear refraction (NLR), induced scattering, and phase transitions [1].…”