Optical Dynamics of Picosecond Pulse Trains in Aluminum and Zinc Tetracarboxy-Phthalocyanines

Abstract

The nonlinear properties and photophysical dynamics of aluminum and zinc tetracarboxy-phthalocyanines (AlPc and ZnPc) were studied using pulse trains of a 532 nm wavelength, which contain 25 subpulses with a 100 ps width and 13 ns spacing. Considering its interaction with long-duration pulses, the energy structure of phthalocyanine could be substituted by a five-level pattern. The nonlinear transmissions of pulse trains in AlPc and ZnPc were simulated by means of equations about the population rate coupled with the paraxial field equation of two-dimensional space. The well-known Crank–Nicholson numerical method was applied to the theoretical simulation. The results demonstrate that both phthalocyanines are efficient as optical limiters. In its low-intensity region, AlPc shows a much better OL effect than ZnPc. But in the region with high intensity, their energy transmittances are nearly the same. The nonlinear transmission of a pulse is susceptible to the state lifetime and cross section of one-photon absorption. Tetracarboxy-phthalocyanines have advantageous photophysical properties for applications in nonlinear optical areas, such as nonlinear optical devices like optical limiters. Adding central metals such as Al and Zn to phthalocyanines could enhance their photodynamic properties, making them potential optical limiters and photosensitizers.

Keywords

• optical limiting
• phthalocyanine
• rate equations
• paraxial field equation
• pulse train