Simultaneous reverse saturable absorption of fluorinated naphthalocyanines at 532 and 1064 nm

The series of (tert-butyl)catechol substituted fluorinated naphthalocyanines 1, 2 and 3 display limiting of the optical power generated with nanosecond light pulses simultaneously at 532 an 1064 nm. Limiting thresholds of 1-3 fall in the range 1.5-2.7 J cm-2 at 532 nm and 2.6-3.7 J cm-2 at 1064 nm when linear transmittance is 0.75 at both wavelengths of analysis. Compared to other unsubstituted naphthalocyanines, 1-3 show a relatively large window of high linear optical transmission between the chararacteristic Q- and B- absorption bands (above 0.75 for a 250 nm wide window when 1-3 concentration is in the order of few millimoles per liter in 1 cm thick cells). A general enhancement of photostability in these systems is observed for the presence of electron-withdrawing fluoride substituents. The optical limiting effect produced by these systems is evaluated for the protection of optical sensors which operate in both visible and NIR spectral ranges, e.g. the human eye and night vision devices.