Ultrafast Switching Time and Third Order Nonlinear Coefficients of Microwave Treated Single Walled Carbon Nanotube Suspensions

Abstract

Microwave treated water soluble and amide functionalized single walled carbon nanotubes have been investigated using femtosecond degenerate pump-probe and nonlinear transmission experiments. The time resolved differential transmission using 75 femtosecond pulse with the central wavelength of 790 nm shows a bi-exponential ultrafast photo-bleaching with time constants of 160 fs (130 fs) and 920 fs (300 fs) for water soluble (amide functionalized) nanotubes. Open and closed aperture z-scans show saturation absorption and positive (negative) nonlinear refraction for water soluble (amide functionalized) nanotubes. Two photon absorption coefficient, beta0 approximately 250 cm/GW (650 cm/GW) and nonlinear index, gamma approximately 15 cm2/pW (-30 cm2/pW) are obtained from the theoretical fit in the saturation limit to the data for two types of nanotubes.

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

“…The measured values of FOM are given in Table 2. For all the four graphene suspensions the values of the FOM are comparable with those of single walled carbon nanotube (SWNT) suspensions [17][18] and double walled carbon nanotube (DWNT) suspensions [19]. Under the same experimental conditions as used for OA, no appreciable nonlinear refraction was observed in the closed aperture (CA) Z-scan, similar to the results using ps and ns laser pulses [6].…”