Influence of laser and material parameters on two photon absorption in Rhodamine B and Rhodamine 6G solutions in MeOH

TPA is known to be a highly sensitive process. Open aperture Z-scan technique has been employed to measure two photon absorption cross section (TPCS) of Rhodamine B and Rhodamine 6G solutions in MeOH. An in depth analysis is carried out to assess the influence of medium as well as laser parameters on TPCS and relative TPA trends. The explored laser parameters are laser energy and pulse width. The varying medium parameters are dye solution concentrations and sample length (cuvette size). True value of TPCS is found to be independent of change in laser energy and pulse width (laser intensity). However, relative TPA is enhanced by increasing pulse energy due to increased transition probability. Shorter pulse width resulted in reduced TPA due to saturation effects. Increase in solution concentration has decreased TPCS due to agglomeration effects. An increase in TPCS with increased sample length is observed owing to an overall increase in TPA absorbers.