Enhanced sensitivity of the Z-scan technique on saturable absorbers using radially polarized beams

We develop the Z-scan technique on a saturable absorber under the excitation of radially polarized beams. It is shown that the sensitivity of the Z-scan measurements on a saturable absorber using radially polarized beams has the great improvement compared with those using the scalar light beams such as Gaussian beams, Laguerre-Gaussian beams, and top-hat beams. As the experimental evidence, we investigate the saturable absorption properties of layered WS2 nanosheets in aqueous suspension by performing the radially polarized-beam Z-scan measurements with femtosecond laser pulses in the near infrared region. (C) 2016 AIP Publishing LLC.