Large 3rd Order Optical Kerr Nonlinearity in 2D PdSe2 Dichalcogenide
Films for Integrated Nonlinear Photonic Chips
Abstract
As a novel layered noble metal dichalcogenide material, palladium
diselenide (PdSe2) has attracted wide interest due to
its excellent optical and electronic properties. In this work, a strong
third-order nonlinear optical response of 2D PdSe2 films
is reported. We conduct both open-aperture (OA) and closed-aperture (CA)
Z-scan measurements with a femtosecond pulsed laser at 800 nm to
investigate the nonlinear absorption and nonlinear refraction,
respectively. In the OA experiment, we observe optical limiting
behaviour originating from large two photo absorption (TPA) in the
PdSe2 film of β = 3.26 ×10-8
m/W. In the CA experiment, we measure a peak-valley response
corresponding to a large and negative Kerr nonlinearity of
n2 = -1.33×10-15
m2/W – two orders of magnitude larger than bulk
silicon. In addition, the variation of n2 as a
function of laser intensity is also characterized, with
n2 decreasing in magnitude when increasing
incident laser intensity, becoming saturated at
n2 = -9.96×10-16
m2/W at high intensities. Our results show that the
extraordinary third-order nonlinear optical properties of
PdSe2 have strong potential for high-performance
nonlinear photonic devices.