Giant nonlinear optical activity in two-dimensional palladium diselenide

Area of Science:

• Materials Science
• Optoelectronics
• Condensed Matter Physics

Background:

• Layered two-dimensional transition metal chalcogenides are explored for optoelectronics.
• Existing materials have visible-to-ultraviolet bandgaps, limiting narrow-bandgap research.
• Palladium diselenide (PdSe2) offers a near-infrared bandgap for nonlinear optical studies.

Purpose of the Study:

• Investigate nonlinear optical processes in palladium diselenide (PdSe2).
• Explore the unique thickness-dependent nonlinear optical properties of PdSe2.
• Assess the potential of PdSe2 for advanced optoelectronic applications.

Main Methods:

• Comprehensive study of nonlinear optical processes.
• Measurement of second harmonic generation.
• Characterization of two-photon absorption coefficients and modulation depths.

Main Results:

• PdSe2 displays unique thickness-dependent second harmonic generation, unlike other transition metal chalcogenides.
• Two-photon absorption coefficients in 1-3 layer PdSe2 are significantly higher (2-3 orders of magnitude) than conventional 2D materials.
• Giant modulation depths (up to 32%) were achieved in few-layer PdSe2.

Conclusions:

• PdSe2 possesses distinct nonlinear optical characteristics due to its narrow bandgap.
• The material's properties suggest potential for technological innovation in nonlinear optoelectronics.
• PdSe2 is a promising candidate for next-generation optoelectronic devices.