Saturable absorber mirrors based on layered platinum diselenide

Area of Science:

• Materials Science
• Optics and Photonics
• Condensed Matter Physics

Background:

• Saturable absorber mirrors (SAMs) are essential components in passive mode-locked lasers.
• Two-dimensional (2D) materials possess excellent nonlinear optical (NLO) properties, making them suitable for advanced SAM applications.

Purpose of the Study:

• To investigate the thickness-dependent ultrafast carrier dynamics and NLO properties of platinum diselenide (PtSe2) thin films integrated into 2D SAMs.
• To explore the potential of PtSe2-based SAMs for next-generation mode-locked laser devices.

Main Methods:

• Fabrication of PtSe2 thin films of varying thicknesses directly onto gold mirrors to create 2D SAMs.
• Time-resolved differential reflectance spectroscopy using a 1.55 eV excitation pulse to analyze ultrafast carrier dynamics.
• Pump-probe measurements in a reflective geometry to assess NLO modulation depth and uniformity.

Main Results:

• PtSe2-SAMs demonstrated photoinduced electron-hole pair recombination on the order of hundreds of picoseconds.
• Tunable NLO modulation depth was achieved, ranging from approximately 3.40% to 13.38% with varying PtSe2 film thicknesses.
• Non-destructive uniformity assessment confirmed a low standard deviation in the NLO response across the SAM-mirror surface.

Conclusions:

• The study provides significant insights into the ultrafast and NLO characteristics of PtSe2-based SAMs.
• PtSe2-based 2D SAMs show considerable promise for applications in mode-locked lasers and other photonic devices.