Nonlinear optical properties of two-dimensional palladium ditelluride (PdTe₂) and its application as aerosol jet printed saturable absorbers for broadband ultrafast photonics

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have recently gathered substantial interest in the advanced photonic field due to their strong broadband absorption, tunable bandgap, and excellent nonlinear optical (NLO) properties. Palladium ditelluride (PdTe₂) is a novel TMD material with high carrier mobility, great stability, and narrow bandgap, allowing it to be used in a wide range of applications such as superconductors, phototransistors, and millimeter-wave receivers. Here, the NLO properties of PdTe₂ are investigated by Z-scan technology. The highest nonlinear absorption coefficient of PdTe₂ has been determined as -9.25 × 10³ cm/GW (1 µm) and -0.55 × 10³ cm/GW (1.5 µm), implying its admirable NLO characteristics. Subsequently, for the first time, broadband PdTe₂-based saturable absorbers (SAs) are prepared by utilizing the aerosol jet printing (AJP) method. By employing this PdTe₂ based SA, the generation of broadband ultrafast laser pulses from the near-to-mid-infrared regime with pulse durations in the ps to fs range (170 ps, 570 fs, and 1.59 ps in 1 μm, 1.5 μm, and 2 μm laser sources, respectively) further signify the capability of PdTe₂ as an ideal NLO material for ultrafast photonics devices. Moreover, Q-switched and high-repetition-rate (0.7 GHz) based 58^th harmonic mode-locked pulses in the telecommunication band are also obtained with this SA. These findings indicate that 2D-PdTe₂ is a promising material for nonlinear optics and broadband ultrafast photonics applications.