Nonlinear Absorption Properties of Cr ₂Ge ₂Te ₆ and Its Application as an Ultra-Fast Optical Modulator

Abstract

In this manuscript, the nonlinear absorption properties of Cr ₂Ge ₂Te ₆ and its application in ultra-fast optical modulation are investigated. Typical parameters, namely, nonlinear absorption coefficient (β), saturation intensity, and modulation depth are measured to be ~1.66 × 10 ⁻⁹ m/W, 15.3 MW/cm ², and 5.8%, respectively. To investigate the feasibility of using the Cr ₂Ge ₂Te ₆ as an ultra-fast optical modulator, a ring-cavity passively mode-locked Er-doped fiber laser has been constructed. The output power/pulse, duration/pulse, and repetition rate/signal-to-noise ratios for the stable mode-locked operation are 2.88 mW/881 fs/19.33 MHz/48 dB, respectively, which proves that the Cr ₂Ge ₂Te ₆ has outstanding nonlinear optical properties and advantages in performing as an ultra-fast optical modulator. Further, the experimental results provide valuable references and open new avenues for developing two-dimensional, material-based, ultra-fast optical modulators and advanced photonic devices based on Cr ₂Ge ₂Te ₆.