Hybrid integration of two-dimensional dichalcogenides for low power saturable absorption in photonic integrated circuits

Silicon photonics provides a versatile platform for large-scale integration of optical functions, but its weak intrinsic nonlinear response limits the realization of active, intensity-dependent functionalities. Hybrid integration of two-dimensional (2D) materials has emerged as a promising strategy to overcome these limitations by enabling strong light--matter interaction and broadband absorption. Here, we demonstrate saturable absorption in a Complementary Metal-Oxide-Semiconductor (CMOS)-compatible silicon-on-insulator (SOI) microring resonator integrated with an exfoliated monolayer of 1T'-MoTe2. Transmission measurements under varying input powers reveal a clear nonlinear absorption response, with a saturation power as low as 2(1)uW. A phenomenological model accurately reproduces the experimental results, confirming the nonlinear behavior induced by the hybrid MoTe2 integration. These findings establish a proof-of-concept for ultracompact, low-power saturable absorbers in photonic integrated circuits (PICs), paving the way for applications in integrated lasers, ultrafast optical signal processing, and neuromorphic photonics.