High efficiency fiber-coupled acousto-optic modulator with low drive power based on Ge21Sb18S61 chalcogenide glass

Acousto-optic modulators (AOMs) are widely utilized in laser Q-switching, optical communications, and spectral analysis. In this work, Ge21Sb18S61 (GeSbS) chalcogenide glass (ChG) was systematically studied as an AO medium. The GeSbS glass exhibits a low thermo-optic coefficient of 16.7 × 10−6 °C−1, a sound velocity of 2674 m/s, an acoustic attenuation of 4.06 dB/cm at 100 MHz, and a high AO figure of merit of 201.1 × 10−18 s3/g. We fabricated a fiber-coupled AOM based on GeSbS glass. It exhibited a high diffraction efficiency of 84.07% at 1.55 μm with an exceptionally low radio frequency drive power of 0.52 W, demonstrating an extinction ratio of 61 dB, an insertion loss of 2.1 dB, and a rise time of 41 ns that met or exceeded those of commercial AOMs. Furthermore, integration of the GeSbS AOM into an all-fiber erbium-doped ring laser enabled stable Q-switching pulsed laser operation with a minimum pulse width of 233 ns at 5 kHz. These results demonstrated the superior AO performance of GeSbS glass, expanding the possibilities for practical applications and the AOM implementation.