Batch Fabrication of High‐Quality Infrared Chalcogenide Microsphere Resonators

Abstract Optical microsphere resonators working in the near‐ and mid‐infrared regions are highly required for a variety of applications, such as optical sensors, filters, modulators, and microlasers. Here, a simple and low‐cost approach is reported for batch fabrication of high‐quality chalcogenide glass (ChG) microsphere resonators by melting high‐purity ChG powders in an oil environment. Q factors as high as 1.2 × 10⁶ (7.4 × 10⁵) are observed in As₂S₃ (As₂Se₃) microspheres (≈30 µm in diameter) around 1550‐nm wavelength. Smaller microspheres with sizes around 10 µm also show excellent resonant responses (Q ≈ 2.5 × 10⁵). Based on the mode splitting of an azimuthal mode in a microsphere resonator, eccentricities as low as ≈0.13% (≈0.17%) for As₂S₃ (As₂Se₃) microspheres are measured. Moreover, by coupling ChG microspheres with a biconical As₂S₃ fiber taper, Q factors of ≈1.7 × 10⁴ (≈1.6 × 10⁴) are obtained in As₂S₃ (As₂Se₃) microspheres in the mid‐infrared region (around 4.5 µm). The high‐quality ChG microspheres demonstrated here are highly attractive for near‐ and mid‐infrared optics, including optical sensing, optical nonlinearity, cavity quantum electrodynamics, microlasers, nanofocusing, and microscopic imaging.