Athermal Forward Stimulated Brillouin Scattering

Abstract Forward‐stimulated Brillouin scattering (FSBS) in optical waveguides is a nonlinear optical effect that involves the acousto‐optic interaction between co‐propagating light and guided acoustic waves, showcasing significant potential for applications in integrated photonic and sensing fields. However, the resonance frequency of guided acoustic waves stimulated by FSBS is highly sensitive to fluctuations in ambient temperature, leading to uncertainty in the frequency evaluation of the FSBS system. Herein, the novel mechanism of “athermal FSBS” is proposed, where the resonance frequency remains unaffected by temperature variations. Through simulation and experimentation, the FSBS spectra characteristics of aluminum‐coated optical fiber are demonstrated to be insensitive to temperature fluctuations when the ratio of the radius of the silica to the thickness of the aluminum is ≈2.21; at this point, the temperature dependence of the acoustic velocity of the aluminum coating is precisely counterbalanced with that of the cladding material. Meanwhile, this research confirms that the temperature property of the central frequency of FSBS spectra in aluminum‐coated fibers can be controlled by modulating the optomechanical interaction. Thermally stabilized aluminized waveguides are expected to be utilized in athermal fiber lasers, filters, and on‐chip silicon waveguides, thereby advancing the progression of FSBS in the integrated photonics domain.