High resolution optical interferometry often requires thermal and acoustic insultation to reduce and remove environment-induced fluctuations. Broader applications of interferometric optical sensors in the future call for low-cost materials with both low thermal diffusivity and good soundproofing capability. In this paper, we explore the feasibility and effectiveness of natural soil as an insulation material for ultrahigh-resolution fiber-optic interferometry. An insulation chamber surrounded by soil is constructed, and its impact on the noise reduction of a Mach-Zehnder Fabry-Perot hybrid fiber interferometer is evaluated. Our results indicate that soil can effectively reduce ambient noise across a broad frequency range. Moreover, compared to conventional insulation materials such as polyurethane foam, soil shows superior insulation performance at low frequencies and thereby affords better long-term stability. This work demonstrates the practicability of soil as a legitimate option of insulation material for precision optical experiments.
Keywords: Fabry-Perot cavity; Mach-Zehnder interferometer; acoustic insulation; fiber optics; optical interferometry; soil; thermal insulation.