Device for measuring refractive index through optical fiber interferometry

The invention discloses a device for measuring a refractive index through an optical fiber interferometry. The device comprises a laser light source, a circulator, a sample reservoir, a photoelectric detector, a demodulation module and a collimator, wherein the collimator is arranged at one end of the sample reservoir; a 10%-reflecting 90%-transmission type lens is arranged in the collimator; a Faraday rotating mirror is arranged at the rear end of the sample reservoir; the light emitted from a laser passes through the collimator, and then becomes parallel light, emits into the sample reservoir and is reflected by the Faraday rotating mirror at the rear end; the Faraday rotating mirror can avoid the interference between the incident light and the reflected light in the sample reservoir; the two paths of light, namely, the reflecting light of the collimator and the reflecting light of the Faraday rotating mirror, have interference phenomenon. The device provided by the invention is high in measuring precision, is simple in structure, is easy to realize miniaturization, can be used for measuring various samples of gas and liquid, is wide in measuring scope of refractive index and can realize the digital automatic measurement.