We propose using a frequency-modulated laser in a fiber-optic gyroscope (FOG) in a minimum configuration. Compared to the traditional broadband source, a narrow-band laser offers two significant advantages, namely the elimination of excess noise and thus improved sensitivity to rotation, and a more stable mean wavelength, hence a greater scale-factor stability. We show that the strong back-reflection and coherent backscattering noise introduced by the use of a laser is greatly reduced by modulating the laser frequency. In both a conventional FOG and in a FOG using an air-core fiber, we demonstrate experimentally that this technique reduces these two sources of noise by at least a factor of 4 compared to the same gyros operated with an unmodulated laser.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.