Abstract

A stable, ultranarrow linewidth diode laser has many uses ranging from precision optical measurements to microwave signal generation and optical communication. A variety of electrical and optical feedback techniques for narrowing laser linewidth have been demonstrated.¹ Rayleigh backscattering from a length of optical fiber can dramatically reduce instantaneous linewidth but it also induces rapid frequency hopping.^2,3 Frequency selective Rayleigh backscattering emitted from a fiber ring resonator, however, allows for similar linewidth reduction without such frequency hopping.⁴ We present for the first time, to our knowledge, quantitative experimental evidence indicating subhertz linewidth and frequency stability using this technique.

© 1992 Optical Society of America