Reduction in the line width of an injection laser by resonant Rayleigh scattering in a fiber ring interferometer

An investigation was made of fiber-optic devices as components of resonator optics of semiconductor lasers. The example of the Mach–Zehnder and ring interferometers is used to demonstrate the effectiveness of the fiber-optic methods in mode discrimination and narrowing of the emission line. An investigation is reported of a semiconductor laser emitting at λ = 1.58 μm and of an external fiber resonator utilizing resonant Rayleigh scattering in a ring fiber interferometer. The laser emission line width is shown to decrease by a factor of at least 2 X 10³. The mechanism of reduction of frequency fluctuations by Rayleigh scattering in a ring interferometer is considered.