Brief review of the present status of the Sagnac interferometer using high-birefringence optical fibers

We describe the evolution of the high birrefringent fiber Sagnac interferom eter. This contribution shows the most important works, necesary to underst and such interferometer. We mention the first works in which were used opti cal fiber and the recet works in which are using all liber Sagnac interfero meter. Also, we mention the topics related with the study and development o f this interferometer.