Fine adjustment of cavity loss by fiber optical loop mirror for dual-wavelength laser

We report numerically and experimentally analysis of optic fiber Sagnac interferometer and fine adjustment of cavity loss by the use of the FOLM with a hi-bi fiber in the loop. Changes in transmittance profile amplitude and wavelength shift are caused by the whirl effect in the connectors of a coupler with ports output connected to a birefringent fiber. Also the experimental demonstration of dual wavelength operation of a fiber laser through fine adjustment of cavity loss, using a Fiber Optical Loop Mirror (FOLM) with a high-birefringence fiber in the loop. The reflection and transmission of the FOLM presents a sinusoidal wavelength dependence which can be shifted by controlling the temperature of the hi-bi fiber. A temperature change of the hi-bi fiber by 0.1 degrees C causes a measurable change in the ratio between the reflectance for the wavelengths R(lambda(1))/R(lambda(2)). Using this adjustment be able to change the generation mode from single wavelength to stable dual wavelength generation with equal powers for lambda(1) and lambda(2) or to stable dual wavelength generation with unequal powers at lambda(1) and lambda(2). The change of the ratio between the FOLM reflection R(lambda(1))/R(lambda(2)) allows the investigation of tolerance of dual wavelength generation on the ratio between cavity loss. Was found that for the switch from a single wavelength emission at lambda(1) to single wavelength emission at lambda(2) the ratio R(lambda(1))/R(lambda(2)) has to be changed by the order of magnitude of 10(-2). This value shows the tolerance of the dual wavelength laser to the cavity loss adjustment.