Fiber Compound Cavity

We present the time dependence, steady state behavior and spectra of a dual fiber-laser compound cavity. This particular cavity is formed with two Er-doped fiber amplifiers, each terminated with a fiber Bragg grating, and coupled through a 50/50 coupler to a common feedback and output coupling element. The experiment and theory show that a low Q, high gain symmetric compound cavity extracts nearly all the incoherent power in a coherent mode when the two fiber polarizations are aligned. This extraction is maintained even when there is significant difference in the optical pathlengths of the two component elements.