Fiber loop reflectors

The theory and application of fiber loop reflectors, fabricated by forming a fiber loop between the output ports of a directional coupler, is described. The reflectivity of the loop is shown to depend upon the coupling characteristics of the coupler and on the degree of birefringence in the fiber loop. Measured loop reflectivities, in terms of wavelength response, coupling ratio, and loop birefringence are shown to agree very well with theory. Two applications of the fiber reflector are briefly discussed; an all fiber laser and a duplex optical communications link using a single light source