Optical fiber power-splitter with selectable splitting ratio

An optical fiber power-splitter using a thin phase grating is described. Special attention is paid to the wave-length dependency, the insertion loss, and the splitting ratio. By feedback of the output signal, a variety of splitting ratios can be obtained despite the use of a very simple (but highly efficient) grating with a low splitting factor. Experiments were performed with a simple nonoptimal biphase grating confirming the theoretical description. Double passing of the grating results in a selectable splitting ratio of 3, 5, 7, or 9 with a nonuniform power-level distribution for the splitting ratios 5 and 7. Wavelength dependency is hardly restrictive for the applications that can be foreseen for these devices.