Experimental confirmation of phase relationships of multimode interference splitters using a shearing-type near-field Sagnac interferometer

We report, for the first time, the experimental confirmation of the phase relationships between the output images of 1/spl times/4 and 1/spl times/8 multimode interference (MMI) splitters. Interference data is obtained using a shearing type near-field Sagnac interferometer. A Fourier transform technique is used to extract the phase information of the splitter output images. Excellent agreement between the experimental results and the theoretical predictions is obtained, which indicates good phase performance of the device.