Uneven splitting ratio 1 \times 2 multimode interference splitters based on sili

Two types of 1 \times 2 multi-mode interference (MMI) splitters with splitting ratios of 85:15 and 72:28 are designed. On the basis of a numerical simulation, an optimal length of the MMI section is obtained. Subsequently, the devices are fabricated and tested. The footprints of the rectangular MMI regions are only 3 \times 18.2 and 3 \times 14.3 (\mu m). The minimum excess losses are 1.4 and 1.1 dB. The results of the test on the splitting ratios are consistent with designed values. The devices