Ultra-compact and low-insertion-loss silicon modal bandpass filter using a pixelated region

In this paper, a silicon modal bandpass filter using a pixelated region, in which the TE1 mode passes through while TE0 and TE2 modes are blocked, is proposed, optimized, and experimentally demonstrated. To achieve low insertion loss, ultra-compact footprint, relatively broad bandwidth and large extinction ratio, the direct-binary-search optimization algorithm and finite difference time domain method are employed to optimize the design of the pixelated region. Measurement results reveal that, for the fabricated filter, an extinction ratio of 16.91 dB and an insertion loss of 0.89 dB are realized at 1550 nm. The measured extinction ratio is larger than 16.03 dB and the insertion loss is lower than 1.04 dB from 1538.5 to 1584.5 nm. Additionally, the length of the pixelated region is only 4.8 mu m.