Utilizing the inverse design method of nonlinear direct-binary-search (DBS) optimization algorithm, we designed an ultra-compact broadband high-order mode filter on silicon-on-insulator wafer. The incident TE0 mode is prohibited to pass through the high-order mode filter while the TE1 mode can pass with low insertion loss. The footprint of this mode filter is only 1.56 μm × 2.4 μm. Numerical simulation shows that the insertion loss of this mode filter is lower than 0.26 dB and the extinction ratio is lower than 24.5 dB in the wavelength range from 1500 nm to 1600 nm. The insertion loss at the centre wavelength of 1550 nm is only 0.18 dB.

We propose and experimentally demonstrate a silicon based ultra-compact and low loss higher order mode bandpass filter (HMF), which was inversely designed by a direct-binary search topology optimization algorithm. The proposed HMF is a directional coupler with optimally positioned etched circular air holes in the coupling region which footprint is only 1.8 × 3 μm2. The experimental results show that the HMF has low insertion loss of <1 dB and low crosstalk of <−15 dB in the wavelength range of 1520 ∼ 1580 nm. It can be extended to selectively pass other higher order modes.

No abstract

No abstract