Compact nonvolatile 2×2 photonic switch based on two-mode interference
Chunmeng Song, Yixiao Gao, Guoxiang Wang, Yimin Chen, Peipeng Xu, Chenjie Gu, Yaocheng Shi, Xiang Shen
Abstract
On-chip nonvolatile photonic switches enabled by phase change materials (PCMs) are promising building blocks for power-efficient programmable photonic integrated circuits. However, large absorption loss in conventional PCMs (such as Ge 2 Sb 2 Te 5 ) interacting with weak evanescent waves in silicon waveguides usually leads to high insertion loss and a large device footprint. In this paper, we propose a 2×2 photonic switch based on two-mode interference in a multimode slot waveguide (MSW) with ultralow loss Sb 2 S 3 integrated inside the slot region. The MSW supports two lowest order TE modes, i.e., symmetric TE 00 and antisymmetric TE 01 modes, and the phase of Sb 2 S 3 could actively tune two-mode interference behavior. Owing to the enhanced electric field in the slot, the interaction strength between modal field and Sb 2 S 3 could be boosted, and a photonic switch containing a ∼9.4 µm-long Sb 2 S 3 -MSW hybrid section could effectively alter the light transmission between bar and cross ports upon the phase change of Sb 2 S 3 with a cross talk (CT) less than −13.6 dB and an insertion loss (IL) less than 0.26 dB in the telecommunication C-band. Especially at 1550 nm, the CT in the amorphous (crystalline) Sb 2 S 3 is −36.1 dB (−31.1 dB) with a corresponding IL of 0.073 dB (0.055 dB). The proposed 2×2 photonic switch is compact in size and compatible with on-chip microheaters, which may find promising applications in reconfigurable photonic devices.