A low power and compact thermo-optic switch based on $1\times 1$ Mach-Zehnder interferometer structure is demonstrated with the thermal isolation structure fabricated with a new backside etching process. The adjacent SiO₂ and underlying silicon around phase arm are removed to suppress the thermal diffusion. Benefiting from the backside anisotropic etching process and front protecting photoresist used in underlying silicon removal, there are no support SiO₂ beams in air trenches avoiding about 10% of extra thermal diffusion. At 1550 nm for TE mode, a low switching power (P $_{\pi } $ ) 0.48 mW is obtained with $450~\mu \text{m}$ thermo-optic interaction length ( $\text{L}_{\mathrm {TO}}$ ) representing a $\text{P}_{\pi }\cdot \text {L} _{\mathrm {TO}}$ product of only $0.22~\text {mW} \cdot \text {mm}$ , indicating a high thermal efficiency with a compact footprint. The 10% - 90% response time of the switch is $530~\mu \text{s}$ , including a rise time of 150 $\mu \text{s}$ , and a fall time of $380~\mu \text{s}$ . Compared with the switch without isolation structure, the switching power of the proposed switch is reduced more than 17 times, needing only 5.6% of the original value.

中文翻译：

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基于悬臂式无支撑梁的低功耗紧凑型硅热光开关

一种低功耗紧凑型热光开关 $1\乘以 1$ Mach-Zehnder 干涉仪结构展示了采用新的背面蚀刻工艺制造的热隔离结构。相邻的SiO ₂和相臂周围的下层硅被去除以抑制热扩散。受益于背面各向异性蚀刻工艺和用于去除底层硅的正面保护光刻胶，空气沟槽中没有支撑 SiO ₂梁，避免了约 10% 的额外热扩散。对于 TE 模式，在 1550 nm 处，低开关功率 (P $_{\pi } $ ) 0.48 mW 获得 $450~\mu \text{m}$ 热光相互作用长度 ( $\text{L}_{\mathrm {TO}}$ ) 代表一个 $\text{P}_{\pi }\cdot \text {L} _{\mathrm {TO}}$ 仅产品 $0.22~\text {mW} \cdot \text {mm}$ ，表明热效率高，占地面积小。开关的 10% - 90% 响应时间为 $530~\mu \text{s}$ ，包括上升时间为 150 $\mu \text{s}$ ，以及下降时间 $380~\mu \text{s}$ . 与无隔离结构的开关相比，该开关的开关功率降低了17倍以上，仅需原值的5.6%。