We propose and demonstrate experimentally a 2 × 2 polymer optical waveguide thermo-optic switch, featuring wide bandwidth, low power, and weak polarization dependence. Our proposed switch is based on Mach-Zehnder interferometer (MZI) configuration and driven by a segmented graphene electrode heater formed with four identical small heaters in parallel. The use of the parallel graphene electrode heater can improve the heating efficiency by placing the heater in direct contact with the waveguide core and achieve a low driving voltage. Unlike the works reported previously, the graphene electrode heater used here achieves negligible light absorption for both the transverse electric (TE) and the transverse magnetic (TM) polarizations and, hence, weak polarization-dependent operation because a large cross-sectional square waveguide structure without upper cladding is employed. Meanwhile, two asymmetric directional couplers are employed to achieve broadband operation. Our fabricated device, which has a length of 9.5 mm, exhibits extinction ratios higher than ∼13.5 dB over a wavelength range of 1530 – 1605 nm and higher than ∼26 dB at 1561 nm for all channels. The switching powers are ∼3.30 and 3.12 mW for the TE and TM polarizations, respectively. The insertion losses are lower than 10.5 dB for all channels. The rise and fall time of switching are 0.98 and 0.52 ms, respectively.

中文翻译：

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使用分段石墨烯加热器的具有弱偏振依赖性的低功率宽带热光开关

我们提出并实验证明了一种 2 × 2 聚合物光波导热光开关，具有宽带宽、低功率和弱偏振依赖性。我们提出的开关基于 Mach-Zehnder 干涉仪 (MZI) 配置，并由由四个相同的并联小加热器组成的分段石墨烯电极加热器驱动。使用并联石墨烯电极加热器可以通过将加热器与波导芯直接接触来提高加热效率并实现低驱动电压。与之前报道的工作不同，这里使用的石墨烯电极加热器对横向电 (TE) 和横向磁 (TM) 极化的光吸收都可以忽略不计，因此，由于采用了没有上包层的大横截面方形波导结构，因此与偏振相关的操作很弱。同时，采用两个非对称定向耦合器来实现宽带操作。我们制造的器件长度为 9.5 mm，在 1530 – 1605 nm 的波长范围内显示出高于 ~13.5 dB 的消光比，在 1561 nm 处所有通道的消光率高于 ~26 dB。TE 和 TM 极化的开关功率分别为~3.30 和 3.12 mW。所有通道的插入损耗均低于 10.5 dB。开关的上升和下降时间分别为 0.98 和 0.52 ms。在 1530 – 1605 nm 的波长范围内为 5 dB，对于所有通道在 1561 nm 处高于 ~26 dB。TE 和 TM 极化的开关功率分别为~3.30 和 3.12 mW。所有通道的插入损耗均低于 10.5 dB。开关的上升和下降时间分别为 0.98 和 0.52 ms。在 1530 – 1605 nm 的波长范围内为 5 dB，对于所有信道在 1561 nm 处高于 ~26 dB。TE 和 TM 极化的开关功率分别为~3.30 和 3.12 mW。所有通道的插入损耗均低于 10.5 dB。开关的上升和下降时间分别为 0.98 和 0.52 ms。