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Temperature profile and transient response of thermally tunable ridge waveguides with laterally supported suspension
摘要： Using the thermoreflectance imaging method, the temperature profile and transient response of thermally tunable ridge waveguides with laterally supported suspension are investigated. This method has a high accuracy in the temperature measurement. The experimental data convincingly confirm a uniform temperature distribution along the waveguide except the initial 30 μm long sections near the two longitudinal edges. The 10%–90% rising time and 90%–10% falling time of the device transient thermal response are also measured to be ≈48 μs and ≈44 μs, respectively, regardless of different waveguide lengths and at different heating powers. In addition, the delay time of the waveguide transient thermal response is revealed to be 1.3 μs by comparison between experiment and simulation.
关键词： thermally tunable ridge waveguides,thermoreflectance imaging,temperature profile,transient response
更新于2025-09-19 17:13:59
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Current Localization and Redistribution as the Basis of Discontinuous Current Controlled Negative Differential Resistance in NbO <i> <sub/>x</sub></i>
摘要： Devices exploiting negative differential resistance (NDR) are of particular interest for analog computing applications, including oscillator-based neural networks. These devices typically exploit the continuous S-shaped current–voltage characteristic produced by materials with a strong temperature-dependent electrical conductivity, but recent studies have also highlighted the existence of a second, discontinuous (snap-back) characteristic that has the potential to provide additional functionality. The development of devices based on this characteristic is currently limited by uncertainty over the underlying physical mechanism, which remains the subject of active debate. In situ thermoreflectance imaging and a simple model are used to finally resolve this issue. Specifically, it is shown that the snap-back response is a direct consequence of current localization and redistribution within the oxide film, and that material and device dependencies are consistent with model predictions. These results conclusively demonstrate that the snap-back characteristic is a generic response of materials with a strong temperature-dependent conductivity and therefore has the same physical origin as the S-type characteristic. This is a significant outcome that resolves a long-standing controversy and provides a solid foundation for engineering functional devices with specific NDR characteristics.
关键词： brain-inspired computing,negative differential resistance,niobium oxide,thermoreflectance imaging,transition metal oxides
更新于2025-09-11 14:15:04