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Abstract Nonvolatile photonic integrated circuits employing phase change materials have relied either on optical switching mechanisms with precise multi-level control but poor scalability or electrical switching with seamless integration and scalability but mostly limited to a binary response. Recent works have demonstrated electrical multi-level switching; however, they relied on the stochastic nucleation process to achieve partial crystallization with low demonstrated repeatability and cyclability. Here, we re-engineer waveguide-integrated microheaters to achieve precise spatial control of the temperature profile (i.e., hotspot) and, thus, switch deterministic areas of an embedded phase change material cell. We experimentally demonstrate this concept using a variety of foundry-processed doped-silicon microheaters on a silicon-on-insulator platform to trigger multi-step amorphization and reversible switching of Sb₂Se₃and Ge₂Sb₂Se₄Te alloys. We further characterize the response of our microheaters using Transient Thermoreflectance Imaging. Our approach combines the deterministic control resulting from a spatially resolved glassy-crystalline distribution with the scalability of electro-thermal switching devices, thus paving the way to reliable multi-level switching towards robust reprogrammable phase-change photonic devices for analog processing and computing. 

Programmable and reconfigurable optics hold significant potential for transforming a broad spectrum of applications, spanning space explorations to biomedical imaging, gas sensing, and optical cloaking. The ability to adjust the optical properties of components like filters, lenses, and beam steering devices could result in dramatic reductions in size, weight, and power consumption in future optoelectronic devices. Among the potential candidates for reconfigurable optics, chalcogenide‐based phase change materials (PCMs) offer great promise due to their non‐volatile and analogue switching characteristics. Although PCM have found widespread use in electronic data storage, these memory devices are deeply sub‐micron‐sized. To incorporate phase change materials into free‐space optical components, it is essential to scale them up to beyond several hundreds of microns while maintaining reliable switching characteristics. This study demonstrated a non‐mechanical, non‐volatile transmissive filter based on low‐loss PCMs with a 200 × 200 µm²switching area. The device/metafilter can be consistently switched between low‐ and high‐transmission states using electrical pulses with a switching contrast ratio of 5.5 dB. The device was reversibly switched for 1250 cycles before accelerated degradation took place. The work represents an important step toward realizing free‐space reconfigurable optics based on PCMs. 

We experimentally demonstrate the first electrically programmable, non-volatile silicon photonic content addressable memory cell using Sb₂Se₃phase change material on microring resonators, opening the path for light-based search operations in zero-power look-up tables. 

Reconfigurable or programmable photonic devices are rapidly growing and have become an integral part of many optical systems. The ability to selectively modulate electromagnetic waves through electrical stimuli is crucial in the advancement of a variety of applications from data communication and computing devices to environmental science and space explorations. Chalcogenide‐based phase‐change materials (PCMs) are one of the most promising material candidates for reconfigurable photonics due to their large optical contrast between their different solid‐state structural phases. Although significant efforts have been devoted to accurate simulation of PCM‐based devices, in this paper, three important aspects which have often evaded prior models yet having significant impacts on the thermal and phase transition behavior of these devices are highlighted: the enthalpy of fusion, the heat capacity change upon glass transition, as well as the thermal conductivity of liquid‐phase PCMs. The important topic of switching energy scaling in PCM devices, which also helps explain why the three above‐mentioned effects have long been overlooked in electronic PCM memories but only become important in photonics, is further investigated. These findings offer insight to facilitate accurate modeling of PCM‐based photonic devices and can inform the development of more efficient reconfigurable optics. 

Electrically tunable optical devices present diverse functionalities for manipulating electromagnetic waves by leveraging elements capable of reversibly switching between different optical states. This adaptability in adjusting their responses to electromagnetic waves after fabrication is crucial for developing more efficient and compact optical systems for a broad range of applications, including sensing, imaging, telecommunications, and data storage. Chalcogenide‐based phase‐change materials (PCMs) have shown great promise due to their stable, nonvolatile phase transition between amorphous and crystalline states. Nonetheless, optimizing the switching parameters of PCM devices and maintaining their stable operation over thousands of cycles with minimal variation can be challenging. Herein, the critical role of PCM pattern as well as electrical pulse form in achieving reliable and stable switching is reported on, extending the operational lifetime of the device beyond 13000 switching events. To achieve this, a computer‐aided algorithm that monitors optical changes in the device and adjusts the applied voltage in accordance with the phase transformation process is developed, thereby significantly enhancing the lifetime of these reconfigurable devices. The findings reveal that patterned PCM structures show significantly higher endurance compared to blanket PCM thin films. 

Owing to their unique tunable optical properties, chalcogenide phase change materials are increasingly being investigated for optics and photonics applications. However, in situ characterization of their phase transition characteristics is a capability that remains inaccessible to many researchers. Herein, a multifunctional silicon microheater platform capable of in situ measurement of structural, kinetic, optical, and thermal properties of these materials is introduced. The platform can be fabricated leveraging industry‐standard silicon foundry manufacturing processes. This platform is fully open‐sourced, including complete hardware design and associated software codes.