Silicon nitride (SiN) has been well established as an ultralow-loss material for integrated photonics, particularly for the generation of dissipative Kerr soliton frequency combs, enabling various applications for optical metrology, biological imaging, and coherent telecommunications. Typically, bright soliton generation in SiN devices requires thick (>600 nm) films to fulfill the condition of anomalous dispersion at telecom wavelengths. However, thick films of ultralow-loss SiN (>400 nm) often suffer from high internal stress, leading to cracks. As an alternative approach, thin SiN films (<400 nm) provide the advantage of one-step deposition and are widely applied for commercial use. Here, we provide insights into engineering an integrated SiN structure that achieves optimal effective nonlinearity and maintains a compact footprint. A comparative analysis of SiN resonators with varying waveguide thicknesses is conducted and reveals that a 400-nm thin SiN film emerges as a promising solution that strikes a balance among the aforementioned criteria. Based on a commercially available 400-nm SiN film, we experimentally demonstrate the generation of low-noise coherent dark pulses with a repetition rate of 25 GHz in a multimode SiN resonator. The compact spiral-shaped resonator has a footprint of 0.28 mm with a high-quality factor of 4 × 10. Our demonstrated dark combs with mode spacings of tens of GHz have applications in microwave photonics, optical spectroscopy, and telecommunication systems.
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http://dx.doi.org/10.1364/OE.503637 | DOI Listing |
Nano Lett
January 2025
University Paris-Saclay, CNRS, Laboratoire de Physique des Solides, Orsay 91405, France.
Thermal transport in nanostructures plays a critical role in modern technologies. As devices shrink, techniques that can measure thermal properties at nanometer and nanosecond scales are increasingly needed to capture transient, out-of-equilibrium phenomena. We present a novel pump-probe photon-electron method within a scanning transmission electron microscope (STEM) to map temperature dynamics with unprecedented spatial and temporal resolutions.
View Article and Find Full Text PDFWe present both experimental and simulation results for a fully etched, C-band GC fabricated in an 800 nm silicon nitride platform that significantly reduces backreflections. They are minimized by truncating the initial grates, which deflect reflected light at an oblique angle and excite higher-order modes in the tapered waveguide that is filtered out. Insertion losses resulting from this modification of the grating coupler are mitigated by an adaptive redesign of the grates that corrects incurred errors in the generated phase front.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Physics, The American University in Cairo, New Cairo, 11835, Egypt.
Inverse design with topology optimization considers a promising methodology for discovering new optimized photonic structure that enables to break the limitations of the forward or the traditional design especially for the meta-structure. This work presents a high efficiency mid infra-red imaging photonics element along mid infra-red wavelengths band starts from 2 to 5 µm based on silicon nitride optimized material structures. The first two designs are broadband focusing and reflective meta-lens under very high numerical aperture condition (NA = 0.
View Article and Find Full Text PDFExtracorporeal Membrane Oxygenation (ECMO) serves as a crucial intervention for patients with severe pulmonary dysfunction by facilitating oxygenation and carbon dioxide removal. While traditional ECMO systems are effective, their large priming volumes and significant blood-contacting surface areas can lead to complications, particularly in neonates and pediatric patients. Microfluidic ECMO systems offer a promising alternative by miniaturizing the ECMO technology, reducing blood volume requirements, and minimizing device surface area to improve safety and efficiency.
View Article and Find Full Text PDFMolecules
January 2025
School of Mechanical Engineering, Chongqing Three Gorges University, Chongqing 404100, China.
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