Publications by authors named "D A Czaplewski"
Article Synopsis
- Optical metasurfaces can control electromagnetic waves at very thin surfaces, specifically in the mid-infrared (mid-IR) region, enhancing applications like biochemical sensing and spectroscopy.
- Current mid-IR metasurfaces are often made on substrates that reduce performance and complicate access to important electromagnetic hotspots, while alternative IR-transparent materials can be problematic or costly.
- This study introduces new free-standing silicon (Si) membrane metasurfaces that improve light trapping and resonance quality, enabling scalable production and advanced applications in fields like quantum mechanics and biochemical sensing.
Integrating phase-change materials in metasurfaces has emerged as a powerful strategy to realize optical devices with tunable electromagnetic responses. Here, phase-change chiral metasurfaces based on GST-225 material with the designed trapezoid-shaped resonators are demonstrated to achieve tunable circular dichroism (CD) responses in the infrared regime. The asymmetric trapezoid-shaped resonators are designed to support two chiral plasmonic resonances with opposite CD responses for realizing switchable CD between negative and positive values using the GST phase change from amorphous to crystalline.
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- Photoacoustic computed tomography (PACT) uses diffusive laser excitation and photoacoustic signal detection, making it effective for deep tissue imaging with improved spatial resolution when using ultrasound point detectors.
- Micro-ring resonator (MRR) based ultrasound detectors stand out for their low area-normalized limit of detection (nLOD) and miniature size, although the signal transduction process hasn't been thoroughly researched yet.
- A new theoretical model has been developed to quantify the signal-to-noise ratio (SNR) and nLOD based on key parameters, achieving accurate predictions that align with experimental data, thus guiding enhancements in ultrasound detection for better imaging quality.
Optical phase-change materials exhibit tunable permittivity and switching properties during phase transition, which offers the possibility of dynamic control of optical devices. Here, a wavelength-tunable infrared chiral metasurface integrated with phase-change material GST-225 is demonstrated with the designed unit cell of parallelogram-shaped resonator. By varying the baking time at a temperature above the phase transition temperature of GST-225, the resonance wavelength of the chiral metasurface is tuned in the wavelength range of 2.
View Article and Find Full Text PDF3D photoacoustic computed tomography (3D-PACT) has made great advances in volumetric imaging of biological tissues, with high spatial-temporal resolutions and large penetration depth. The development of 3D-PACT requires high-performance acoustic sensors with a small size, large detection bandwidth, and high sensitivity. In this work, we present a new high-frequency 3D-PACT system that uses a micro-ring resonator (MRR) as the acoustic sensor.
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