More Like this

1. Functional Metamaterial Devices Enabled by Microsystems

   https://doi.org/10.1109/IEDM13553.2020.9371924  

   Zhang, X.; Zhao, X. (December 2020, 2020 IEEE International Electron Devices Meeting (IEDM))

   null (Ed.)

   Metamaterials represent a class of artificially engineered materials, which exhibit unprecedented properties enabled by their constituent subwavelength unit cells. The effective properties of metamaterials may be dynamically controlled by driving unit cells via different approaches, including photo-doping, electrical gating, or mechanical actuation. With such dynamical tuning mechanisms, the propagation modality of electromagnetic waves may be modulated to achieve functional devices for modulation, beam steering, focusing, and polarization control, among others. In addition, the perfect absorption and near field effect enabled by metamaterials may be used in electromagnetic detectors across the frequency spectrum. Microsystem technology provides a platform to achieve functional metamaterial devices by covering all requisite processes, including fabrication, packaging, and system integration. We report our progress in constructing functional devices by integrating metamaterials with microsystems technology and discuss remaining challenges and the future direction of metamaterial devices. 

   more » « less
2. Design and characterization of a 60-cm reflective half-wave plate for the CLASS 90 GHz band telescope

   https://doi.org/10.1117/12.3016346  

   Shi, Rui; Brewer, Michael; Chan, Carol; Chuss, David T; Couto, Jullianna D; Eimer, Joseph R; Karakla, John; Shukawa, Koji; Valle, Deniz; Appel, John W; et al (August 2024, SPIE)

   Zmuidzinas, Jonas; Gao, Jian-Rong (Ed.)

   Front-end polarization modulation enables improved polarization measurement stability by modulating the targeted signal above the low-frequency $1/f$ drifts associated with atmospheric and instrumental instabilities and diminishes the impact of instrumental polarization. In this work, we present the design and characterization of a new 60-cm diameter Reflective Half-Wave Plate (RHWP) polarization modulator for the 90 GHz band telescope of the Cosmology Large Angular Scale Surveyor (CLASS) project. The RHWP consists of an array of parallel wires (diameter 50~µm, 175~µm pitch) positioned 0.88~mm from an aluminum mirror. In lab tests, it was confirmed that the wire resonance frequency ($$f_\mathrm{res}$$) profile is consistent with the target, $139$~Hz$$<154$$~Hz in the optically active region (diameter smaller than 150~mm), preventing the wire vibration during operation and reducing the RHWP deformation under the wire tension. The mirror tilt relative to the rotating axis was controlled to be $<15''$, corresponding to an increase in beam width due to beam smearing of < $0.6''$, %a beam smearing amplitude of $<0.6''$, negligible compared to the beam's full-width half-maximum of $36'$. The median and 16/84th percentile of the wire--mirror separation residual was $$0.048^{+0.013}_{-0.014}$$~mm in the optically active region, achieving a modulation efficiency $$\epsilon=96.2_{+0.5}^{-0.4}\%$$ with an estimated bandpass of 34~GHz. The angular velocity of the RHWP was maintained to an accuracy of within 0.005\% at the nominal rotation frequency (2.5~Hz). The RHWP has been successfully integrated into the CLASS 90 GHz telescope and started taking data in June 2024, replacing the previous modulator that has been in operation since June 2018. 

   more » « less
3. Acceleration and focusing of multispecies ion beam using a converging laser-driven shock

   https://doi.org/10.1103/PhysRevE.111.025203  

   Kim, Jihoon; Rajawat, Roopendra; Wang, Tianhong; Shvets, Gennady (February 2025, Physical Review E)

   We demonstrate an ion acceleration scheme capable of simultaneously focusing and accelerating a multi- species ion beam with monoenergetic spectra to a few micron radius. The focal length and ion mean energy can be independently controlled: the former by using a different front-surface shape and the latter by tuning the laser- plasma parameters. We interpret the results using simple models and validate the results using first-principles simulations. The scheme is applicable to different laser transverse profiles and multi-ion species targets, and limiting factors for the ion focusing are delineated. The generated ion beam exhibits high charge, low emittance, and high-energy flux and is of interest for various applications, including inertial confinement fusion, high-flux neutron generation, and biomedical applications. 

   more » « less
4. Single-pulse, reference-free, spatiospectral measurement of ultrashort pulse-beams

   https://doi.org/10.1364/OPTICA.462586  

   Goldberger, David; Barolak, Jonathan; Bevis, Charles S; Ivanic, Bojana; Schmidt, David; Lei, Yuhao; Kazansky, Peter; Mancini, Giulia F; Durfee, Charles G; Adams, Daniel E (January 2022, Optica)

   High-intensity pulse-beams are ubiquitous in scientific investigations and industrial applications ranging from the generation of secondary radiation sources (e.g., high harmonic generation, electrons) to material processing (e.g., micromachining, laser-eye surgery). Crucially, pulse-beams can only be controlled to the degree to which they are characterized, necessitating sophisticated measurement techniques. We present a reference-free, full-field, single-shot spatiospectral measurement technique called broadband single-shot ptychography (BBSSP). BBSSP provides the complex wavefront for each spectral and polarization component in an ultrafast pulse-beam and should be applicable across the electromagnetic spectrum. BBSSP will dramatically improve the application and mitigation of spatiospectral pulse-beam structure. 

   more » « less
5. High spatial precision nano-imaging of polarization-sensitive plasmonic particles

   https://doi.org/10.1117/12.2289143  

   Liu, Yunbo; Wang, Yipei; Lee, Somin E (February 2018, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XV)

   Precise polarimetric imaging of polarization-sensitive nanoparticles is essential for resolving their accurate spatial positions beyond the diffraction limit. However, conventional technologies currently suffer from beam deviation errors which cannot be corrected beyond the diffraction limit. To overcome this issue, we experimentally demonstrate a spatially stable nano-imaging system for polarization-sensitive nanoparticles. In this study, we show that by integrating a voltage-tunable imaging variable polarizer with optical microscopy, we are able to suppress beam deviation errors. We expect that this nano-imaging system should allow for acquisition of accurate positional and polarization information from individual nanoparticles in applications where real-time, high precision spatial information is required. 

   more » « less