Fast photothermal spatial light modulation for quantitative phase imaging at the nanoscale

Abstract

Spatial light modulators have become an essential tool for advanced microscopy, enabling breakthroughs in 3D, phase, and super-resolution imaging. However, continuous spatial-light modulation that is capable of capturing sub-millisecond microscopic motion without diffraction artifacts and polarization dependence is challenging. Here we present a photothermal spatial light modulator (PT-SLM) enabling fast phase imaging for nanoscopic 3D reconstruction. The PT-SLM can generate a step-like wavefront change, free of diffraction artifacts, with a high transmittance and a modulation efficiency independent of light polarization. We achieve a phase-shift > π and a response time as short as 70 µs with a theoretical limit in the sub microsecond range. We used the PT-SLM to perform quantitative phase imaging of sub-diffractional species to decipher the 3D nanoscopic displacement of microtubules and study the trajectory of a diffusive microtubule-associated protein, providing insights into the mechanism of protein navigation through a complex microtubule network.

Optical Metasurfaces for Energy Conversion

“…Faster response times can be obtained by reducing the size of the heat-generating metallic circuit. 451 Recently, optimization of the thermal properties of a multilayer stack allowed the realization of a SLM based on the thermo-optic effect with a rise time of only 70 μs, 452 two orders of magnitude faster than conventional SLMs. While in this implementation, the temperature increase was provided by randomly assembled gold nanorods, one can envision to improve the thermal SLM design by leveraging the control over the heating profile that can be obtained with a carefully designed plasmonic metasurface.…”

Scattering-based Light Microscopy: From Metal Nanoparticles to Single Proteins

“…34 Recent developments in the Piliarik group expanded the general principle of introducing a spatial filter beyond static field attenuation or phase retardation. 169 Replacing the thin metal film disk with a layer of GNRs, the purpose of the spatial filter was not solely to attenuate the reference field but also to change its phase. By sandwiching a layer of thermo-optic material, namely liquid glycerol, between the gold-coated glass substrate and a sapphire heat sink (Figure 10E), the local refractive index of the glycerol can be rapidly altered by microscopic heating (Figure 10F), which in turn results in a phase retardation of the transmitted optical wave (Figure 10G).…”

“…Copyright 2017 American Chemical Society. (E–I) Adapted with permission from ref . Copyright 2021 Springer Nature under Creative Commons Attribution 4.0 International License .…”

“…Recent developments in the Piliarik group expanded the general principle of introducing a spatial filter beyond static field attenuation or phase retardation . Replacing the thin metal film disk with a layer of GNRs, the purpose of the spatial filter was not solely to attenuate the reference field but also to change its phase.…”

Shaping of Optical Wavefronts Using Light‐Patterned Photothermal Metamaterial

“…To overcome the limitation of long-range heat crosstalk, we recently demonstrated the possibility of rapid (70 µs) and sensitive phase-shift adjustment using a specialized photothermal SLM (PT-SLM), addressing a specific spatially confined region of the beam cross-section without influencing the imaging information transmitted outside of this modulated region. [26] Here, we introduce the concept of arbitrary wavefront shaping combining the advantages of smooth and continuous wavefront adjustments free of diffraction artifacts with the possibility of generating rapid phase jumps. The generation of the 2D phase pattern is fully optically addressable and with minimized lateral crosstalk.…”