An official website of the United States government
A versatile system for the fabrication of surface microstructures is demonstrated by combining the photomechanical response of supramolecular azopolymers with structured polarized illumination from a high resolution spatial light modulator. Surface relief structures with periods 900 nm - 16.5 µm and amplitudes up to 1.0 µm can be fabricated with a single 5 sec exposure at 488 nm. Sinusoidal, circular, and chirped surface profiles can be fabricated via direct programming of the spatial light modulator, with no optomechanical realignment required. Surface microstructures can be combined into macroscopic areas by mechanical translation followed by exposure. The surface structures grow immediately in response to illumination, can be visually observed in real time, and require no post-exposure processing.
more »
« less
Supramolecular Azopolymers for Dynamic Surface Microstructures Using Digital Polarization Optics
Abstract Thin film supramolecular azopolymers support the all‐optical generation of dynamic surface microstructures. Using a spatial light modulator (SLM) illuminated at 488 nm, structured polarized light drives surface waves of sinusoidal profile with periods 700 nm–5 µm at speeds up to 1 µm s−1. Multiple regions on the film surface within the SLM focal plane can be independently set into motion, each with unique period, speed, amplitude, and propagation direction. The underlying mechanism is the photomechanical response of the azopolymer, which is more commonly exploited for the fabrication of static surface microstructures. Hydrogen‐bonded systems such as the supramolecular system described here are particularly advantageous due to their facile fabrication from commercially available components. In addition to applications in dynamic diffractive optics, this programmable system for optical surface waves is well‐suited for studies in nanoparticle manipulation, as well as in bioengineering as a reconfigurable surface template for directed cell growth.
more »
« less
- PAR ID:
- 10400933
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 11
- Issue:
- 8
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
A maskless single beam process for photofabrication of surface microstructures is reported. A continuously moving azopolymer film is illuminated with structured polarized light from a 488 nm laser and spatial light modulator, driving the formation of surface relief gratings in real time. The structures were replicated using nanoimprint lithography, and exhibited a maximum diffraction efficiency of order 30% at 633 nm. Using the period tunability of the spatial light modulator, surface gratings were fabricated that diffract red, green, and blue light along a common direction, illustrating the potential of this fabrication platform in the field of structured color.more » « less
-
Nanostructured materials and nanolattices with high porosity can have novel optical and mechanical properties that are attractive for nanophotonic devices. One existing challenge is the integration of microstructures that can be used as waveguides or electrodes on such nanostructures without filling in the pores. This study investigates the fabrication of TiO2 microstructures on nanolattices using a stencil mask. In this approach, the nanostructures are planarized with a polymer film while the microstructures are patterned in a sequential shadow deposition step. Our results demonstrate the successful fabrication of a “dog-bone” microstructure with 400 μm length, 100 μm width, and 30–560 nm thicknesses on nanostructure with 390 and 500 nm period. The experimental results show that cracks can form in the microstructures, which can be attributed to residual stress and the thermal annealing cycle. A key finding is that the film cracks decrease as the TiO2 layer becomes thinner, highlighting an important relationship between grain size distribution and the film thickness. The mechanical stability of the underlying nanolattices also plays a key role, where interconnected architecture mitigated the crack formation when compared with isolated structures. The demonstrated fabrication process can lead to integrated waveguides and microelectrodes on nanolattices, which can find applications for next-generation photonic and electronic devices.more » « less
-
Abstract Polycrystalline yttrium aluminum garnet (YAG) ceramic doped with neodymium (Nd), referred to as Nd:YAG, is widely used in solid‐state lasers. However, conventional powder metallurgy methods suffer from expenses, time consumption, and limitations in customizing structures. This study introduces a novel approach for creating Nd:YAG ceramics with 3D free‐form structures from micron (∼70 µm) to centimeter scales. Firstly, sol‐gel synthesis is employed to form photocurable colloidal solutions. Subsequently, by utilizing a home‐built micro‐continuous liquid interface printing process, precursors are printed into 3D poly(acrylic acid) hydrogels containing yttrium, aluminum, and neodymium hydroxides, with a resolution of 5.8 µmpixel−1at a speed of 10 µm s−1. After the hydrogels undergo thermal dehydration, debinding, and sintering, polycrystalline Nd:YAG ceramics featuring distinguishable grains are successfully produced. By optimizing the concentrations of the sintering aids (tetraethyl orthosilicate) and neodymium trichloride (NdCl3), the resultant samples exhibit satisfactory photoluminescence, emitting light concentrated at 1064 nm when stimulated by a 532 nm laser. Additionally, Nd:YAG ceramics with various 3D geometries (e.g., cone, spiral, and angled pillar) are printed and characterized, which demonstrates the potential for applications, such as laser and amplifier fibers, couplers, and splitters in optical circuits, as well as gain metamaterials or metasurfaces.more » « less
-
We demonstrate a thermoreflectance-based thermometry technique with an ultimate temperature resolution of 60 µK in a 2.6 mHz bandwidth. This temperature resolution was achieved using a 532 nm-wavelength probe laser and a ∼1 µm-thick silicon transducer film with a thermoreflectance coefficient of −4.7 × 10−3 K−1at room temperature. The thermoreflectance sensitivity reported here is over an order-of-magnitude greater than that of metal transducers, and is comparable to the sensitivity of traditional resistance thermometers. Supporting calculations reveal that the enhancement in sensitivity is due to optical interference in the thin film.more » « less
