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Fabrication of height modulated and tapered features in fused silica

This LLNL invention allows for the fabrication of complex waveplate features and topologies from fused silica, a highly desirable and durable waveplate material.  It also is a unique technique for density multiplication and high-fidelity bidirectional deposition, which can create optical components that are generally for entirely new classes of optical materials.

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Standing in LLNL’s Center for Micro Nano Technology, Nathan Ray holds a marvel of optical engineering, a 5-centimeter metasurface optic

This LLNL invention concerns a method for patterning the index of refraction by fabricating a spatially invariant metasurface, and then apply spatially varied mechanical loading to compress the metasurface features vertically and spread them radially. In doing so, the index of refraction can be re-written on the metasurface, thus enabling index patterning. This process allows rapid 'rewriting…

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SEM image of etched metasurface with angled features

This novel invention specifically enables the fabrication of arbitrarily tailored birefringence characteristics in nano-structured meta-surfaces on non-birefringent substrates (e.g. fused silica). The birefringent nano-structured meta-surface is produced by angled directional reactive ion beam etching through a nano-particle mask. This method enables the simultaneous tailoring of refractive…

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Schematic of one methodology for achieving a thicker substrate engraved meta-surface (SEMS) layer

This invention (US Patent No. 11,294,103) is an extension of another LLNL invention, US Patent No. 10,612,145, which utilizes a thin sacrificial metal mask layer deposited on a dielectric substrate (e.g. fused silica) and subsequently nanostructured through a laser generated selective thermal de-wetting process.

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Adobe Stock image laser beam

This invention proposes to engineer the current density along the length of a laser diode to overcome the penalty associated with non-uniformity resulting from asymmetry in the gain, photon or carrier density despite having uniform contact. Optimizing the current density profile enables diode lasers to operate with greater power conversion efficiency or operate with equivalent power conversion…

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Schematic showing mismatched coefficient of thermal expansion (CTE) coating

This invention proposes to engineer the temperature dependence of the emission wavelength of LEDs and laser diodes. The approach is to use a strain-inducing coating to counteract the intrinsic temperature coefficient of the emission wavelength of the LED or laser diode device thereby rendering it athermal. This invention avoids additional complexity, size, weight and power dissipation of…

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Photoconductive Semiconductor Laser Diodes and LEDs

This invention proposes a method to overcome the key limitation of electrically pumped lasers based on AlN, AlGaN, or AlInGaN, namely the lack of suitable shallow donor and acceptor dopants. As the band gap of these materials increases (and the emission wavelength decreases), both electrons and holes require greater thermal energies in order to ionize.

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Adobe Stock image laser beam

Laser diode lensing effect can be substantially reduced by creating a pattern interface such that the substrate is only attached at the diode mesa. This is achieved by either creating a pattern solder joint and/or pattern substrate.

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Scanning electron micrograph of scalable, grating-like nanoscale metal mask (line period ~35 nm)

This invention consists of a method of forming nanoscale metal lines to produce a grating-like mask with wide area coverage over the surface of a durable optical material such as fused silica. Subsequent etching processes transfer the metal mask to the underlying substrate forming a birefringent metasurface. This method enables the production of ultrathin waveplates for high power laser…

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Scanning electron micrograph of bulk metamaterial structures fabricated at LLNL

Heat sensitive materials such as piezoelectric and MEMS devices and assemblies, magnetic sensors, nonlinear optical crystals, laser glass or solid-state laser materials, etc. cannot be exposed to excess temperatures which in the context of this invention, means materials that cannot be exposed to temperatures greater than 50°C (122°F). LLNL’s invention describes a low-temperature method of…

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Linearly polarized light entering a half-wave plate can be resolved into two waves, parallel and perpendicular to the optic axis of the waveplate ("Waveplate" by Bob Mellish is licensed under CC BY-SA 3.0).

This novel method of producing waveplates from isotropic optical materials (e.g. fused silica) consists of forming a void-dash metasurface using the following process steps: