title: Tunable Diffractive Optical Elements Based on Shape-Memory Polymers Fabricated via Hot Embossing.
abstract: We introduce actively tunable diffractive optical elements fabricated from shape-memory polymers (SMPs). By utilizing the shape-memory effect of the polymer, at least one crucial attribute of the diffractive optical element (DOE) is tunable and adjustable subsequent to the completed fabrication process. A thermoplastic, transparent, thermoresponsive polyurethane SMP was structured with diverse diffractive microstructures via hot embossing. The tunability was enabled by programming a second, temporary shape into the diffractive optical element by mechanical deformation, either by stretching or a second embossing cycle at low temperatures. Upon exposure to the stimulus heat, the structures change continuously and controllable in a predefined way. We establish the novel concept of shape-memory diffractive optical elements by illustrating their capabilities, with regard to tunability, by displaying the morphing diffractive pattern of a height tunable and a period tunable structure, respectively. A sample where an arbitrary structure is transformed to a second, disparate one is illustrated as well. To prove the applicability of our tunable shape-memory diffractive optical elements, we verified their long-term stability and demonstrated the precise adjustability with a detailed analysis of the recovery dynamics, in terms of temperature dependence and spatially resolved, time-dependent recovery.
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Senta
authors.initials: S
authors.lastname: Schauer
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Meier
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reinhard
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Röhrig
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schneider
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Heilig
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kolew
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Worgull
authors.affiliation: Institute of Microstructure Technology, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Hölscher
keywords: diffractive optical elements; hot embossing; recovery dynamics; shape-memory polymer; spatially resolved recovery; tunable microoptics