Abstract
We introduce shape-memory polymers (SMP) as substrate material for active optical devices. As an exemplary application we build a tunable organic semiconductor distributed feedback (DFB) laser. Hence, we transfer a second order Bragg grating with a period of 400 nm into SMP foils by hot embossing. The composite organic gain medium Alq3:DCM evaporated on the SMP substrate serves as laser active material. Mechanical stretching of the substrate increases the grating period temporarily and triggering the shape-memory effect afterwards reduces the period on demand. In this way, we can adjust the grating period to achieve a broad continuously tuning of the laser emission wavelength by 30 nm.
Highlights
Smart polymers and applications thereof received rising attention during the last decade. [1,2,3,4,5,6,7]
We describe the basic features of the shape-memory polymers (SMP) grating structure and analyze the properties of a continuously tunable distributed feedback (DFB) laser build with this component
Since we tune the DFB laser by modifying the resonator’s period, the evaporated organic Alq3:DCM layer may be mechanically deformed by the pre-stretching of the substrate for the programming of the temporary shape as well as during the recovery process
Summary
Smart polymers and applications thereof received rising attention during the last decade. [1,2,3,4,5,6,7]. For the fabrication of rigid chirped gratings, time-consuming lithography is needed for every substrate [24, 26] while state-of-the-art rubber-like grating substrates depend on complex rigid set-ups for adjustment [18, 26] or elaborate mechanical supports [19,20,21,22, 24, 25, 27, 28] These constraints are avoided with gratings made out of SMPs. Here, we demonstrate an organic DFB laser featuring a mechanically pre-stretched SMP substrate with a surface Bragg grating as resonator structure. We describe the basic features of the SMP grating structure and analyze the properties of a continuously tunable DFB laser build with this component
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