Characterization of a high-thermal-stability spiroanthracenefluorene-based blue-light-emitting polymer optical gain medium

We report the solid-state optical gain characteristics of a spiroanthracenefluorene polymer, namely, poly(9-spiro(10,10-bis(2-ethylhexyl)-$10H$-anthracene)fluorene) (PEHSAF), specifically designed for thermal stability. An efficient stimulated emission occurs at $λ=445nm$ under amplified spontaneous emission conditions for asymmetric slab waveguide structures. The modal gain and propagation loss coefficients were found to be $g⩽38cm−1$ and $α=0.8cm−1$⁠, respectively. The PEHSAF stimulated emission characteristics are shown to be thermally stable in vacuo for temperatures up to 250 °C. Surface-emitting distributed feedback lasers have been fabricated by spin-coating PEHSAF onto one-dimensional grating structures. The lasers operate in the blue spectral region and exhibit low oscillation thresholds $(⩾18nJ)$ and relatively high slope efficiencies $(⩽5%)$⁠. Varying the PEHSAF film thickness allows the tuning of the emission wavelength within a 16 nm window.