Relationship between photonic band structure and emission characteristics of a polymer distributed feedback laser

TLDR

The second‑order distributed feedback mechanism yields a distinct photonic band structure, as shown by the measured band gap. We experimentally investigate the emission characteristics and photonic band structure of a polymer distributed feedback laser made from poly[2‑methyl‑5‑(2‑ethylhexyloxy)-1,4‑phenylene vinylene]. By measuring the photonic band dispersion, we explain how substrate microstructure alters both spontaneous and stimulated emission. The laser exhibits a one‑dimensional photonic band gap centered at 610 nm, with lasing occurring at one of the two band edges, selected by differing output coupling of the modes at those edges.

Abstract

We present an experimental study of the emission characteristics and photonic band structure of a distributed feedback polymer laser, based on the material poly[${2\ensuremath{-}\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{h}\mathrm{o}\mathrm{x}\mathrm{y}\ensuremath{-}5\ensuremath{-}(2}^{\ensuremath{'}}$-ethylhexyloxy)-1,4-phenylene vinylene]. We use measurements of the photonic band dispersion to explain how the substrate microstructure modifies both spontaneous and stimulated emission. The lasing structure exhibits a one-dimensional photonic band gap around 610 nm, with lasing occurring at one of the two associated band edges. The band edge (frequency) selection mechanism is found to be a difference in the level of output coupling of the modes associated with the two band edges. This is a feature of the second-order distributed feedback mechanism we have employed and is clearly evident in the measured photonic band structure.