Completely polarized photoluminescence emission from a microcavity containing an aligned conjugated polymer

We present a study of 1-D optical microcavities based on a dielectric mirro r, a layer of an aligned fluorescent conjugated polymer (poly(9,9-dioctylfl uorene) (PFO)) and a metallic mirror. The aligned polymer film is birefring ent, with a refractive index difference calculated to be 0.36 between direc tions parallel and perpendicular to the alignment direction. Because of the large birefringence, two cavity modes are observed within the microcavity stop band. They are split by 32 nm and are polarized parallel and perpendic ular to the alignment direction. Photoluminescence from the PFO film corres pondingly shows two emission bands with mutually perpendicular polarization s. The polarization ratio of the most intense mode exceeds 300:1. We discus s how this structure might be used to construct highly polarized light-sour ces. (C) 2001 Elsevier Science B.V. All rights reserved.