Photopumped cylindrical polymer microcavities produce laser emission at about 630 nm

Photopumped cylindrical polymer microcavities produce laser emission at about 630 nm

Low threshold current is a key to fabricating laser diodes from light-emitting polymers. Because cylindrical microcavities provide superior two-dimensional optical confinement for semiconductor lasers, researchers from the University of Utah (Salt Lake City, UT) and Osaka University (Osaka, Japan) have applied this design to optimize photopumped polymer lasers. Using a self-assembly technique, the grou¥formed ring microcavities by coating optical fibers ranging from 5 to 200 µm in diameter with about 1 µm of 2,5-dioctyloxy poly(p-phenylene-vinylene) (DOO-PPV), which is an excellent laser-active medium at red/yellow wavelengths. A frequency-doubled Nd:YAG laser pumped one side of the polymer ring at 532 nm, while the polymer emission was collected on the other side and analyzed by a 0.6-m spectrometer and a CCD camera. Laser emission wavelengths were close to the maximum of the polymer`s optical gain spectrum (630 nm). Lasing also was observed when DOO-PPV film was deposited around an aluminum wire, opening u¥the possibility of electrical pumping when polymer quality is improved.