Different　distributed　feedback　(DFB)　configurations　in　optically　pumped　polymer　lasers,　including　the　active　Bragg　grating　structures,　the　dielectric　grating　structures　spin-coated　with　polymeric　semiconductors,　and　the　actively　waveguide　dielectric　grating　structures　(AWGS),　are　studied　systematically.　In　the　experiment,　the　F8BT　polymer　poly　[(9,9-　dioctylfluorenyl-2,7-diyl)-alt-co-　(1,4-benzo-{2,1＇,3}　-thiadiazole)]　is　employed　as　the　active　medium　in　the　three　laser　configuration.　And　all　grating　structures　are　fabricated　though　interference　lithography　or　interference　ablation.　It　is　found　that　the　AWGS　design　has　advantages　over　the　other　two.　The　continuous　and　high-quality　active　waveguide　in　the　AWGS　enables　low-threshold　(115　μJ/cm2)　laser　emission　with　narrow　linewidth　(~0.4　nm　at　full-width　at　half-maximum).　The　experimental　verifications　are　in　good　agreement　with　the　theoretical　analysis.　These　results　reveal　some　interesting　mechanisms　in　optically　pumped　DFB　polymer　lasers,　and　it　may　be　enlightening　to　the　construction　of　electrically　driven　organic　lasers.　©　2012　Chinese　Optics　Letter.