Low threshold distributed feedback lasers fabricated from blends of conjugated polymers: Reduced losses through Förster transfer

We report on low threshold photopumped amplified spontaneous emission (ASE) in blends of derivatives of poly (p-phenylene vinylene) and distributed feedback (DFB) lasers fabricated from the same materials. Frster energy transfer is used to spectrally shift the emission away from the absorption band, thereby reducing the optical losses. The concentration of the guest polymer in the blend determines the rate of energy transfer and, thereby, has a strong effect on the observed emission spectrum. The photoluminescence quantum efficiencies (ηPL) of the blends are higher than the ηPL of the pure emissive species (ηPL decreases with increasing amount of the guest polymer in the blends). The blends exhibit optical losses ∼3cm-1 compared to ∼85cm-1 in pure host. As a result, the ASE thresholds are reduced from 5000W/cm2 in the host to 200W/cm2 in the blends. The corresponding lasing threshold in the DFB structures is 100W/cm2. © 2002 American Institute of Physics.