Abstract
We report a study of light amplification in dilute solutions of the semiconducting polymer poly(9,9-dioctylfluorene-
co
-benzothiadiazole) (F8BT). The operating characteristics of the F8BT solution amplifier are investigated in detail, and we show that it provides a large optical gain
(
>
40
dB
∕
cm
)
across a wide
(
>
48
nm
)
spectral bandwidth in the green. The saturation characteristics of the amplifier are found to be in excellent agreement with theoretical predictions, allowing an estimate of the F8BT stimulated emission cross-section,
σ
. We find
σ
∼
1.7
×
10
−
16
cm
2
, comparable with the reported values for established laser dyes and other high-gain conjugated polymers.