Optically pumped organic distributed feedback (DFB) lasers have been widely explored for label-free biosensing applications, but the pursues for further improved performances are considerably hindered by the trade-off between the lasing threshold and optical sensitivity. To address this challenge, a spin-coated organic DFB biosensor featuring an ultraviolet (UV) nanoimprinted polymer substrate with extremely low refractive index (RI) of 1.34 is fabricated. Owing to the low RI, the device yields both a low lasing threshold of 0.31 μJ/pulse and a high bulk sensitivity of 45.5 nm/RIU for transverse electric (TE) mode and 70.2 nm/RIU for transverse magnetic (TM) mode. Compared with a conventional DFB sensor based on a substrate with a RI of 1.51, the proposed device demonstrates a threshold reduction of over 75% and an almost 3-fold increase in bulk sensitivity. This remarkable improvement is attributed to the effect of mode energy squeezing which extracts a large amount of lossy energy from the substrate into the useful gain layer and superstrate. Additionally, the non-specific biomolecule detection of bovine serum albumin (BSA) is successfully demonstrated using the presented device.

光学泵浦有机分布反馈（DFB）激光器已广泛用于无标签生物传感应用，但是激光阈值和光学灵敏度之间的权衡极大地阻碍了进一步提高性能的追求。为了解决这个挑战，制造了具有紫外线（UV）纳米压印聚合物基板的旋转涂覆有机DFB生物传感器，该基板具有1.34的极低折射率（RI）。由于低RI，该器件既产生0.31μJ/脉冲的低激射阈值，又产生横向电（TE）模式的高体积灵敏度45.5 nm / RIU和横向磁（TM）模式的70.2 nm / RIU。与基于RI为1.51的基板的传统DFB传感器相比，拟议中的设备显示阈值降低了75％以上，而体积灵敏度几乎提高了3倍。这种显着的改善归因于模态能量压缩的效应，该效应压缩了从衬底到有用增益层中的大量损耗能量并覆盖了衬底。另外，使用提出的装置成功地证明了牛血清白蛋白（BSA）的非特异性生物分子检测。