We report enhanced broadband terahertz (THz) generation and detailed characterization from the interaction of femtosecond two-colour laser pulses with thin transparent dielectric tape target in ambient air. The proposed source is easy to implement and exhibits excellent scalability with laser energy. Spectral characterization using Fourier transform spectrometer reveals yield enhancement of more than 150% in the THz region of 0.1–10 THz with respect to conventional two-colour laser plasma source in ambient air. Further, the source spectrum extends up to 40 THz with an enhancement of flux >30%. Experimental results, well supported with two-dimensional particle-in-cell simulations, establish that the transient photo-current produced by the asymmetric laser pulse interaction with air plasma as well as near solid density plasma formed on the tape surface is responsible for the enhanced terahertz generation. The source will be useful for the multidisciplinary activities and ongoing applications of the laboratory-based terahertz sources.

我们报告了增强的宽带太赫兹 (THz) 生成和飞秒双色激光脉冲与环境空气中薄透明介电带目标相互作用的详细表征。所提出的光源易于实现，并且具有出色的激光能量可扩展性。使用傅立叶变换光谱仪的光谱表征显示，相对于环境空气中的传统双色激光等离子体源，在 0.1-10 THz 的 THz 区域内，产量提高了 150% 以上。此外，源频谱扩展到 40 THz，通量增强 >30%。实验结果，得到了二维细胞内粒子模拟的有力支持，确定由不对称激光脉冲与空气等离子体相互作用产生的瞬态光电流以及在磁带表面形成的近固体密度等离子体是增强太赫兹产生的原因。该源将有助于基于实验室的太赫兹源的多学科活动和持续应用。