Terahertz quantum cascade laser array with spatially-separated beams

•A compact lens-coupled THz QCL array with multiple spatially-separated beams has been realized.•Excellent emission characteristics of low divergence angles from 4.1°×3.5° to 7.2°×5.8° and multi-wavelength spectra are obtained. The angular deviation of ~ 10° between adjacent laser guarantees the spatial separation of beams without overlap.•The output intensity after lens improves dramatically for lasers at different positions with a high focusing efficiency.