PT Journal AU Paiella, R TI Terahertz quantum cascade lasers: Going ultrafast SO Nature Photonics JI Nat. Photon. PY 2011 BP 253–255 VL 5 DE fromIPMRAS AB A new asynchronous coherent optical sampling method allows for the direct visualization of actively mode-locked quantum cascade laser pulses at terahertz wavelengths. ER