Jerez González, BorjaSzedlak, RolfMartín Mateos, PedroDios Fernández, Cristina deAcedo Gallardo, PabloStrasser, Gottfied2020-11-182020-11-182018-09-07Optical and quantum electronics, 50(351), Sept. 2018, 8 pp.0306-89191572-817X (online)https://hdl.handle.net/10016/31440In this Letter, an experimental analysis for coherent multiharmonic signal generation in quantum cascade lasers is presented. The underlying principle relies on the direct modulation of the laser with a large sinusoidal wave to drive the laser above and below threshold. This generates a multiharmonic optical signal in the frequency domain as the device is forced to respond in a nonlinear fashion. The impact of the modulation parameters is assessed in the resultant optical spectrum of a continuous-wave distributed feedback quantum cascade laser. Despite not creating pulses due to the ultrafast dynamics of the laser, the results reveal that a comb structure with uniform line spacing and high phase correlation between teeth can be straightforwardly generated.8eng© Springer Science+Business Media, LLC, part of Springer Nature 2018Distributed feedback quantum cascade lasersLarge-signal modulationMultiharmonic generationOptical frequency combRadiofrequency photonicsresearch articleElectrónicahttps://doi.org/10.1007/s11082-018-1619-5open access13518OPTICAL AND QUANTUM ELECTRONICS50AR/0000022004