The volume of wireless tele­communication traffic is expected to surge in the near future with a continual increase in data traffic and corresponding necessary increase in bandwidth. It has therefore become inevitable to increase the photon frequency into the upper reaches of the milli­meter region, which corresponds to frequencies between 30 GHz to 300 GHz. Millimeter wave generation using photonic techniques has so far been limited to the use of near-infrared lasers that are down-converted to the mmWave region. However, such methodo­logies do not currently benefit from a monolithic architecture and suffer from the high difference in photon energies between the near-infrared and mmWave region – a quantum defect, which can ultimately limit the conversion effi­ciency.

Terahertz (THz) wave region, with photons of lower energies, is however highly adapted. Moreover, we know how to generate them thanks to a compact minia­turized device, the quantum cascade lasers (QCLs). These lasers have inherent other advantages in this respect: their ultrafast dynamics and high nonlinearities open up the possi­bility of inno­vatively integrating both laser action and mmWave generation in a single device.

Now, LPENS researchers of the Nano-THz group, in colla­boration with teams of C2N, NEST in Pisa, ONERA in Palaiseau and the University of Leeds have demons­trated intra­cavity mmWave generation within THz QCLs over the unpre­cedented range of 25 GHz to 500 GHz. Importantly, this work opens up the possi­bility of compact, low noise mmWave gene­ration using THz frequency combs. (Source: LPENS)

Reference: V. Pistore et al.: Millimeter wave photonics with terahertz semiconductor lasers, Nat. Comm. 12, 1427 (2021); DOI: 10.1038/s41467-021-21659-6

Link: Laboratoire de Physique de l’Ecole Normale Supérieure, Université de Paris, Paris, France