Abstract

Laser-based frequency combs play an important role in applications as spectroscopy. In the visible and infrared regime devices are already commercially available. Since a lot of rotation and vibration frequencies of gases lie in the THz domain, it is desirable to realize a powerful and broad frequency comb at such frequencies. THz Quantum cascade lasers (QCLs) are able to operate in this frequency domain and have been recently actually mode-locked by direct modulation [1,2]. As a first step in the realization of a broadband terahertz frequency comb (teracomb) it is therefore necessary to develop a QCL active region design which provides broadband spectra in the frequency domain. Previous results have been achieved employing on a heterogeneous cascade design, which resulted in a bandwidth of 1 THz centered around a frequency of 2.7 THz [3].

© 2013 IEEE