Heterogeneous Terahertz Quantum Cascade Laser for Ultra-Broadband Emission

Broadband emission in the terahertz spectral region is a prerequisite for applications such as spectroscopy or white light sources. Terahertz quantum cascade lasers provide high output powers combined with a compact design in this frequency range. Since the emission wavelength can be tailored by bandstructure engineering in these devices, multiple active region designs emitting at different wavelengths can be combined in a single structure [1]. The formation of frequency combs also benefits from a broadband gain profile through the connected frequency dependent dispersion [2]. Here, we present a heterogeneous terahertz quantum cascade laser consisting of five individual active regions (ABCDE). The devices lase in pulsed and continuous-wave operation and emit in a spectral range from 1.9-4.5 THz, covering a bandwidth of 1.37 octaves [3].