Terahertz quantum cascade lasers operating above liquid nitrogen temperature

THz Quantum Cascade Laser Operating Frequency Comb Over Near-full-current Dynamic Range

“…The development of THz OFCs is, nevertheless, once greatly limited by the lack of high-power and compact light source. In recent years, the continuous maturity of quantum cascade lasers (QCLs) [5][6][7][8] from mid-infrared to the THz spectral range provides an opportunity for advancing the development of OFCs by a mechanism of intracavity nonlinear four-wave mixing and injection locking [9]. However, emergence of more promising THz QCL OFCs toward yielding more stable comb operating, wider current dynamic range and spectral range [10][11][12], higher output power [13] and narrower beam divergence is still expected for further application.…”

“…But, the optical power of THz OFCs based on MM waveguide is usually limited to only a few mWs [18], threshold current density exceeds 100 A•cm −2 , and, what is more, the longitudinal far field divergence angle is approximately 180° [19]. On the contrary, THz QCLs with the semi-insulated surface plasma (SISP) waveguide [5,20,21]show advantages in these aspects.…”

High-Power Distributed Feedback Terahertz Quantum Cascade Lasers

“…Here, we present metalstripe surface grating structure, where the grating peaks are covered with metal and the grating grooves are etched through the highly doped semiconductor layer above the laser active region. The QCL wafer structure adopted here is similar to [11] and centered on 97 μm. Three different grating periods of 13, 13.2, and 13.4 μm were employed in our experiment according to the calculated effective index.…”