Superconducting Microdisk Cavities for THz Quantum Cascade Lasers

PROJECT TITLE :

Superconducting Microdisk Cavities for THz Quantum Cascade Lasers

ABSTRACT:

We tend to gift superconducting waveguides for terahertz (THz) quantum cascade lasers (QCLs). Double-metal waveguides offer high confinement of the optical mode and low waveguide losses that are dominated by absorption of the radiation in the metal layers. Implementing novel waveguide materials like superconductors is one method to scale back these losses. In order to prove the compatibility with the THz QCL active region and waveguide we tend to have replaced the commonly used gold or copper layers by superconducting niobium (Nb). We have a tendency to have simulated the temperature distribution inside the THz QCL so as to guage the operation conditions at that the critical temperature of the Nb layers isn't exceeded. Experimental results of THz QCLs with Nb waveguides are presented that show lasing emission despite the fact that the energy of the THz radiation of the investigated active region $f= 2.5~hboxTHz= 10.3~hboxmeV$ is more than the superconducting energy gap of Nb $a pair of Delta = a pair of.eight~hboxmeV$. Calculations show that improvements in terms of lower waveguide losses can be achieved using a superconductor with higher important temperature and thus wider superconducting gap e.g., NbTiN or $hboxMgB_2$.

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