Calculation of losses in the double metal waveguide of a THz QCL by modified Marcatili method

Abstract

In this work, we report the modification of Marcatili method that allows us to perform a correct calculation of the loss parameter in a double metal (DM) waveguide of a terahertz quantum cascade laser (THz-QCL). The approximation used is based on the introduction of two metallic boundary conditions (or Leontovich conditions) in the region of metal contacts, as well as the calculation of the dielectric constant of the active region in the effective medium approximation. To set up the dielectric permittivity of the active region, in addition to the effective medium approximation, the dielectric constant of each layer of the QCL cascade was calculated using the Drude-Lorentz formula.
In the obtained model, a QCL with a DM waveguide was initially considered without additional thin heavily doped layers, providing ohmic contact with the metal. The presence of these layers can be taken into account in our model using their equivalent circuit, which ultimately changes the effective value of the surface impedance of the metal contact. Despite the fact that the thin heavily doped semiconductor layer had a very weak effect on the final losses, the developed method can be very useful for taking into account the metal contact area, especially when it contains thin layers of different metals. The advantage of the developed approach is a significant reduction in computation time, since only algebraic transcendental equations need to be solved numerically, which requires much less computing power compared to the numerical solution of the two-dimensional Helmholtz equation.

Speaker

Bogdan A. Zhmud
V.G. Mokerov Institute of Ultra-High Frequency Semiconductor Electronics of the RAS
Russia

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