Electromagnetic modeling of terahertz quantum cascade laser waveguides and resonators

• Main Author: Kohen, Stephen Michael, 1980-
• Other Authors: Qing Hu.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2005
• Subjects: Electrical Engineering and Computer Science.
• Online Access: http://hdl.handle.net/1721.1/18058

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004. === Page 108 blank. === Includes bibliographical references (p. 103-107). === Finite-element numerical modeling and analysis of electromagnetic waveguides and resonators used in terahertz (THz) quantum cascade lasers (QCLs) is presented. Simulations and analysis of two types were performed: two-dimensional waveguides, and two- and three-dimensional resonators. Both metal-metal and semi-insulating (SI) surface-plasmon geometries were investigated. Waveguide simulations extend previous one-dimensional analyses to two dimensions; resonator simulations in two and three dimensions are presented for the first time. The waveguide simulations quantitatively show when two-dimensional effects become non-negligible in their effect titatively show when two-dimensional effects become non-negligible in their effect on the figure-of-merit relative to previous one-dimensional analyses. The resonator simulations quantitatively show the hybrid optical/microwave nature of THz facet reflectivities, demonstrating that both the effective index method and the impedance mismatch method are poor methods in calculating mirror reflectivities for metal-metal waveguides in the THz region. The effective index method is shown to still be valid for SI surface-plasmon waveguides. In addition, simulated radiation patterns are presented for both waveguiding structures. === by Stephen Michael Kohen. === S.M.