The problem of the facet reflectivity of a semiconductor slab waveguide is reexamined as an extension of IkegAMi's original approach but which includes radiation-like modes. The latter are included, using a guide-within-a-guide geometry, as modes bound to a thick air-cladding guide which contains the core profile of interest. In this model with a relatively simple analysis, the coupling from the fundamental mode to radiation modes can be analyzed. The cross-coupling to the radiation modes is considered in detail for the simple double heterostructure waveguide and is shown to be important only for large core-cladding index differences and for strong modal confinement wherein it results in a true facet loss. The conditions for this are the same as for low threshold lasers so that the loss sets a maximum limit on the equivalent internal quantum efficiency. A separate one-dimensional finite element, numerical mode matching program, which treats evanescent and propagating radiation modes, is used as a comparison. The two methods of accounting for radiation modes are shown to be in good agreement: both predict reduced extremes in reflectivity when compared with the original Ikegami model. Modern graded core cases are treated as general examples along with the specific quantum well laser structures taken from the literature. These include II-VI and III-V structures spanning wavelengths from 0.5 μm to 10.0 μm.
|Number of pages
|IEEE Journal of Quantum Electronics
|Published - Aug 1993
Bibliographical noteFunding Information:
Manuscript received November 24, 1992; revised December 24, 1992. This work was supported by the National Science Foundation, ECD 8943 166, the University of Illinois Industrial Affiliates Program, and the Office of Naval Research, ”14-89-J-1286. The authors are with the Department of Electrical Engineering, University of Illinois, Urbana, It 61801. IEEE Log Number 9210241.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Electrical and Electronic Engineering