A CRITIQUE ON THE USE OF WINDOW STRUCTURE IN TRAVELING-WAVE SEMICONDUCTOR OPTICAL AMPLIFIERS

The inclusion of window structure to the conventional design of travelling wave semiconductor optical amplifier was thought to help significantly reduce facet reflectivity. A theoretical study, in which wave propagation in the window region is also taken into consideration, shows that the significant reduction can be realized only if the window thickness can be as precisely controlled as the anti-reflection coating thickness. Since this is not viable in practice, conventional design principle and strategy are found necessary to be revised.