Abstract

The availability of suitable electro optical switches is one of the main conditions for the implementation of optical networks based on III-V semiconductor material. Especially for telecommunication applications, switches are indispensable components in, for example, cross-connects, add-drop nodes, transceivers and wavelength routers. The benefit of using an InGaAsP film layer, instead of an MQW film layer, is the lower absorption loss and the possibility to integrate active and passive structures in a single epitaxial step. The advantage of a Mach-Zehnder switch is that it changes the refractive index by reverse biasing a diode instead of injecting a current like in certain Digital Operating Switches (DOS) 192. Reverse biasing enables higher switching frequencies and leads to lower heat dissipation. Because the present fibre network does not maintain the state of polarization, independency of polarization is one of the main properties of a switch. A possible disadvantage of a single 2x2 Mach-Zehnder switch is that a polarization independent crosstalk lower than -20 dB is hard to realize. On the contrary the crosstalk can easily be enhanced by a factor of two using dilated schemes3.4.

© 1996 Optical Society of America