Design Of Carrier-injection MMI Optical Switch

With the development of optical fiber communications, the function of optical switch and switch array is becoming increasingly prominent since they serve as key devices for optical communication system.They play an important role in the applications including optical cross connection (OXC), optical add-drop multiplexing (OADM) and natural repair protection.Various kinds of optical switches have been proposed with low levels of crosstalk, insertion loss and dependence on the polarization state, but most of their switching speed are not high enough and the respond duration are often in the ms-range .If we use the carrier-injection modulation , the switching speed is therefore determined by the life of the carrier , and in this case the respond duration is easy to reach ns-range. Nowadays, the waveguide devices based on GaAs and InP materials have become the main research direction of high speed switches.Multimode (MMI) devices, which are based on the self imaging effect, have many merits, such as compact size, low insertion loss, ease of production and good fabrication tolerances. The MMI devices are of great prospect in integrated optics.At first, based on the theory of self-imaging effect and carrier injection effect, we present new structures of 2×2 and 3×3 MMI optical switches, and we also do research on the two—wavelength switch . Then we use the Beamprop to simulate and optimize ,and the final simulation results are very good: for the 2×2 MMI optical switch, the extinction ratio is -48 dB and the insertion loss is 0.05 dB;for the 3×3 MMI optical switch, the extinction ratio is -45 dB and the insertion loss is 0.15 dB. The test results show that the devices can achieve our design object, which means that our design is feasible.Besides these, we also do some work about the fabrication hoping to provide a solid base for the high speed switch research in our lab and get a good result in the future.