Optoelectronic directional couplers for optical switching fabrics

Optical switching fabrics describe arrays of interconnected optical switches that enable input signals to be directed to output ports with optimal flexibility. Such arrays avoid the use of OE conversions and circuit-switched connections by allowing the optical data stream to pass through the fabric in its original form. As such, the fabric requires very dense, low loss switches with high speed reconfigurability. Such arrays can be realized with an MEMS mirror arrays, electro-optic (EO) (8x8 LiNbO3 demonstrated) , interferometric, digital optical, liquid crystal, bubble, acoustooptic and semiconductor amplifier switches. However currently all routing is done with circuit switching. The issues are insertion loss, crosstalk, extinction ratio, polarization dependence and scalability. For high speed operation the EO switch must be used and for integration only the semiconductor approach is viable. ODIS proposes a semiconductor directional coupler that can be scaled to lengths <500um and that may be integrated with other optical and electronic circuits fabricated in POET a new platform technology for OE integrated circuits. In this SBIR, ODIS will develop the directional coupler as the key switching device within the fabric and demonstrate the potential for sub-ns switching, low insertion loss, high density and connectivity to a router processor. BENEFIT: High speed all-optical switching fabrics are critical for next generation optical routers and would be purchased by major telecommunication networking companies such as Ciena, Juniper, Cisco, Netgear etc. The optoelectronic chip developed here will outperform other optical fabrics by an order of magnitude at a substantially reduced cost. Therefore market penetration is assured. This technology platform will also solves other problems related to optical routers such as wavelength conversion, optical DRAM and high speed logic interconnections. This approach to switching fabrics will establish a new direction in the industry.