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Is Vanadium Dioxide credible for ultrafast photonic switching?


Ever since picosecond optical switching of the semiconductor-to-metal transition in vanadium dioxide (VO 2 ) was discovered two decades ago, there has been growing interest in the potential for photonic applications of this deceptively simple oxide.  But until recently, it appeared that the bottleneck in switching times for the rutile-to-monoclinic structural transition – of order hundreds of picoseconds at the very least – counseled a skeptical, if suspended, judgment.  Recent demonstrations of a short-lived metallic monoclinic state in VO 2 suggest that the potential indeed real, provided that high-quality VO 2 thin films can integrated in silico .   After motivating the idea of all-optical photonic switching in silicon from recent results, I will describe direct and indirect evidence for the monoclinic metallic state, and then consider the materials issues that will have to be solved to realize hybrid silicon-VO 2 photonics in practice.