Broadband, Integrated, Micron-Scale, All-Optical Si3N4/VO2 Modulators with pJ Switching Energy

The expansion of optical network traffic demands the implementation of all-optical signal processing functions such as switching and modulation within the network nodes to scale data speeds and curb power consumption. Toward this end, we experimentally demonstrate ultracompact all-optical modulators based on vanadium dioxide that can be operated by broadband control (800-1000 nm) and signal (1500-1600 nm) wavelengths and are simultaneously switched by pulse energies as low as 6.4 pJ. The devices are integrated on-chip and enable planar propagation of both control and signal light beams. For a 4 mu m length modulator, the extinction ratio is 1.68 dB/mu m and the insertion loss is 0.98 dB/mu m at lambda = 1550 nm. To our knowledge, these characteristics together have not been demonstrated previously in a single device. Furthermore, the extinction ratio, switching energy, and switching efficiency have been observed to depend on the modulator length in subtle ways, which is due to the finite distance required for the electromagnetic fields to reach steady-state within the modulator section.