Engineering the temporal dynamics of all-optical switching with fast and slow materials
Soham Saha, Benjamin T. Diroll, Mustafa Goksu Ozlu, Sarah N. Chowdhury, Samuel Peana, Zhaxylyk A. Kudyshev, Richard D. Schaller, Zubin Jacob, Vladimir M. Shalaev, Alexander V. Kildishev, Alexandra Boltasseva
Abstract
All-optical switches control the amplitude, phase, and polarization of light using optical control pulses. They can operate at ultrafast timescales - essential for technology-driven applications like optical computing, and fundamental studies like time-reflection. Conventional all-optical switches have a fixed switching time, but this work demonstrates that the response-time can be controlled by selectively controlling the light-matter-interaction in so-called fast and slow materials. The bi-material switch has a nanosecond response when the probe interacts strongly with titanium nitride near its epsilon-near-zero (ENZ) wavelength. The response-time speeds up over two orders of magnitude with increasing probe-wavelength, as light's interaction with the faster Aluminum-doped zinc oxide (AZO) increases, eventually reaching the picosecond-scale near AZO's ENZ-regime. This scheme provides several additional degrees of freedom for switching time control, such as probe-polarization and incident angle, and the pump-wavelength. This approach could lead to new functionalities within key applications in multiband transmission, optical computing, and nonlinear optics.