Ultra-small, self-holding, optical gate switch using Ge₂Sb ₂Te₅ with a multi-mode Si waveguide

We report a multi-mode interference-based optical gate switch using a Ge₂Sb₂Te₅ thin film with a diameter of only 1 μm. The switching operation was demonstrated by laser pulse irradiation. This switch had a very wide operating wavelength range of 100 nm at around 1575 nm, with an average extinction ratio of 12.6 dB. Repetitive switching over 2,000 irradiation cycles was also successfully demonstrated. In addition, selfholding characteristics were confirmed by observing the dynamic responses, and the rise and fall times were 130 ns and 400 ns, respectively.