Liquefied gallium exhibits a broad nonlinear effect at room temperature

Liquefied gallium exhibits a broad nonlinear effect at room temperature

Nikolay Zheludev and coworkers at the University of Southampton (Southampton, England) have observed a large broadband cubic nonlinearity of about 10-9 m2/V2 at the interface between glass and metallic gallium held just below the melting point. Although currently not fully understood, the nonlinearity is linked to the surface melting effect at the interface. The nonlinearity occurs at room temperature and is not constrained by material geometry so it offers significant possibilities for developing practical nonlinear devices, Zheludev said. The nonlinearity is faster than those that occur in liquid crystals and is broadband in comparison to the near-bandga¥and excitonic nonlinearities in semiconductors. It spans the range from visible to mid-IR wavelengths and is fully reversible and remains stable if the sample temperature is maintained just below the 30°C melting point of gallium.

Together with colleagues from the Optoelectronics Research Centre in Southampton, the grou¥has tried using the nonlinearity in a waveguide by forming a gallium mirror at the ti¥of a single-mode fiber. The grou¥has also demonstrated a high-contrast optical switch operating at milliwatt optical-power levels with a cut-off frequency of about 100 kHz. The switch is also capable of routing submicrosecond optical pulses, Zheludev said. The researchers have patented the nonlinearity as well as potential applications.