Thermal induced broadband all-optical switching in InP quantum dots

A broadband all-optical switch based on the thermal lens effect of InP/ZnS quantum dots (QDs) has been demonstrated. Using a pump laser at 600 nm, whose photon energy is larger than the bandgap, thermal effects induce a large nonlinear optical refraction that modulates the beam path of a probe light to form an all-optical switch. By adjusting the sizes of the QDs, the position of the bandgap can be tuned over a wide wavelength range. Thus, both the pump and the probe wavelengths can be designed for specific applications. The on/off tests of the all-optical switches demonstrate that they work well with switching rates of hundreds of Hertz. Our result demonstrates that InP/ZnS quantum dots are a good candidate material for the application of all-optical switching.