All-Optical InAsP/InP Nanowire Switches Integrated in a Si Photonic Crystal

We report the successful demonstration of alloptical switching using a subwavelength InP/InAsP nanowire integrated in a silicon photonic crystal at telecommunication wavelengths. In this work, we employed two different hybrid nanowire cavities based on an air-trench in photonic crystals. These hybrid cavities have the advantages of both material functionality of III-V material and the low propagation loss of the silicon waveguide. The nanowire induced line-defect photonic crystal cavity shows a Q-factor of 25000, higher than the hybrid systems we previously demonstrated. The switching time is 150 ps, which is among the fastest nanowire switches reported. We found that the switching time was clearly dependent on the Q-factor. From measurements performed while changing pump power, we have estimated the switching energy to be a few hundred femtojoules. This value is lower than that of a reference silicon photonic crystal cavity without a nanowire and an air trench under the same pumping condition. This indicates that the InP/InAsP nanowire integrated in a silicon photonic crystal has potential to contribute to reducing the switching energy.