Enhancing all-optical switching by localizing the control and signal light fields in the same defect region

We suggest an efficient mechanism for all-optical switching in one-dimensional photonic heterostructures based on the combined use of two resonant modes that have strong enhancement of their electric fields in the same defect region. By exciting the low-quality resonant mode with the low-intensity pump beam, one can very efficiently shift the spectral position of the high-quality resonant mode and thus control the propagation of a signal beam. For a AlGaAs/SiO2 heterostructure with two GaAs defect layers, we numerically demonstrate all-optical switching at a peak pumping intensity lower than 20 mW/mm2. Moreover, it is of great benefit to practical application that the frequency interval between the two resonant modes is adjustable in a wide range.