Time-domain response of point-defect cavities in two-dimensional photonic crystal slabs using picosecond light pulse

Time-domain responses of point-defect cavities in two-dimensional photonic crystal slabs are directly investigated. Point-defect cavities are excited by picosecond light pulses and time evolutions of the light emissions are measured by using cross-correlation method. The obtained signals clearly show delays in initial rises and tailings in later stages which reflect photon lifetimes of the cavities. The signals are analyzed by comparing with numerical simulations where Gaussian input pulses and linear responses of the systems are assumed. Photon lifetimes are evaluated to be < 1, 3, and 9 ps for the point-defect cavities having Q factors of 500, 3800, and 10 000, respectively. We believe that the results obtained here will contribute to the time-domain manipulation of photons utilizing artificial defects in photonic crystals.