Abstract
We develop a gallium arsenide (GaAs) photonic crystal nanocavity device capable of capturing and releasing a pulse of light by dynamic control of the Q factor through free carrier photoexcitation. Unlike silicon-based devices where the performance of this dynamic optical control is limited by absorption from free carriers with nanosecond-order lifetimes, the short carrier lifetime (∼ 7 ps) of our equivalent GaAs devices enables dynamic control with negligible absorption losses. We capture a 4 ps optical pulse by briefly cycling the Q factor from 40,000 to 7900 and back just as the light couples to the nanocavity and confirm that the captured energy can be subsequently released on demand by a second injection of free carriers. Demonstrating dynamic control with negligible loss in a GaAs nanophotonic device also opens the door to dynamic control of cavity quantum electrodynamics with potential application towards quantum information processing.
Highlights
Chip-based nanophotonic devices, such as 2D photonic crystals (PCs), can confine light to within wavelength-order dimensions with extremely low loss [1,2,3,4,5]
We propose instead beginning with the system in a high Q state (Fig. 1(c)) and quickly decreasing the Q factor for only as long as necessary to couple the signal pulse to the nanocavity, having the system rapidly return to the initial high Q state as the carriers rapidly decay
Summary In conclusion, we have developed a method for dynamically capturing light in a PC nanocavity using the photo-excitation of short-lived free carriers and experimentally demonstrated its success in gallium arsenide (GaAs) based 2D PCs with carrier lifetimes of only 7 ps
Summary
Chip-based nanophotonic devices, such as 2D photonic crystals (PCs), can confine light to within wavelength-order dimensions with extremely low loss [1,2,3,4,5]. As the photon lifetime or group delay in silicon-based photonic devices has become longer, there have been several efforts to dynamically change their properties while interacting with light in order to realize novel concepts of adaptive bandwidth and adiabatic transition [6,7,8,9]. These concepts have led to demonstrations of catch and release of pulses [10,11,12], wavelength conversion [13,14,15], optical switching [16] and the manipulation of strongly coupled states [17]. As free carriers are excited extremely quickly and have nanosecond order lifetimes in silicon slabs, this produces a rapid change of index that can thereafter be approximated as constant
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