Fig. 4: Linearity, scalability, and benchmarking of FeFET Pockels photonic memory.
a Maximum resonance shift as function of coverage, where coverage is defined by the angle of covering of the MRR divided by 360°. The coverage cannot reach 100% due to the protective coupling region of the MRR, which should not be covered by other materials. b SEM micrograph in false color of a FeFET Pockels photonic memory controlled by three independent FeFETs, i.e. FeFET-1, FeFET-2, and FeFET-3. The white represents the straight waveguide and MRR. Source and drain electrodes are presented by yellow, while top gates are presented by blue. The channel has two layers, including ITOx and IGZO, which are presented by light blue. The gradient yellow and red represents HZO ferroelectric layer. There is an uncolored fourth FeFET outside the open SiO₂ window, which does not have an effect. (S: source, G: gate, D: drain) (c) Change of optical states modulated by three independent FeFETs on a shared MRR where separate pulses with increasing amplitude are applied. The resonance shift is attributed to the combined effect of the three FeFETs, with each optical state being set by a negative WRITE pulse following a positive RESET pulse. Following a pre-operation of ‘initialization’, the multi-state linear operation, coordinated by three FeFETs, is achieved with a high R2 equal to 0.98323. (λ: wavelength) (d) Histogram showing the reproducibility of reaching each state when starting from ready state for linear operation. 13 distinct states are observed. Different colors correspond to various optical states induced by different FeFETs. e FeFET Pockels photonic memory (red) benchmarked against reported non-volatile photonic memories (orange)7,11,14,15,16,39,40,41,42,43,44,45, in terms of capacity, power consumption, and endurance. The size of each dot represents the capacity.
