Fig. 2. Photovoltaic modulation working principle.
a Electrical energy consumption and demonstrated data rate for the lowest power optical modulators reported in the literature33–41. Devices fabricated in silicon (blue) and other material platforms (red) are shown. Photovoltaic (PV) modulation (gray shaded area) can achieve orders of magnitude lower power consumption at speeds below ≈3 GHz, approaching the Landauer limit for binary switching (dashed purple line). Black diamonds show experimentally obtained optical modulation presented in this work. Supplementary Tables 1 and 2 show more information on the different devices. b Measured I–V curves of two different silicon photonic resonant modulators under illumination. Photocurrent generation is clear. Energy harvesting is possible when operating the device in the gray shaded area, while conventional modulators operate in the yellow shaded area. The inset shows the measurement setup. More information is given in Supplementary Discussion 2. c Conventional modulation driving scheme. The VDD source needs to provide the energy required to charge the modulator capacitance and that associated with the work on photogenerated charges. d PV modulator driving scheme. The photocurrent is used to self-charge the modulator capacitance and the transistor channel, greatly reducing the electrical energy provided by the driver.