High-Speed and Low-Power Silicon Optical Phased Array Based on the Carrier-Depletion Mechanism

We demonstrate a silicon
$1\times 64$
optical phased array by using carrier-depletion-based phase shifters. The 5-mm-long phase shifter exhibits an electro-optic bandwidth of 700 MHz, a modulation efficiency of 2.3 V.cm, and an ultra-low power consumption of < 0.45 nW/
$\boldsymbol {\pi }$
. A steering range of ±18° is realized in the phased-array axis by tuning the phase of each antenna. Besides, the beam steering in the other (wavelength-controlled) axis by tuning the wavelength achieves a dispersion efficiency of 0.17° /nm. Although the carrier-depletion effect induces a nonuniform optical amplitude distribution among the antenna array, the OPA chip is still able to form high-quality far-field beam patterns with side lobe suppression ratios of
$\boldsymbol {\sim }10$
dB. Our measurement and simulation results indicate that the carrier-depletion-based OPA is a promising candidate for future high-speed and power-efficient solid-state Lidars.