An imaging system comprising: a transmitter unit including one or more light sources; a receiver unit comprising an image sensor comprising multiple pixels on a silicon semiconductor substrate , wherein each of the multiple pixels comprises: a germanium-silicon absorption layer ) coupled to the silicon semiconductor substrate, wherein the germanium-silicon absorption layer comprises a GeSi alloy with composition ranging from more than 10% Ge to 100% Ge; one or more first switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a first control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a first output signal to a first readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate; and one or more second switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a second control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a second output signal to a second readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate. a transmitter unit including one or more light sources; a receiver unit comprising an image sensor comprising multiple pixels on a silicon semiconductor substrate , wherein each of the multiple pixels comprises: a germanium-silicon absorption layer ) coupled to the silicon semiconductor substrate, wherein the germanium-silicon absorption layer comprises a GeSi alloy with composition ranging from more than 10% Ge to 100% Ge; one or more first switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a first control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a first output signal to a first readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate; and one or more second switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a second control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a second output signal to a second readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate. a germanium-silicon absorption layer ) coupled to the silicon semiconductor substrate, wherein the germanium-silicon absorption layer comprises a GeSi alloy with composition ranging from more than 10% Ge to 100% Ge; one or more first switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a first control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a first output signal to a first readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate; and one or more second switches arranged in the germanium-silicon absorption layer, the silicon semiconductor substrate, or both thereof, configured to receive a second control signal at the germanium-silicon absorption layer or the silicon semiconductor substrate and output a second output signal to a second readout circuit through the germanium-silicon absorption layer or the silicon semiconductor substrate. <EOS>