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 (102, 202, 302, 402), wherein each of the multiple pixels comprises: a germanium-silicon absorption layer (106, 206, 306, 406)) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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 (102, 202, 302, 402), wherein each of the multiple pixels comprises: a germanium-silicon absorption layer (106, 206, 306, 406)) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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 (106, 206, 306, 406)) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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 (108, 110, 208, 210, 308, 310, 408, 410) 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.