Example optical devices are described. One example optical device includes a receiver. The receiver includes a photodetector, a first amplifier, a second amplifier, and a controller, where the photodetector is coupled to the first amplifier, the first amplifier is coupled to the second amplifier, and the first amplifier and the second amplifier are separately coupled to the controller. The controller is configured to control a gain of the first amplifier and a gain of the second amplifier based on a preset arrival time of an optical signal and a gain intensity corresponding to the optical signal. The photodetector is configured to receive the optical signal and convert the optical signal into a current signal. The first amplifier is configured to convert the current signal into a first voltage signal. The second amplifier is configured to convert the first voltage signal into a second voltage signal.