at least one processor; and

a storage device coupled to the at least one processor and storing instructions for execution by the at least one processor to cause the at least one processor to:

generate narrow optical pulse signals with high stability and low phase noise through an optical frequency comb;

divide the narrow optical pulse signals output by the optical frequency comb into two channels through a first optical distribution unit, wherein one channel of the narrow optical pulse signals is output to a first photoelectric conversion unit, and the other channel of the narrow optical pulse signals is output to an optical frequency doubling/dividing unit;

perform photoelectric conversion on the narrow optical pulse signals transmitted by the first optical distribution unit through the first photoelectric conversion unit, and output an electrical frequency comb;

generate a frequency-shift driving electrical waveform for driving an optical frequency-shift combining optical circuit according to the electrical frequency comb through a frequency-shift drive circuit;

perform frequency doubling or dividing on a repetition frequency of the narrow optical pulse signals output by the optical frequency comb through the optical frequency doubling/dividing unit;

divide optical pulse signals output by the optical frequency doubling/dividing unit into two channels through the optical frequency-shift combining optical circuit, wherein one channel of the optical pulse signals is optically frequency-shifted by driving of the frequency-shift driving electrical waveform, and is combined with the other channel of the optical pulse signals that is not frequency-shifted for output;

perform the photoelectric conversion on the combined optical pulse signals, and output an electrical waveform through a second photoelectric conversion unit; and

perform an electrical process on the electrical waveform, and obtain an electrical waveform with a specific frequency spectrum through a second electrical processing circuit.