Wavelength division multiplexing structure

A Wavelength Division Multiplexing (WDM) structure, comprising:

• a first wavelength division multiplexer and a second wavelength division multiplexer;
• wherein each of the first wavelength division multiplexer and the second wavelength division multiplexer comprises N filtering units, a branch side interface connected to each of the filtering units, and a line side interface, N being a positive integer, each of the filtering units corresponds to one central wavelength, the line side interface of the first wavelength division multiplexer and the line side interface of the second wavelength division multiplexer are connected by an optical fiber;
• the N filtering units are divided into multiple filtering unit groups based on a central wavelength corresponding to each of the filtering units, and the multiple filtering unit groups are cascaded in series, or, the multiple filtering unit groups are cascaded in a series-parallel combination, and filtering units in each filtering unit group are cascaded in series;
• and
• wherein a cascade mode and/or cascade position corresponding to each of the filtering units in the first wavelength division multiplexer and the second wavelength division multiplexer is at least related to a central wavelength corresponding to the filtering unit, so that a total power budget of a channel corresponding to each central wavelength is less than or equal to a first power threshold, and a difference between total power budgets of respective channels corresponding to different central wavelengths is less than a second power threshold;
• wherein pairwise channel insertion losses corresponding to different groups of central wavelengths in the first wavelength division multiplexer and the second wavelength division multiplexer are in non-uniform distribution;
• pairwise channel insertion losses corresponding to a same group of central wavelengths in the first wavelength division multiplexer and the second wavelength division multiplexer are in relatively uniform distribution.