A wavelength selective switch includes an optical fiber array, a multiplexing/demultiplexing component, and a transmission direction adjustment component. The optical fiber array includes a first optical fiber and at least one second optical fiber. The first offset is used to compensate for a second offset of a diffraction spectrum generated when a plurality of single-wavelength optical signals obtained after an optical input signal is processed by the multiplexing/demultiplexing component arrive at the transmission direction adjustment component, so that the second offset of the diffraction spectrum of the plurality of single-wavelength optical signals arriving at the transmission direction adjustment component is 0 or may be ignored. An optical system has a simple structure, and no optical element needs to be added. This increases optical design freedom, facilitates optical path system commissioning, and reduces reliability risks and costs of subsequent products.

A wavelength selective switch comprising a 2D fiber array and a dispersion unit, the dispersion unit is configured to disperse the first beam output from one of the fibers in the 2D fiber array, and generate a plurality of first sub-beams, the dispersion unit is also configured to combine at least a portion of the plurality of first sub-beams to generate a combined second beam, and to transmit the second beam to another fibers in the 2D fiber array; the 2D fiber array comprising a first column of fibers and a second column of fibers, fibers in the second column of fibers and fibers in the first column of fibers are alternately arranged in a switching direction, the second column of fibers is offset from the first column of fibers by a predetermined spacing in a dispersion direction, the dispersion direction is perpendicular to the switching direction.

An end-capped optical fiber includes: an optical fiber including a first portion comprising a first core and a first cladding surrounding the first core, and a second portion comprising a second core and a second cladding surrounding the second core; and an end cap comprising a first face connected to an end face of the second portion and a second face located on a side opposite the first face, wherein: a diameter of the first core is constant along an optical axis of the first core; a diameter of the second core gradually increases toward the end cap; the end cap includes a convex lens; the second surface includes a convex lens surface of the convex lens; and a focal point of the convex lens is located inside the optical fiber and away from the end face of the second portion.