Optical pulses are subject to distortion and stretching as they pass through optical filters and optical fibers over long distances.
(https://github.com/tacticstactics/Optical-pulse-broadening/blob/4f1e0422b0de5515737d8783b0ee29195dfa3780/optical_pulse_broadening_optical_filter.ipynb)
The optical filter is an Infinite Impulse Response (IIR) composed of a dielectric coating.
The transmitted light and the reflected light are subjected to phase difference, which causes the light pulse to be deformed.
(https://github.com/tacticstactics/Optical-pulse-broadening/blob/9fda7b8744bb1f8f5890dfdb23fe4925a596eed4/optical_pulse_broadening_optical_fibers.ipynb)
When light passes through an optical material, it is subjected to a phase difference according to the wavelength dependence of the refractive index.
In materials with large dispersion, the longer the distance, the longer the pulse.
