In fiber optics, most of the literature says that single-mode (SM) fiber allows only 1 mode of light to propagate/travel within, then how the same SM fiber allows WDM or DWDM, which
![electromagnetism - Window choice in single mode or multi mode optical fiber - Physics Stack Exchange electromagnetism - Window choice in single mode or multi mode optical fiber - Physics Stack Exchange](https://i.stack.imgur.com/cFQX3.png)
electromagnetism - Window choice in single mode or multi mode optical fiber - Physics Stack Exchange
![Fiber dispersion and attenuation characteristics for single-mode fibers. | Download Scientific Diagram Fiber dispersion and attenuation characteristics for single-mode fibers. | Download Scientific Diagram](https://www.researchgate.net/publication/3244500/figure/fig7/AS:667846875049999@1536238511502/Fiber-dispersion-and-attenuation-characteristics-for-single-mode-fibers.jpg)
Fiber dispersion and attenuation characteristics for single-mode fibers. | Download Scientific Diagram
![a) Experimental of our multi-wavelength imaging system; SMF, single... | Download Scientific Diagram a) Experimental of our multi-wavelength imaging system; SMF, single... | Download Scientific Diagram](https://www.researchgate.net/publication/349292473/figure/fig4/AS:1022266057965570@1620738629392/a-Experimental-of-our-multi-wavelength-imaging-system-SMF-single-mode-fiber-FC.png)