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
![Fibre optic cable single mode OS2 9/125 μm (OS1 compatible) indoor/outdoor - 12 fibres Euroclass Cca - loose tube - 0 325 26 - Legrand Fibre optic cable single mode OS2 9/125 μm (OS1 compatible) indoor/outdoor - 12 fibres Euroclass Cca - loose tube - 0 325 26 - Legrand](https://www.legrand.com/ecatalogue/media/catalog/product/cache/4/image/650x650/9df78eab33525d08d6e5fb8d27136e95/l/g/LG-032526-WEB-R.jpg)
Fibre optic cable single mode OS2 9/125 μm (OS1 compatible) indoor/outdoor - 12 fibres Euroclass Cca - loose tube - 0 325 26 - Legrand
![Amazon.com: BEYONDTECH LC to LC Fiber Patch Cable Single Mode Duplex - 1m (3.28ft) - 9/125um OS1 LSZH PureOptics Optic Patch Cable Series : Electronics Amazon.com: BEYONDTECH LC to LC Fiber Patch Cable Single Mode Duplex - 1m (3.28ft) - 9/125um OS1 LSZH PureOptics Optic Patch Cable Series : Electronics](https://m.media-amazon.com/images/I/71RKqTMlJTL._AC_UF894,1000_QL80_.jpg)