The reason why fiber optic cables cannot be bent beyond a certain angle while transmitting data through them is due to a phenomenon known as "total internal reflection."
Fiber optic cables consist of a core, which is a thin strand of optically transparent material, surrounded by a cladding layer with a lower refractive index. Light signals, carrying the data, are transmitted through the core of the fiber optic cable using principles of total internal reflection.
When light enters the core of the fiber optic cable, it encounters the interface between the core and the cladding. Total internal reflection occurs when the incident angle of light at this interface is greater than the critical angle. The critical angle is the minimum angle at which light can travel through the core without escaping through the cladding.
If the fiber optic cable is bent beyond a certain angle, the light rays within the cable will reach the core-cladding interface at angles larger than the critical angle. As a result, instead of undergoing total internal reflection, some of the light rays will escape through the cladding, leading to signal loss and degradation.
The maximum allowable bending angle of a fiber optic cable is determined by factors such as the numerical aperture of the cable (which relates to the refractive index difference between the core and cladding), the size of the core, and the quality of the cable's design and construction. Generally, fiber optic cables are designed to withstand a certain minimum bend radius specified by the manufacturer to ensure optimal signal transmission and minimize loss.
It's worth noting that newer fiber optic cables may be more flexible and have improved bending characteristics, allowing them to be bent more tightly without significant signal loss. However, it is still important to adhere to the manufacturer's guidelines regarding bending radius to maintain the integrity of the data transmission.