# Heat loss in Optical Fiber

I am conducting a thermal analysis of optical fibers. ( Software used AutoCAD Fusion 360)

The Inputs conditions are :

Let's assume an input power of 1250W, with an efficiency of 98%. 2% loss which becomes heat. (25W)

The internal heat of 25W at the inner core ( power loss ) gives 407.7 degrees Celcius.

Convection Coefficient of $$10W/m^2K$$ (Convection of still air)

The material of the rod I assume is glass with an emissivity of 0.9 ( Radiation ).

The temperature of the optical fiber reaches 407.7 degrees Celcius, which is inconsistent with real life. The temperature should be approximately 35 degrees Celcius? Why is this so, am I missing out on another method of heat loss? Any help will be greatly appreciated.