Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 23

An optical source is selected from a batch characterized as having lifetimes that follow a slow internal degradation mode. The -3-dB mean time to failure of these devices at room temperature is specified as 5 × 10 4 h. If the device emits 1 mW at room temperature, what is the expected optical output power after 1 month of operation, after 1 year, and after 5 years