Changes in optical spectrum of photonic fiber with two counter propagating laser beams

摘要

Photonic fiber with single mode couplers or splitters at each fiber end can be used as a sensitive structure for fiber sensing applications. The sensitive structure is created with two DFB lasers at X = 1550 nm. Each laser is connected to opposite sides of photonic fiber provided with SM couplers. One DFB laser is isolated and its light goes through variable attenuation. Isolation is necessary for DFB laser stability. The second laser is DFB or F-P laser without any isolator. Its radiation is driven as with driven current so with DFB laser passing through photonic fiber. Small changes of DFB laser light passing through photonic fiber activate large changes in FP laser radiation. Temperature and pressure actuating on photonic fiber are examples of effects that are able to change properties of passing laser light. These changes can be measured with the help of photo detector at the second arm of SM couplers. Changes in optical spectra of F-P and DFB laser under temperature and pressure are the results.