The effect of elastic fatigue on the output transmission of a Mach–Zehnder interferometer comb filter

• Tunable all fiber optical comb filter based on MZI is presented.
• The effect of strain on PMF segment of the comb filter is analyzed.
• The effect of elastic fatigue on the output characteristics also is observed.
• Tuning of peak wavelength position is achieved with applying stress.

The elastic characteristics of linear birefringence and its effect upon the output of an optical fiber dual-pass MZI comb filter are theoretically and experimentally analyzed. The result shows that the linear birefringence is induced by the mutual pressure applied on fiber due to the applied stress. As a result of induced birefringence, the peak wavelength shifts continuously with the continuous change in stress up to a certain value of the applied stress. But for discrete change in stress the peak wavelength shifting is not continuous. Theoretically, the gradients of peak wavelength position shifting 0.16 nm/N and 0.36 nm/N are calculated for the maximum and minimum effective length respectively. Experimental observations of the gradients acquire values of 0.14 nm/N and 0.40 nm/N. These results might be useful for pressure sensing technique.