Investigation of axial strain effects on microwave signals from a PM-EDF short cavity DBR laser for sensing applications

• Main Authors: Jiang, M., Dinh, Xuan Quyen, Shum, Perry Ping, Molin, S., Wu, Z. F., Nouchi, P.
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/98830; http://hdl.handle.net/10220/13465
• Institution: Nanyang Technological University

The effects of axial strain on beating frequency from a short cavity polarization-maintaining erbium-doped fiber (PM-EDF) based distributed Bragg reflector (DBR) laser were investigated theoretically and experimentally for the first time. This type of single-mode DBR fiber laser based ultrasensitive sensor has been extensively developed for measuring kinds of measurands, but the cross-sensitivity of axial strain was usually ignored. A DBR fiber laser with an effective cavity length of $sim$1 cm formed by a pair of FBGs written on a PM-EDF was fabricated for demonstration. This laser operated in dual-polarization single-longitudinal mode stably. The frequency of the beating signal generated by two orthogonal polarizations was found to be proportional to the axial strain applied on the cavity. A linear strain sensitivity of 0.640 $hbox{GHz/m}varepsilon$ was obtained, with a fiber birefringence of around 8.65e-5. For the fiber with larger birefringence, the sensitivity to the axial strain will be increased. So the effects of axial strain should be considered when the structure is utilized as a high-resolution sensor, especially for a polarization-maintaining system. The single-mode DBR laser made of high birefringent fibers also has a potential application in frequency tunable microwave generation.