Fiber Mach–Zehnder interferometers fabricated by nanosecond pulses and applications in refractive index sensing

Abstract A novel and simple microfabrication method for in-line micro-cavity based fiber Mach–Zehnder interferometers (FMZIs) is proposed and demonstrated by nanosecond (ns) pulsed fibers lasers for the first time. Instead of using high-end femtosecond laser for the fabrication process, only conventional ns-pulsed fiber lasers of modest optical powers are required in our approach. Such fabricated fiber MZ interferometer has exhibited a high sensitivity of −20048 nm/RIU (refractive index unit) for the index sensing application. The achieved index sensitivity is in good agreement with the theoretical estimation.