Tuning of optical fiber laser based on super-mode interference in a seven-core fiber

Abstract

Tuning of optical fiber laser emissions based on super-mode interference in a seven core fiber (SCF) is presented. This super-mode interference is generated by a super-mode Mach–Zehnder interferometer constructed with a few millimeters of SCF spliced between two single mode fibers (SMFs). In the SCF, two super-modes are exited via the fundamental mode of the SMF. Then, an interference pattern caused to the optical path difference between super-modes is generated at the final of the SCF, which is collected with the spliced SMF. This interference pattern induces and tunes laser line emissions by adjusting the laser cavity losses in an optical fiber laser. By bending the Mach–Zehnder interferometer, a wavelength shift of the interference pattern is induced, which in turn causes a wavelength shift of the laser cavity losses and, therefore, a displacement of the laser wavelength emission. Laser line emissions were tuned by linear factors of around 0.91 nm mm−1, and the switching of simultaneous emissions was also obtained. The stability and reliability of the laser emission on the proposed method are also discussed.