Computer-controlled tunable fiber laser

Abstract

Fiber lasers have been a subject of extensive research mainly due to their natural compatibility with optical fiber communications systems and optical fiber sensors. In particular, erbium doped fiber lasers offer attractive features such as a broad emission spectrum within a range in which several fiber optic devices such as Bragg gratings are readily available. We have studied the performance of a simple computer based control system for tuning and wavelength stabilization of an erbium doped single-mode fiber laser. Tuning is achieved upon stretching a fiber grating used as one of the mirrors for the laser cavity while wavelength is monitored through an optical spectrum analyzer. The desired wavelength of emission is fed to the computer through a graphic computer interface and an actuator stretches the grating to tune the fiber laser. Once the specified wavelength is achieved the control systems stabilizes the fiber laser upon monitoring wavelength fluctuations due to parameters such as temperature variations. The response time of the system seems to be adequate for interrogation of Bragg gratings in multiplexed sensor arrangements. Accuracy for wavelength stabilization is limited only by the resolution of the optical spectrum analyzer (0.06 nm). Being a general purpose system, any other tuning methods or wavelength tracking devices such as etalons can be used. The system has therefore the potential of becoming a compact computer controlled tunable fiber laser.