Abstract

Ultrafast fibre lasers that combine GHz mode-locking with wavelength tuning have widespread applications in fields such as spectroscopy, telecommunications, frequency metrology and optical coherent tomography. The cavity length of conventional fibre lasers passively mode-locked at GHz rates is however only a few cm [1,2], which challenges the wavelength tuning capability of such lasers. Recently, pulsed lasers stably mode-locked at few-GHz rates were successfully produced in few-meter-long cavities, the mode-locking mechanism being a GHz acoustic resonance in the solid-glass core of a photonic crystal fibre (PCF). This resonance forces the laser to mode-lock at a very high harmonic of its fundamental round-trip frequency [3,4]. Here we report that by inserting a tunable optical filter in the laser cavity, wideband wavelength tuning (1535 nm – 1563 nm) of this laser can be achieved while maintaining mode-locking.

© 2015 IEEE