A Single Longitudinal Mode Tunable Fibre Laser Based on an Opto-digital Micromirror Device Processor and Two Sub-ring Cavities

摘要

A single longitudinal mode (SLM) tunable erbium-doped fibre laser with two sub-ring cavities based on a digital micromirror device (DMD) processor is experimentally demonstrated. The DMD processor is used to select and couple any waveband from the gain spectrum of the erbium-doped-fibre laser into the main fibre ring. Two different short passive subring cavities are inserted into the main ring cavity and are used as mode filters to realize SLM lasing. By driving the opto-DMD processor with the software, the output wavelength can be generated through automatically producing reconfigurable diffraction gratings without any mechanical shift. The experimental results demonstrate that the SLM laser can be automatically tuned over the C-band with a line-width of 0.25 pm and a tuning step of 0.055 nm. The side-mode suppression ratio is above 49.00 dB, and the output power is more than 5 dBm. The centre wavelength and power fluctuations are below 0.015 nm and 0.08 dB, respectively.