Tunable passively Q-switched ultranarrow linewidth erbium-doped fiber laser

摘要

A tunable passively Q-switched erbium-doped fiber laser with ultranarrow linewidth is proposed and demonstrated. With the single wall carbon nanotubes (SWCNTs) as the passive Q-switch, the ultranarrow linewidth laser operation is realized based on spectral filtering effect.using an ultranarrow tunable bandpass filter (UNTBF). The Q-switched laser spectrum is tunable from 1525 to 1561?nm, covering a wavelength range of 36?nm. At 1545?nm, the highest repetition rate of ~38?kHz and the lowest pulse width of 1.15?μs are obtained, with the corresponding pulse energy of approximately 0.18nJ. The linewidth measurement using self-heterodyne technique yields a linewidth value of 17.5?kHz, which may be the narrowest linewidth for a Q-switched fiber laser to the best of our knowledge.