Isolator-free, widely tunable thulium/holmium fiber laser


  • Anir Syazwan Sharbirin University of Malaya
  • Mohammad Faizal Ismail University of Malaya
  • Harith Ahmad University of Malaya



Tunable fiber laser, thulium, holmium, theta cavity, isolator-free


An isolator-free thulium/holmium-doped fiber laser with a broadly tunable wavelength output is proposed and demonstrated for the first time. A theta resonator configuration is implemented in order to produce rectification of lasing direction without the need for an optical isolator, thus, making it a more cost-effective setup in comparison to the conventional ring resonator. Over 160 nm of wavelength tunability can be generated, which covers a huge range of the two-micron region starting from 1888 nm up to a maximum of 2048 nm. The laser exhibits excellent wavelength control with its short-range wavelength tuning capability, whereby the shortest tuning spacing obtainable is as small as ~0.1 nm. The tunable laser peaks maintain a strong optical-signal-to-noise (OSNR) value for the whole tuning range, reaching more than 60 dB, also a full-width half-maximum (FWHM) value less than ~0.2 nm with a maximum output power of 6.82 mW. The isolator-free cavity indicates a significant improvement in the slope efficiency of the laser in comparison to a ring cavity setup with similar components. The proposed laser would have substantial use as a laser seed for application in sensing and spectroscopy.

Author Biographies

Anir Syazwan Sharbirin, University of Malaya

Photonics Research Center

Mohammad Faizal Ismail, University of Malaya

Photonics Research Center

Harith Ahmad, University of Malaya

Photonics Research Center


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