Switchable and tunable orthogonal single-polarization dual wavelength SLM fiber laser based on parity-time symmetric system and PM-FBG

• Published in: Optics and laser technology 2023-11, Vol.166, p.109695, Article 109695
• Main Authors: Lv, Yanzhi, Yin, Bin, Wang, Muguang, Li, Haisu, Gao, Mingquan, Sang, Guofeng, Wang, Qichao, Wu, Songhua
• Format: Article
• Language: English
• Subjects: Orthogonal single polarization; Parity-time symmetric system; Polarization maintaining fiber Bragg grating; Single physical loop; Wavelength-switchable-tunable fiber laser
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2023.109695

•A dual-wavelength single longitudinal mode (SLM) narrow linewidth orthogonal single polarization fiber laser based on a parity-time (PT) symmetric system is proposed and demonstrated. The laser can achieve the tunable and switchable wavelength output.•The parity-time symmetric system comprises a single physical loop, which consists of two polarization controllers and a polarization beam splitter, implementing two coupled loops of the same length.•The proposed fiber laser has demonstrated a tunable range of 1549 nm to 1551 nm with stable linewidth and polarization state during tuning. The measured full width at half maximum linewidth for the left and right wavelength are less than 13.66 kHz and 11.89 kHz, respectively.•The degree of polarizations of left and right wavelength exceed 97%, a sum of azimuth is about 90°and demonstrate good stability in 20 min of test time. These demonstrate that the output laser has stable orthogonal single polarization characteristics.•The proposed laser exhibits superior characteristics, including dual-wavelength tunability and switchability, high stability, SLM operation, narrow linewidth, and orthogonal single polarization. These features make it highly promising for a range of applications, including long-distance multi-parameter optical fiber sensing and coherent lidar detection. A dual-wavelength narrow linewidth orthogonal single polarization fiber laser based on a parity-time (PT) symmetric system is proposed and demonstrated, which achieves the function of tunable and switchable wavelength, and single longitudinal mode (SLM) operation. The PT symmetric system composes of a single physical loop, which includes two polarization controllers (PCs) and a polarization beam splitter (PBS). By modulating PCs to match gain, loss and coupling coefficient, the switchable wavelength and stable SLM laser output have been achieved. Through stretching the polarization maintaining fiber Bragg grating (PM-FBG), the wavelength adjustment range from 1549 nm to 1551 nm is obtained. In the process of tuning, the full width at half maxima (FWHM) linewidths and polarization states at each wavelength have been measured and keep basically stable. The measured FWHM linewidths are less than 13.66 kHz and 11.89 kHz. Further, the stable orthogonal single polarization state has been realized. The degree of polarization (DOP) at each wavelength exceeds 97% and basically remains unchanged during 20 min.