Efficient 16 μm linearly-polarized single-frequency phosphate glass fiber laser

Based on the heavily Er3+/Yb3+ co-doped phosphate glass fiber (EYPF) with a larger emission cross-section, an efficient linearly-polarized single-frequency distributed Bragg reflector fiber laser at 1603 nm is demonstrated. By balancing the cavity length against the longitudinal mode spacing, a stable single-longitudinal-mode laser with more than 20 mW is generated from a 16-mm-long EYPF. The measured relative intensity noise of the fiber laser is less than –140 dB/Hz at frequencies of over 5 MHz. The signal-to-noise ratio is greater than 62 dB and the linewidth is less than 1.9 kHz, while the obtained polarization extinction ratio is higher than 25 dB. The L-band operating combined with the narrow linewidth and low noise characteristic makes this laser an ideal candidate for high-resolution molecular spectroscopy and coherent lidar applications.