Ultra-short distributed Bragg reflector fiber laser for sensing applications.

We present an ultra-short distributed Bragg reflector fiber laser written in Er/Yb co-doped fiber. The entire laser is only 8.4 mm in length. The lasing threshold is less than 1 mW. The optical signal-to-noise ratio of the laser output is better than 70 dB. The laser emits two orthogonal polarization modes and generates a beat signal with signal-to-noise ratio of approximately 70 dB and 3-dB linewidth of approximately 3 kHz. The laser has longitude mode spacing comparable to the grating bandwidth. This obviates the possibility of mode hopping when the laser is subjected to any external perturbations.