Dual-wavelength DFB fiber laser based on a chirped structure and the equivalent phase shift method

A chirped phase-shifted structure is demonstrated for compact multiwavelength distributed feedback (DFB) fiber laser at room temperature for the first time. The chirped structure provides separated resonance cavities and then the stable multiwavelength operation. The equivalent phase shift method is demonstrated to realize the desired chirp and phase shifts simply and flexibly. A 44-pm-spaced dual-wavelength DFB fiber laser is then achieved experimentally, which is the narrowest spacing ever reported for a compact multiwavelength fiber laser