Switchable and tunable multiwavelength erbium-doped fiber laser with fiber Bragg gratings and photonic crystal fiber

We propose and report on a novel multiwavelength-switchable-tunable erbium-doped fiber laser with excellent stability and uniformity based on four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber. By adjusting the attenuators, the single, dual, or triple wavelengths can be lasing simultaneously. Under the influence of the FWM, the spectrum is stabilized and the uniformity is less than 0.6 dB.

Erbium-Doped fiber (EDF) lasers emitting multiple wavelengths simultaneously have attracted considerable interest. To overcome the limitation that EDF is an primarily homogeneous gain-broadening medium at room temperature, various approaches have been proposed [1]– [5]. Fig. 1. Experimental setup for a multiwavelength-switchable-tunable EDF laser. The most straightforward method is to use an independent gain segment for each wavelength, where EDF lasers may be achieved by pumping with appropriate wavelength multiplexing and demultiplexing [4]. However, most of the approaches lead to inhomogeneity in a single EDF, when various elements such as acoustooptic frequency shifters [6], comb or interferometer filters [7], and Sagnac loop reflectors are introduced [2]. To improve the stability of the multiwavelength EDF lasers, many different techniques of reducing mode competition, such as cooling the EDF at 77 K [8], introducing active overlapping linear cavities [9], and using the polarization hole burning principle [5] have been proposed.