In this paper, we propose a new, to the best of our knowledge, saturable absorber (SA) based on sodium carbonate (N a 2 C O 3) for producing an ultrafast mode-locked stretched pulse in a passively erbium-doped fiber laser at near-zero dispersion. The solid film of a N a 2 C O 3-SA was fabricated by the drop-casting method using polyvinyl alcohol as a host polymer. The modulation depth of the proposed SA, which was measured by a balanced twin detector technique, was 2.3% with saturation intensity of 181M W/c m 2. The mode-locking operation of the EDFL-based N a 2 C O 3-SA was observed at a pump power of 117mW. A stable stretched pulse was generated by using the proposed N a 2 C O 3-SA. The laser can generate pulses with a repetition rate and duration of 1.87MHz and 820fs, respectively, within a bandwidth of 6.6nm. The single pulse energy reaches up to 5nJ, which is equivalent to the average output power of 9.3mW. Finally, to the best of our knowledge, this is the first report on using the N a 2 C O 3-SA for generating a stretched-pulse mode-locked fiber laser.