Mode-locked erbium-doped fiber laser via evanescent field interaction with indium tin oxide

Abstract Light-matter interaction inside EDFL cavity was achieved by incorporating indium tin oxide onto D-shape fiber using electron-beam deposition technique. The D-shape fiber was fabricated using a homemade rotating wheel to expose evanescent field on the surface of single-mode optical fiber. The D-shape fiber sample possesses a remaining fiber diameter of 90 µm with 2 dB insertion loss. Our SA device successfully induced stable mode-locked at the operating wavelength of 1561.5 nm. Linear absorption by our SA was observed to be 2 dB at 1.55 µm region and saturable absorption was measured to be 4% with a saturable intensity of 40.32 MW/cm2. As a result, it was observed that the ITO-D-shape fiber generated pulses of as short as 1.13 ps with a stable repetition rate around 974.8 kHz as the pump power was adjusted within 104.62 mW to 187.04 mW. We confirmed stable pulses as the radio frequency spectrum analyzer displayed a fundamental frequency with high signal-to-noise ratio of 70 dB.