Nanosecond Mode-Locked Erbium Doped Fiber Laser Based on Few Layer Bismuth Telluride Ultra Thin Film Saturable Absorber

In this work, we obtained a nanosecond modelocked fiber laser that works with a pulse width of 552 - 1050 ns, and a repetition rate of 0.500 - 0.950 MHz repetition rate in 1.55 μm region. The highest output power, peak power, pulse energy and peak laser efficiency were 3.5 mW, 6.6 mW, 6.9093 nJ, and 0.9512%, respectively, with total cavity length of 354.5 m, total dispersion -7.5018 pS2, and group velocity dispersion -21.1618 ps
²
/km, at bidirectional pump power of 365.4 mW. The threshold pump power for this length was 76.9 mW. The results show that the saturable absorber derived from
$\mathbf{Bi}_{2}\mathbf{Te}_{3}$
is capable of producing nanosecond mode locked fiber laser for possible applications that require high pulse energy and medium output power.