A pulsewidth measurement technology based on carbon-nanotube saturable absorber

We demonstrate a proof-of-concept saturable absorption based pulsewidth measurement (SAPM) by exploring the intensity dependent nonlinear transmission (i.e., saturable absorption) of low-dimensional material (LDM) carbon nanotubes. A minimum pulse energy of 75 fJ is experimentally detected with an average-power-peak-power product (Pav⋅ Ppk) of 5.44×10−7 W2 near 1550 nm. A minimum detectable pulse energy of 10 fJ with a Pav⋅ Ppk of 1.3×10−9 W2 is estimated with further optimization. The nanometer-level thickness and femtosecond-level decay time of LDMs allow ultrafast light interaction on a very small footprint, which potentially supports chip-scale characterization of ultrafast pulses with minimum distortion.