Fig. 1. Schematic of the all-fiber pulsewidth measurement setup based on IJ-FPGA.

Fig. 2. (a) Pulses of the fixed arm and the variable arm at different delay times τ, (b) the pulse envelope measured by a low-speed PD at the corresponding delay time τ, and (c) the normalized V_max data (blue dots) and fitting envelope (red line).

Fig. 3. Intensity envelope of the original pulse (red line) and the numerically simulated (τ, V_max) envelope (blue line) in (a) the fs regime and (b) the ps regime.

Fig. 4. (a) Experimental setup of the 1.06 µm ultrafast laser. WDM, wavelength-division multiplexer; PM-YSF, polarization-maintaining Yb-doped fiber; CFBG, chirped fiber Bragg grating. (b) and (d) Optical spectra. (c) and (e) AC trace with a commercial autocorrelator (blue line) and IJ-FPGA trace (red dots).

Fig. 5. (a) Experimental setup of the 1.5 µm ultrashort pulsed laser. OC, optical coupler. (b) and (d) Optical spectra of the measured ultrafast laser. (c) and (e) AC trace with a commercial autocorrelator (blue line) and IJ-FPGA trace (red dots).

Fig. 6. (a) Schematic of the 2.15 µm ultrafast fiber laser. TDF, Tm³⁺-doped double-clad fiber. (b) Optical spectrum. (c) IJ-FPGA trace (red dots) and fitting (red line).

Fig. 7. IJ-FPGA trace (red dots) and fitting envelope (blue line) with different input power (pulse energy).