Fig. 1. (a) Schematic of the experimental setup. DM, dichroic mirror; HR, high-reflection mirror; LD, laser diode. Insets: measured spectral transmission profiles of spectral filters. (b) Measured transmission loss (left-hand axis) and calculated second-order dispersion β₂ (right-hand axis) of the AR-HCF. Inset: SEM image of the fiber cross-section.

Fig. 2. (a) Average output power (left-hand axis) and pulse energy (right-hand axis) as a function of absorbed pump power. (b) Measured output spectra for the indicated pulse energies.

Fig. 3. (a) Oscilloscope trace of the output pulses. (b) RF spectrum with an RBW of 10 Hz and a span of 200 kHz at the fundamental frequency of 18.46 MHz. Inset: RF spectrum with 1 GHz span.

Fig. 4. (a) Measured output spectra of the MO for GDD values of +0.022 ps² (blue), –0.004 ps² (red) and –0.008 ps² (orange) at the maximum pulse energy. (b) Corresponding measured AC traces of the de-chirped pulses (solid curve) compared to the calculated AC traces of the TL pulses (dashed curve).

Fig. 5. Measured AC duration of the de-chirped pulses (red), calculated AC duration of the TL pulses (blue) and the corresponding ratio between the two (gray) as a function of increasing pulse energy.

Fig. 6. Schematic of the pulse compression setup utilizing the AR-HCF. OSA, optical spectrum analyzer; AC, autocorrelator.

Fig. 7. (a) Measured AC trace (solid red line) of the de-chirped pulse and the calculated AC trace of the TL pulse (dashed blue line) using the AR-HCF. (b) Measured AC duration of the de-chirped pulse as a function of pulse energy transmitted through the AR-HCF.

Fig. 8. (a) Output spectrum of the MO (blue) and after AR-HCF delivery (red). (b) M² (beam quality) measurement at maximum pulse energy. Inset: measured far-field beam intensity profile.