Fig. 1. Experimental setup. Table-top Yb laser (1.36 mJ, 1 kHz repetition rate) composed of two output channels (“output 1” corresponding to 300 ps pulses, and “output 2” corresponding to 600 fs pulses) coupled into two different IC Kagome HC-PCFs.

Fig. 2. (a) SEM images of the cross section of the two IC fibers used. Transmission (shaded grey curves), loss (blue curves), and effective index of the core fundamental mode (black curve) spectra for (b) Fiber #A and (c) Fiber #B. Normal and anomalous dispersion regimes in different transmission bands identified by ND and AD, respectively.

Fig. 3. (a) Raman comb generated at the output of IC Fiber #A for a 300 ps laser pulse duration. Evolution of the 3 m long air-filled IC Fiber #A output spectrum. (Top) Output spectrum for input energy of 1.36 mJ. The input pulse is shown for comparison. (Right) Transmission coefficient versus input energy. (b) Rotational response of the AS2 line.

Fig. 4. (a) SC generated at the output of IC Fiber #B for a 600 fs laser pulse duration. Experimental evolution of the 3.8 m long air-filled IC Fiber #B output spectrum. (Top) Output spectrum for input energy of 840 μJ. The input pulse is shown for comparison. (Right) Transmission coefficient versus input energy. (b) Dispersed beam of the SC generated at the output of the IC Fiber #B.

Fig. 5. (a) Theoretical spectral evolution of the 20 cm long air-filled IC Fiber #B output spectrum. (Top) Output spectrum for input energy of 840 μJ. The input pulse is shown for comparison. (b) Output fiber theoretical spectral evolution with the input energy (100, 200, and 400 μJ) for a fiber length of 20 cm. (Bottom) Phase mismatch curve Δβ as a function of the idler/signal wavelengths (f2 and f3). (c) Theoretical temporal pulse profiles for two input energies: 20 μJ and 500 μJ.

Fig. 6. (a) Phase mismatch Δβ1n versus the mode number n. (b) Experimental spectral evolution with input power, up to 175 mW, of the THG at the output of a 30 cm long air-filled IC Fiber #B.