Fig. 1. SEM images of all-solid soft glass ANDi PCFs. (a) NL21 series: core and hexagonal lattice (light color) made of F2 glass, lattice inclusions and lattice surrounding made of NC21A glass. (b) NL38 series: SF6 in the core and lattice, F2 in the inclusions and the surrounding tube.

Fig. 2. Dispersion profiles and effective mode areas obtained in numerical simulations for the all-solid glass ANDi PCFs: (a), (b) NL21 series; (c), (d) NL38 series; (e), (f) UV710+PBG08 fibers.

Fig. 3. Sequence of physical processes broadening the ultra-short laser pulse in an ANDi fiber. (a) Evolution of the spectrum along the entire nonlinear fiber length. (b)–(d) Numerical spectrograms.

Fig. 4. (a) Measured chromatic dispersion profiles of the fabricated fibers, (b) dispersion profile (measured and theoretical) and the wavelength dependence of the effective mode area of the B1 fiber, and (c) SEM images of this particular fiber.

Fig. 5. (a) SC spectra recorded for the ANDi fibers listed in Table 3, measured under pumping with 70 fs centered at 1550 nm, and (b) broadest recorded spectrum in the NL21B1 fiber, its numerical reconstruction with a GNLSE model and measured pump laser spectrum [54].

Fig. 6. SC spectra measured in the all-solid soft glass ANDi PCFs under 2160 nm femtosecond pumping. (a) NL21C2, (b) NL21C4, (c) NL38A2, and (d) NL38A4 [35].

Fig. 7. (a) Calculated effective mode area of the PCFs. (b) Theoretical (solid traces) and measured (dotted traces) dispersion profiles of the PCFs [35].

Fig. 8. Reconstruction of experimental results with numerical simulations: (a) NL21C2 fiber, (b) NL38A2 [35].

Fig. 9. Results of interference measurements of SC spectra and profiles of spectral degree of coherence: (a) anomalous dispersion-pumped PCF, coupled pump pulse energy Ein=2  nJ; (b) anomalous dispersion-pumped PCF, Ein=5  nJ; (c) ANDi PCF, Ein=2  nJ; and (d) ADNi PCF, Ein=5  nJ [78].

Fig. 10. SNR and the ensembles of DFT single-shot spectra with the averaged spectrum from an OSA before the stretching fiber for the investigated soft glass fibers: (a) NL21 fiber (ANDi) and (b) NL24 fiber (anomalous dispersion) [78].

Fig. 11. Spectral correlation maps obtained from DFT measurement data. (a) Typical features of SPM, SF, and calculated location of the dispersive wave (DSW) are indicated for the soliton-based SC. (b), (d) ANDi SC correlation is shown indicating formation of pump-seeded Raman components, first at Stokes-shifted wavelengths (350 mW of average pump power), followed by (c), (e) anti-Stokes-shifted wavelengths (390 mW of average pump power). SRS, stimulated Raman scattering. (f) Spectral correlation of the pump laser is shown in the bottom right [78].

Fig. 12. Numerically obtained mode field distributions. (a) Fundamental mode in the core. (b)–(d) Typical higher order modes in the photonic cladding of the NL21 type ANDi fiber [77,78].

Fig. 13. SC spectra obtained from numerical simulations using modeling (a) scalar GNLSE and (b) two coupled modes (vector) GNLSE. 500-shot realization with one photon per mode noise shown at each plot. In-coupled pump pulse energies shown in each plot [78].

Fig. 14. Spectral correlation maps calculated for the ANDi SC using (a) scalar GNLSE and (b) vector (two coupled modes) GNLSE [78].

Fig. 15. (a) Design of the core nanostructure, (b) theoretical distribution of the refractive index in the core, (c) stacked preform of fiber core, and (d) core preform drawn at a fiber drawing tower. Typical SEM images of (e) final nanostructured core fiber-core area and (f) detail of the core nanostructure [93].

Fig. 16. (a) Chromatic dispersion estimated from the design of the nanostructured core fibers based on numerical simulations. (b) Measured dispersion profiles of the fabricated fibers. (c) Spatial and spectral profile of the effective refractive index in the nanostructured core (dependence on the normalized diameter). (d) Chromatic dispersion profiles calculated for the fibers with different core diameters for an optimized material dispersion at the core nanostructure level [93].