Fig. 1. Experimental setup. GP, Glan prism; BS, non-polarizing beam splitter; λ/2, half-wave plate; PWM, power meter; FPC, fiber patch cord; ONF, optical nanofiber; OSA, optical spectrum analyzer; MO1 and MO2, microscope objectives; Spi, spectrum number i; RS, Rayleigh scattering signal measured by the spectrometer.

Fig. 2. (a–b) Experimental spectra and (c–d) results of numerical simulations at the input (Sp1, orange curve) and at the output (Sp6, black curve) of the fiber system, at the input of the transition 1 (Sp2, blue curve), 1 cm before the input of the ONF (Sp3, green curve), at the input of the nanofiber (Sp4, red curve), and at the end of the nanofiber (Sp5, cyan curve). Spectra in (b) and (d) are vertically shifted for clarity. DW, dispersive wave.

Fig. 3. (a) Group velocity dispersion β₂ versus wavelength for a fiber taper diameter of 690 nm. (b) Zero dispersion wavelengths (ZDWs) λ₀₁ (black) and λ₀₂ (red) as a function of fiber diameter. The vertical dashed blue line shows the fiber diameter D = 790 nm. (c) Phase-matching condition (Eq. (2)) for dispersive wave generation versus wavelength.

Fig. 4. Experimental spectra. Top spectrum: OSA measurement at the end of the fiber system. Bottom spectra: RS measurements along the ONF every 2 mm from z = 0 mm to z = 20 mm. 3ASRO, third anti-Stokes Raman order. Spectra are vertically shifted for clarity.