Flat Supercontinuum Generation within the Telecommunication Wave Bands in a Photonic Crystal Fiber with Central Holes

Flat supercontinuum in the telecommunication wave bands of E+S+C is generated by coupling a train of femtosecond pulses generated by a mode-locked Ti:sapphire laser into the fundameutal mode of a photonic crystal fiber with central holes fabricated in our lab. The pulse experiences the anomalous dispersion regime,and the soliton dynamic effect plays an important role in supercontinuum generation.The output spectrum in the wavelength range of 1360 1565nm does not include significant ripples due to higher pump peak power,and the normalized intensity shows less fluctuation.

Widely Wavelength-Tunable Blue-Shifted Dispersive Waves for Broadband Visible Wavelength Generation in a Photonic Crystal Fiber Cladding

Blue-shifted dispersive waves(DWs)are efficiently generated from the red-shifted solitons by coupling the 120 fs pulses into the fundamental mode of the multi-knots of a photonic crystal fiber cladding.When the femtosecond pulses at the wavelength of 825 nm and the average power of 300 mW are coupled into knots 1–3,the conversion efficiencyηDW of 32%and bandwidth BDW of 50 nm are obtained.The ultrashort pulses generated by the DWs can be tunable over the whole visible wavelength by adjusting the wavelengths of the pump pulses coupled into different knots.It can be believed that this widely wavelength-tunable ultrashort visible pulse source has important applications in ultrafast photonics and resonant Raman scattering.

Ultraviolet Continuum Generation in the Fundamental Mode of Photonic Crystal Fibers

The ultraviolet continuum generation in the fundamental mode of photonic crystal fibers designed and fabricated in our lab are experimentally demonstrated.When the pump works in the normal dispersion regions of 780 nm and 830 nm,and the average powers increase from 100 to 500 m W,anti-Stokes signals can be efficiently generated based on the phase-matched degenerate four-wave mixing.The cross-phase modulation between the pump and the generated anti-Stokes signals can effectively extend the continuum into the ultraviolet wavelength range.This can provide an efficient light source for ultraviolet photonics and spectroscopy.

Modal cutoff in rare-earth-doped photonic crystal fibers with multi-layer air-holes missing in the core

The various mode effective indices of the doped photonic crystal fibers (PCFs) are compared, the mode field distributions of the fundamental mode and the second-order mode are analyzed, and the single-mode condition is presented. The mode effective indices of large-core doped PCFs with different core indices and structure parameters are simulated by the finite element method (FEM). The relations of the core index with the fiber structure parameters of pitch, hole-to-pitch ratio and core diameter are obtained for single-mode propagation. In the design and fabrication of the doped PCF, we can adjust the core index and fiber structure parameters to achieve large mode area and single-mode propagation.