Bài báo khoa học

We numerically calculated multi-octave spanning supercontinuum generation (SCG) in two proposed As2Se3 photonic crystal fibers (PCFs) with low input peak powers and highly coherent characteristics with the effects of vacuum noise and pulse-to-pulse relative intensity noise. The first PCF with a lattice constant (Λ) of 1.5 µm and core diameter (dcore) of 5.48 µm has the flat all-normal dispersion in the wavelength range of 2–10 µm. For the input peak power of 5 kW, this fiber generates the all-normal dispersion SCG with a spectral bandwidth of 1.85–5.7 µm with pump wavelength at 3.5 µm, and two octave-spanning of 1.9–7.6 µm with pump wavelength at 5.5 µm. The second PCF with Λ of 1.52 µm and dcore of 7.3 µm has flat dispersion and two zero-dispersion wavelengths at 4.3 µm and 7.8 µm. By launching the input peak power of 7.5 kW, and pump wavelength at 3.5 µm, the second PCF generates the broad SCG with a spectral bandwidth of 2–10 µm. The SCG in two proposed PCFs has high coherence due to the effects of vacuum noise. However, the results of our works point out that pulse-to-pulse relative intensity noise significantly decreases the coherence. The amount of coherence reduction depends on the pulse duration and the physical mechanism for spectral broadening in which a part of the supercontinuum spectrum induced by optical wave breaking and dispersive wave experiences a remarkable reduction of coherence due to the effects of pulse-to-pulse relative intensity noise.