<p>This study investigates ultrashort pulse propagation and supercontinuum (SC) generation in lead silicate photonic crystal fibers (PCFs) with near-zero normal and anomalous dispersion using the finite-difference time-domain (FDTD) method. A comparative analysis is performed using the split-step Fourier method for pump pulses of 20, 50, and 100 fs durations at 1550 nm with a peak power of 1 kW. The results demonstrate that a 20 fs pulse in the normal dispersion regime produces an SC spectrum spanning 800–2500 nm, achieving a broad and coherent output primarily driven by self-phase modulation and four-wave mixing. In contrast, an anomalous dispersion regime results in an SC spectrum extending from 1000 to 3000 nm, dominated by soliton fission and Raman-induced soliton self-frequency shift. The presence of two zero-dispersion wavelengths (1.2 and 1.9 μm) enhances dispersive wave generation, contributing to extended spectral broadening. The proposed PCF design ensures high nonlinearity <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10825_2025_2305_Article_IEq1.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="143" /> </InlineMediaObject> <EquationSource Format="TEX">$(\gamma ={415 \text{W}}^{-1}{\text{Km}}^{-1})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>γ</mi> <mo>=</mo> <msup> <mrow> <mn>415</mn> <mtext>W</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <msup> <mrow> <mtext>Km</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and low confinement loss making it suitable for broadband SC generation at low input power. This study provides a promising approach for compact and efficient ultra-broadband light sources with applications in telecommunications, imaging, and optical sensing.</p>

Supercontinuum generation dynamics in highly nonlinear photonic crystal fiber with normal and anomalous dispersion

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发表日期：

2025年5月2日

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Monika Goyal,
Sujata Vedi,
Manoj Mishra,
Mohit Sharma

摘要

This study investigates ultrashort pulse propagation and supercontinuum (SC) generation in lead silicate photonic crystal fibers (PCFs) with near-zero normal and anomalous dispersion using the finite-difference time-domain (FDTD) method. A comparative analysis is performed using the split-step Fourier method for pump pulses of 20, 50, and 100 fs durations at 1550 nm with a peak power of 1 kW. The results demonstrate that a 20 fs pulse in the normal dispersion regime produces an SC spectrum spanning 800–2500 nm, achieving a broad and coherent output primarily driven by self-phase modulation and four-wave mixing. In contrast, an anomalous dispersion regime results in an SC spectrum extending from 1000 to 3000 nm, dominated by soliton fission and Raman-induced soliton self-frequency shift. The presence of two zero-dispersion wavelengths (1.2 and 1.9 μm) enhances dispersive wave generation, contributing to extended spectral broadening. The proposed PCF design ensures high nonlinearity $(\gamma ={415 \text{W}}^{-1}{\text{Km}}^{-1})$ $(γ = {415 W}^{- 1} {Km}^{- 1})$ and low confinement loss making it suitable for broadband SC generation at low input power. This study provides a promising approach for compact and efficient ultra-broadband light sources with applications in telecommunications, imaging, and optical sensing.