arXiv subjects

H. L. Fragnito

Publications and source records attributed to H. L. Fragnito.

4 recordsLinked to original sources

arXiv2026

Spectrally flat and broadband doublepumped fiber optical parametric amplifiers

We study theoretically and experimentally spectrally flat and broadband double-pumped fiber-optical parametric amplifiers (2P-FOPAs). Closed formulas are derived for the gain ripple in 2P-FOPAs as a function of the pump wavelength separation and power, and the fiber non-linearity and fourth order dispersion coefficients. The impact of longitudinal random variations of the zero dispersion wavelength $λ_0$ on the gain flatness is investigated. Our theoretical findings are substantiated with experiments using conventional dispersion shifted fibers and highly nonlinear fibers (HNLFs). By using a HNLF having a low variation of $λ_0$ we demonstrate high gain and flat spectrum ($25 \pm 1.5\text{ dB}$) over $115\text{ nm}$.

physics.optics↗

arXiv2026

Q penalties due to pump phase modulation and pump RIN in fiber optic parametric amplifiers with non-uniform dispersion

We present an experimental and numerical investigation of the quality factor degradation ($ΔQ$) due to pump phase modulation and pump relative intensity noise (RIN) in single- and double-pumped fiber optical parametric amplifiers (FOPAs). These penalties are investigated in FOPAs constructed with fibers having constant and randomly varying zero-dispersion wavelength ($λ_0$) along the fiber. We show that pump phase modulation in uniform fibers (constant $λ_0$) produces large $Q$ penalties, while in fibers with variations of $λ_0$, these penalties can be strongly reduced in both single- and double-pumped FOPAs. We also show that $Q$ penalties due to pump phase modulation tend to disappear in FOPAs made with very short fibers ($L<0.1~\mathrm{km}$) and very low dispersion slope $ S_0 < 0.002~ \mathrm{ps}\, \mathrm{nm}^{-2}\, \mathrm{km}^{-1}. $ The $Q$ penalties due to pump RIN, which for typical FOPA parameters are much smaller than those due to pump phase modulation, are also reduced in non-uniform fibers (varying $λ_0$), but do not depend on fiber length nor on fiber dispersion slope.

physics.optics↗

arXiv2008

Multi-wavelength source at ITU-T grid based on ultra-flattened dispersion photonic crystal fibers

We report on the development of a multi-wavelength source locked to the ITU-T grid at 100 GHz spacing and based on ultra-flattened dispersion photonic crystal fibers. The ITU-T grid frequencies are generated by taking advantage of multiple four-wave mixing processes. We experimentally obtained 250 products spanning over 200nm by launching 03 strong pump signals. Simulations based on Split-Step Fourier Method have been carried out in order to investigate and improve the performance of this nonlinear optical device.

physics.optics↗

arXiv2008

Coherent Control of Ultra-High Frequency Acoustic Resonances in Photonic Crystal Fibers

Ultra-high frequency acoustic resonances ($\backsim$2 GHz) trapped within the glass core ($\backsim$1 $μ$m diameter) of a photonic crystal fiber are selectively excited through electrostriction using laser pulses of duration 100 ps and energy 500 pJ. Using precisely timed sequences of such driving pulses, we achieve coherent control of the acoustic resonances by constructive or destructive interference, demonstrating both enhancement and suppression of the vibrations. A sequence of 27 resonantly-timed pulses provides a 100-fold increase in the amplitude of the vibrational mode. The results are explained and interpreted using a semi-analytical theory, and supported by precise numerical simulations of the complex light-matter interaction.

physics.optics↗