All-optical mode and wavelength converter based on parametric processes in a three-mode fiber

Spatially multiplexed picosecond pulse-train generations through simultaneous intra-modal four wave mixing and inter-modal cross-phase modulation

“…The output temporal profiles are broadened and tilted when the input signal wavelength is unphase-matched with the central wavelength of the beating. Once again, these results underline the high sensitivity of the inter-modal nonlinear interactions in FMFs with respect to the phase matching conditions, as already highlighted in several previous works [7][8][9][10][11][12] and which could be seen as a strong limitation for practical applications without a specific fiber design [46][47][48].…”

Shape-preserving and unidirectional frequency conversion by four-wave mixing

“…(14), the terms describing crossphase modulation contain factors of 2/3, representing the case of orthogonally polarized fields in an isotropic material such as fused silica. This factor may be different if one considers the BS process using higher-order spatial modes [30,31], or in a material with an anisotropic Kerr nonlinearity such as crystalline silicon [43]. We stress, however, that what follows does not depend on the value of this prefactor.…”

“…Noteworthy, in the cross-polarized configuration, the wavenumber mismatches of the undesired BS process contain one term inversely proportional to the beat length L B , and another term proportional to the difference in inverse group velocity ∆β 1 . For standard birefringent fibers with beat lengths on the order of 1-10 mm [40], the first term is typically orders of magnitudes larger than the second term for which ∆β 1 ≈ 1 ps/m (and ∆ω ≈ 5-20 THz) [31,36]. This is also the case in integrated birefringent waveguides, where the beat length can readily be made smaller than hundreds of micrometer at optical wavelengths [41,42].…”

“…In this work, we seek solutions to these challenges by investigating a scheme for BS where the two pump pulses are polarized on orthogonal axes of a nonlinear birefringent waveguide, or as recently demonstrated, propagate in different spatial modes of a higher-order mode fiber [30,31]. We show that this configuration allows highly unidirectional frequency conversion with the conversion direction being controlled by the polarization of the input signal.…”

Intermodal Bragg-Scattering Four Wave Mixing in Silicon Waveguides

“…In this work, we demonstrate the uni-directionality of the FWM BS process by exploiting the spatial modes of a multi-mode silicon waveguide. The extra degree of freedom given by the capability to carefully excite and control higher order modes in multi-mode nonlinear waveguides offers more options to fulfill the required phase matching [12], [13], [14], [15], [16]. Thus, multiple discrete spectral bands can be simultaneously phase matched, leading to simple scalable and controllable discrete wavelength converters that can be largely detuned from the pump(s) wavelengths by exciting phase matched and dispersion tailored modes of a single multi-mode nonlinear waveguide.…”