Conference Agenda

We demonstrate a high-beam-quality MMF amplifier achieved through input beam shaping. By controlling the amplitude and phase of both orthogonal polarization components at the input, we tailor the high-power output to a desired spatial profile, effectively compensating for the complex and nonlinear mode coupling within the MMF amplifier. This approach provides full control over both the spatial profile and polarization state of the amplified output. As a demonstration, we generate a Gaussian beam with M^2 = 1.09 and a polarization extinction ratio (PER) of 19.6 dB at an output power of 538 W.

Multimode optical solitons exhibit peculiar properties and holds potential for a large number of applications, from the next generation of high power lasers to the new spatially multiplexed communications systems. In this work, we theoretically study the impact of core refractive index distribution in a multimode fiber on the spatiotemporal dynamics and peculiar properties of multimode (MM) solitons. The characteristic MM soliton energy increases as the index distribution parameter (α) deviates from its optimal value of 2.08. Additionally, one can induce the flow of energy in a direction opposite to the conventional MM soliton condensation process with suitable value of the index distribution parameter (α).

Supercontinuum generation in all-normal-dispersion fibers has mainly been explored with femtosecond pumping. Here, we demonstrate broadband SC generation in the long picosecond regime by pumping a highly birefringent all-normal-dispersion photonic crystal fiber at 1064 nm. Spectral broadening arises from polarization modulation instability (PMI) combined with stimulated Raman scattering (SRS), producing octave-spanning spectra from 600 nm to 1650 nm.

Although it is generally believed that scalar modulation instability

in fibres is governed by interaction between nonlinearity and only even orders

of dispersion (β₂,β₄), we show here that, under pulsed excitation, modulation

instability can still be observed with only third-order dispersion β₃. This be

havior is attributed to an effective second-order β₂ dispersion induced by the

interaction of β₃ and self-phase modulation.

We study sub-micron tapered optical fibers as a promising platform for tunable biphotons generated by spontaneous four-wave mixing (SFWM). Tuning of the sidebands is done by adjusting the environmental pressure. Seeding on the idler side, the variations of taper diameter lead to comb-like spectrum in the signal region.

We experimentally and theoretically investigated seeded FWM yielding a comb-like structure in the generated spectrum, revealing the bell-shape structure of the fabricated sub-micrometer tapered fiber. This is a non-destructive way to characterize sub-micrometer tapers.