Conference Agenda

We report the use of ultrafast spatial shaping for the post-compression of femtosecond pulses and the generation of intense attosecond pulses. In our laboratory, the use of LG0,3 beams allowed peak power scaling into the multi-gigawatt regime to create a compact laser driver to obtain XUV light with orbital angular momentum through high-order harmonic generation. We also study the spatial properties of high-order harmonics driven by a hollow Gaussian beam, consisting of a ring-shaped profile with no spatial phase variation.

We demonstrate broadband tunable generation of OAM modes in a ring-core fiber via nonlinear mode coupling. OAM states with controllable topological charge and wavelength are generated over a wide spectral range of 1250–2200 nm by systematically optimizing the injected mode and input power. High purity and power are achieved for modes particularly in the range 1640–2200 nm.

In this work, we present a comprehensive theoretical analysis of orbital angular momentum mode propagation within twisted, tapered, ring-core fibers. By generalizing the coupled-mode approach through transformation optics, we map the complex geometry of the non-uniform twisted fiber onto an equivalent straight fiber with anisotropic constitutive parameters. Crucially, we demonstrate that twist-induced modifications to the magnetic permeability introduce self-coupling terms that are equally significant to those arising from permittivity perturbations. We establish the explicit selection rules governing phase-matching and demonstrate how precise control over the twist pitch enables tunable modal power transfer.

We present a compact and efficient realization of Multi-Plane Light Conversion (MPLC) for full vectorial light modulation, enabling control over polarization, phase, and amplitude. Conventional MPLC implementations based on phase-only modulation suffer from losses and limited polarization control, while metasurface-based solutions require complex nanofabrication processes. Our approach employs laser-written birefringent waveplates in silica slides, each with fixed retardance and a spatially varying optical axis orientation. The structures are fabricated using direct laser writing of nanogratings in silica, achieving ~90% transmission and ~1–2 µm spatial resolution. We demonstrate high-dimensional unitary transformations, polarization-controlled spatial modes transformations, and high-dimensional demultiplexing at the telecom wavelength. This cleanroom-free platform shows strong potential for high-dimensional quantum processing, optical communication, and beam shaping, with future prospects for extending modulation into the frequency domain.

Non-homogeneously polarized optical beams, the so-called vector beams, have been extensively studied recently for a variety of applications such as high-resolution lithography. Plasmonic lithography, e.g., is a promising candidate for overcoming the diffraction limit of light and enabling nano fabrication at lower costs which is highly affected by the polarization distribution of the excitation beam. Radially polarized beam is the most efficient light beam for homogeneous excitation of propagating surface plasmons. A combination of vectorial diffraction theory and scalar Fourier optics allows us to simulate an arbitrary array of tightly focused radially polarized beams. These well separated spots are characterized experimentally for their uniformity and quality in the radial and longitudinal polarization components by a combined method of phase retrieval and stokes parameter analysis.