Conference Agenda

We present the phase masking concept as a way for improving optical imaging system performance. We explore different applications of the use of this concept for providing tolerance to the presence of aberrations. We focus our attention on its use as a fundamental part of Wavefront Coding systems employed to obtain high resolution images; and as a key part in the design of ophthalmic elements for refractive error corrections. We compare different phase masks present in the literature, showing their goals and drawbacks. Besides we show a new methodology for studying system performance based on the analysis of the system’s point spread function, including the postprocessing step in the case of wavefront coding. Numerical and experimental data will be included in the discussion and analysis of the phase masking technique.

While microfluidics still relies heavily on polydimethylsiloxane (PDMS) as a benchmark material, alternative elastomers such as Flexdym are attracting increasing interest due to their processing versatility and potential for fast device fabrication. In parallel, femtosecond pulsed laser ablation (fs PLA) offers precise surface micromachining with minimal thermal damage, being especially advantageous for polymeric substrates. In this work, fs PLA was applied to Flexdym to evaluate laser-induced modifications on its surface properties. The ablation threshold of the material was determined. Micrometric surface features were generated under controlled irradiation conditions. These laser-ablated modifications led to measurable changes in the contact angle with respect to non-processed Flexdym, demonstrating that femtosecond laser processing is a suitable strategy to control the wettability and surface behaviour of this flexible material.

Femtosecond laser-based fabrication offers high design flexibility for integrating optical and microfluidic structures in glass substrates. This work presents a comprehensive manufacturing process for optofluidic refractive index sensors, combining Femtosecond Laser Direct Writing (FLDW) for waveguide inscription with Selective Laser-induced Etching (SLE) for fluidic channel realization. Sequential laser processing on a single system ensures precise alignment between waveguides and fluidic interfaces. The process chain, including laser writing, wet etching, and sealing, is demonstrated through the fabrication of Mach-Zehnder interferometer (MZI) evanescent field sensors. Process validation confirmed precise control of the waveguide–fluid interface distance. The fabricated devices achieved a minimum detectable refractive index difference of ∆n = 0.073 relative to deionized water, confirming the suitability of the combined FLDW-SLE process for integrated optofluidic sensing platforms.

Integrated photonic platforms are increasingly relevant for sensing applications requiring efficient light–fluid interaction. In this work, we present a crystalline optofluidic device based on surface depressed-index cladding waveguides fabricated in undoped YAG crystal by femtosecond laser direct writing. The waveguide geometry is tailored through vertical tapering to enhance light-surface interaction. Micro-grooves are inscribed on the crystal surface, perpendicular to the propagation direction, enabling spatially controlled light extraction at the solid–fluid interface. The platform is validated through fluorescence excitation in a PDMS microfluidic channel placed on top of the crystal surface, demonstrating its potential for optofluidic sensing applications.

Localized pH monitoring at the micro/nanoscale is essential for understanding dynamic biochemical, environmental, and interfacial processes, yet existing pH microsensors often suffer from invasiveness, toxicity, poor scalability, and limited integration into compact photonic platforms. This work presents a one-step femtosecond laser-assisted maskless fabrication approach for developing quasi 3D-patterned chitosan-based micro/nano pH sensors. During laser patterning, chitosan acts simultaneously as a biocompatible solid-state matrix and as a carbon/nitrogen precursor, enabling in situ formation of nitrogen-doped carbon quantum dots (NCQDs) along the laser-irradiated region. The resulting quasi-3D fluorescent micro/nanostructures exhibit excitation-dependent emission and pH-responsive fluorescence lifetime behaviour. Structural, morphological, chemical, and optical characterizations using SEM, TEM, AFM, XRD, FTIR, Raman, XPS, CLSM, and FLIM confirm localized NCQD formation, nitrogen/oxygen functionalization, and stable fluorescence in the patterned regions. The sensor shows a systematic fluorescence lifetime shift from acidic to basic conditions, with lifetime increasing from approximately 2.14 ns to 2.94 ns as pH changes from 3.01 to 11.94. This biopolymer-based, maskless optical fabrication strategy offers a scalable route toward solid-state, miniaturized, and biocompatible pH sensors for lab-on-chip, biosensing, and nanophotonic applications.