Recent advancements in photonic-electronic integration push towards denser multichannel fiber to silicon photonic chip coupling solutions. However, current packaging schemes based on suitably polished fiber arrays do not provide sufficient scalability. Alternatively, lithographically-patterned fused silica glass interposers have been proposed, allowing for the integration of fanout waveguides between a dense array of on-chip silicon waveguides and a cleaved fiber ribbon. In this paper, we propose the use of femtosecond laser inscription for the fabrication of the fused silica glass interposer, allowing for a monolithic integration of waveguides and V-grooves for fiber alignment. The waveguides obtained by Femtosecond Laser Direct Writing (FLDW) have a propagation loss of 0.88 dB/cm at 1550 nm. The mode-field diameter is 12.8 ± 0.4 µm, allowing for a coupling loss of 1.24 ± 0.32 dB when coupling to a standard single mode optical fiber, passively aligned to the fused silica waveguide by insertion in a V-groove created by Femtosecond Laser Irradiation followed by Chemical Etching (FLICE). The average surface roughness of the etched waveguide facet is 160 ± 5 nm. Scattering loss when coupling to fiber is reduced by use of an index-matching adhesive for fiber fixation. A polished out-of-plane coupling mirror at an angle of 41.5 • injects the light into standard grating couplers, providing a quasi-planar fiber-to-chip package. The excess loss of the proposed solution is limited to 2 dB per interface, including mirror, waveguide and fiber coupling losses. Using the currently optimized laser parameters, the time required to expose a single V-groove/waveguide combination is around one minute.

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LC beam steering devices are realized using the combination of liquid crystal and polymer micro grating structures. The micro gratings are fabricated by combining two major techniques: laser ablation for a master mold and soft lithography for replicas with the desired optical materials. The LC components demonstrate effective beam deflections with a steering angle of 2.6° for both polarized monochromatic light (deflection efficiency >40%) and unpolarized white light beam (deflection efficiency >30%).

Femtosecond laser inscription allows straightforward manufacturing of glass planar lightwave circuits such as waveguides, interferometers, directional couplers, resonators and more complex structures. Fiber alignment structures are needed to facilitate communication with the glass planar lightwave circuit. In this study, a technique is described to create optical waveguides and alignment structures in the same laser exposure step. Using an industrial ytterbium-doped 1030 nm fiber laser pulses of 400 fs were focused into glass with a 0.4 NA objective causing permanent alteration of the material. Depending on laser parameters this modification allows direct writing of waveguides or the creation of channels after exposing the irradiated volumes to an etchant such as KOH. Writing of channels and waveguides with different laser powers, frequencies, polarisations, stage translation speeds and scan densities were investigated in fused silica and borosilicate glass. Waveguides with controlled dimensions were created, as well as etched U-grooves with a diameter of 126 µm and a sidewall roughness R a of 255 nm. Cut back measurements were performed giving a waveguide propagation loss of 1.1 dB/cm in borosilicate glass. A coupling loss of 0.7 dB was measured for a transition between the waveguide and standard single mode fiber at 1550 nm, using index matching liquid. The described technique eliminates active alignment requirements and is useful for many applications such as microfluidic sensing, PLCs, fan-out connectors for multicore fibers and quantum optical networks.