Low-loss waveguides written with a femtosecond laser for flexible interconnection in a planar light-wave circuit

Abstract

We describe a low-loss single-mode waveguide in planar light-wave circuit (PLC) glass doped with boron and phosphorus, which is more difficult to write than pure-silica glass. The written waveguide has a rectangular core, a symmetric near-field pattern, and a propagation loss of 0.35 dB/cm. The loss that originates from the mode-field mismatch between the mode-field diameters of the written and the PLC waveguides is less than 0.1 dB/point. In addition, we successfully connected PLC waveguides with a 500-microm-long waveguide written with a laser. The laser-written waveguide can flexibly connect PLC waveguides with a low coupling loss.

Ultrafast-laser-inscribed 3D integrated photonics: challenges and emerging applications

“…Also a deformable mirror (DM) can be used instead of an SLM in order to astigmatically shape the laser focal spot [73]. Another popular method to obtain circular mode fields is to use the multiscan technique [58,74]. Using low-NA focusing and by inscribing multiple elliptical modifications next to one another, a rectangular-or square-shaped waveguide can be created.…”

“…Low loss enables the integration of many components, such as splitters, on a single chip whilst still maintaining high throughput. Using optimised inscription parameters, propagation losses as low as 0.1 dB/cm at a wavelength of 1550 nm have been reported in fused silica for waveguides fabricated in the athermal regime [57,58]. Thermal annealing can be applied to reduce propagation losses by removing transient defects.…”

Femtosecond laser microstructuring: an enabling tool for optofluidic lab‐on‐chips

“…This arrangement also creates waveguides with symmetric cross section, but has the disadvantage of wasting most of the laser power impinging on the slit. Alternative approaches for controlling the waveguide cross section are multiscan writing [61] and spatial beam shaping with a deformable mirror [62]. The asymmetry problem is naturally overcome in the high frequency writing regime, since isotropic heat diffusion leads to a symmetric waveguide cross section [63].…”

Compact Cr:ZnS channel waveguide laser operating at 2333 nm

“…This energy transfer may result in a localized refractive index change to the material which can be exploited for the fabrication of waveguide structures. Through careful control of the inscription parameters, waveguides of arbitrary cross-section can be created by translating the target substrate through the focus [19].…”