Cover story: Yin SY, Guo Q, Liu SR et al. Threedimensional multichannel waveguide grating filters. Opto-Electron Sci 3, 240003 (2024).

The perception of multi-dimensional information is essential for extracting various types of data within intricate physical environments. To improve the spatial integration and in-situ signal decoupling abilities of multi-dimensional sensors, Si-Yu Yin et al. have created a multi-channel spatially integrated filter that employs femtosecond laser direct writing technology. This innovative device comprises a compact, integrated multi-channel waveguide grating featuring distinct periods. Each channel's waveguide grating is responsive to changes in the environment, leading to corresponding variations in the center wavelength of the reflected spectrum.

The arrangement of channels in parallel within the device effectively mitigates the occurrence of multiple reflections of optical signals among gratings with differing periods. As a result, this configuration significantly reduces crosstalk among optical signals across various wavelength bands. The technology facilitates the dense integration of waveguide array gratings, which can accommodate hundreds of channels, thereby enabling parallel in-situ sensing and multi-parameter decoupling for a range of factors, including temperature, deformation, stress, and vibration, ultimately allowing for real-time sensing of multi-dimensional information. Moreover, this methodology demonstrates considerable potential for applications in multi-channel network information transmission and the development of fiber-to-home (FTTH) infrastructure.