Roadmap on multimode light shaping

Our ability to generate new distributions of light has been remarkably enhanced in recent years. At the most fundamental level, these light patterns are obtained by ingeniously combining different electromagnetic modes. Interestingly, the modal superposition occurs in the spatial, temporal as well as spatio-temporal domain. This generalized concept of structured light is being applied across the entire spectrum of optics: generating classical and quantum states of light, harnessing linear and nonlinear light-matter interactions, and advancing applications in microscopy, spectroscopy, holography, communication, and synchronization. This Roadmap highlights the common roots of these different techniques and thus establishes links between research areas that complement each other seamlessly. We provide an overview of all these areas, their backgrounds, current research, and future developments. We highlight the power of multimodal light manipulation and want to inspire new eclectic approaches in this vibrant research community.

Fiber-to-waveguide coupling based on plasmonic devices

Due to the large difference in mode size and effective-index mismatch between the optical fiber and the waveguides on the photonic integrated circuits, it is a big challenge to efficiently couple light into thin semiconductor waveguides. In this paper, a taper plasmonic coupler is presented to couple fiber light into an Si waveguide. The taper plasmonic coupler structure is optimized, and the alignment tolerance of the gap, the lateral offset and the vertical offset between coupler and Si waveguide are studied. Numerical simulation shows that the coupler changes the single mode fiber light to multimode light at its input port section, while at its output port section, the coupler turns the multimode light back to a single mode light, and finally couples this light to Si waveguide. The maximum couple efficiency is 86.8% in [Formula: see text] effective coupler length.