45-Degree Silver Mirror for Broadband Optical Coupling to Ion Traps

Conventional ion traps rely on bulky free-space optics or integration of grating couplers under the electrodes. The grating couplers are narrow-band components, necessitating four different couplers, each individually aligned, focused, and routed. This work presents a single waveguide with a broadband 45° angled mirror acting as an antenna. This structure demonstrated optical coupling from 422 nm to 1092 nm, suitable for Sr+ ion trap systems, with a gain of up to 15.51 to 16.59 dB. The broadband response demonstrated here helps to replace the commonly used four grating couplers and feed waveguides with a single set.