There is disclosed in one example a computing apparatus, including: a fiber-optic transmitter including a laser source; an input waveguide to receive a modulated laser pulse from the laser source; an output waveguide to direct the modulated laser pulse to an external communication element; and an isolator bridge optically coupled to the input waveguide and output waveguide, the isolator bridge including an input lens, an input-side folding prism, an isolator element, an output-side folding prism, and an output lens, wherein an input light pulse through the input lens is to be redirected by the input-side folding prism through the isolator element to the output-side folding prism, and redirected by the output-side folding prism through the output lens.