Which type of devices either produce light or use light in their operation?

Optoelectric devices are specifically designed to either generate light or utilize light as part of their operation. Examples of such devices include light-emitting diodes (LEDs), laser diodes, photodiodes, and optical sensors. These components are crucial in various applications, including communications, displays, and sensors, as they rely on the interaction between electrical energy and light energy.

Digital circuits, while fundamental to electronics, primarily manipulate binary data using voltage levels but do not typically produce light or utilize it actively in their basic operations. Magnetic devices focus on magnetic fields and their interactions rather than light. Finite state machines are a conceptual model used to design algorithms and systems that operate based on defined states and transitions but similarly do not directly engage with light in their functional architecture.

Thus, optoelectric devices are the category that directly involves the production or use of light in their operational principles, making it the correct answer.