Which detector type converts light directly into an electrical signal without an amplification stage?

Which detector type converts light directly into an electrical signal without an amplification stage?

• A. Photomultiplier tube
• B. Monochromator
• C. Photovoltaic cell
• D. Detector

Answer: (C)

Direct conversion of light into an electrical signal happens through the photovoltaic effect in a photovoltaic cell. When photons are absorbed by the semiconductor, they create electron–hole pairs, and the built‑in electric field of the PN junction separates these carriers to generate a current (or a voltage) without needing any internal amplification. This is different from detectors that rely on gain, such as photomultiplier tubes that amplify electrons through a cascade, or from devices like a monochromator that merely disperses light and isn’t a detector itself. A photovoltaic cell thus provides the electrical signal directly from the light input, making it the correct choice.

Direct conversion of light into an electrical signal happens through the photovoltaic effect in a photovoltaic cell. When photons are absorbed by the semiconductor, they create electron–hole pairs, and the built‑in electric field of the PN junction separates these carriers to generate a current (or a voltage) without needing any internal amplification. This is different from detectors that rely on gain, such as photomultiplier tubes that amplify electrons through a cascade, or from devices like a monochromator that merely disperses light and isn’t a detector itself. A photovoltaic cell thus provides the electrical signal directly from the light input, making it the correct choice.