Image sensors and optical devices

Which semiconductor laser has a built-in diffraction grating so that it oscillates stably at a single wavelength for optical communication?

  1. ALED
  2. BDFB laser (distributed feedback laser)
  3. COrganic EL
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Answer: B. DFB laser (distributed feedback laser)

A DFB laser has a periodic structure (diffraction grating) built in near the active layer that strongly feeds back only light of a particular wavelength, making it oscillate at a single wavelength. With its stable wavelength and narrow spectrum, it is used as the light source for long-distance optical fiber communication.

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