Which of the following options correctly lists a commonly used multimode wavelength pair?

Which of the following options correctly lists a commonly used multimode wavelength pair?

• A. 850 and 1300
• B. 1310 and 1550
• C. 780 and 1064
• D. 850 and 1625

Answer: (A)

For multimode fiber, the wavelengths used in typical demonstrations and testing come from the visible to near-infrared range where inexpensive LED/VCSEL sources and standard detectors are readily available. The pair of 850 nm and 1300 nm is chosen because 850 nm aligns well with the large-core multimode fiber and common LED/VCSEL sources, making coupling straightforward and efficient. At the same time, 1300 nm falls in a low-loss window of silica, where components and detectors exist from telecom-era equipment, enabling practical testing and demonstration of multimode behavior without excessive loss. Other wavelength pairs align more with single-mode telecom systems or specialized lasers. Wavelengths around 1310 nm and 1550 nm are the standard telecom windows for single-mode fiber and long-haul links, not the typical multimode setup. Wavelengths like 780 nm and 1064 nm come from solid-state laser sources rather than the common multimode-fiber LED/VCSEL ecosystem. A pairing of 850 nm with 1625 nm is less standard due to availability and compatibility of components for multimode systems. So the 850 nm and 1300 nm pairing best represents the commonly used multimode wavelength pair.

For multimode fiber, the wavelengths used in typical demonstrations and testing come from the visible to near-infrared range where inexpensive LED/VCSEL sources and standard detectors are readily available. The pair of 850 nm and 1300 nm is chosen because 850 nm aligns well with the large-core multimode fiber and common LED/VCSEL sources, making coupling straightforward and efficient. At the same time, 1300 nm falls in a low-loss window of silica, where components and detectors exist from telecom-era equipment, enabling practical testing and demonstration of multimode behavior without excessive loss.

Other wavelength pairs align more with single-mode telecom systems or specialized lasers. Wavelengths around 1310 nm and 1550 nm are the standard telecom windows for single-mode fiber and long-haul links, not the typical multimode setup. Wavelengths like 780 nm and 1064 nm come from solid-state laser sources rather than the common multimode-fiber LED/VCSEL ecosystem. A pairing of 850 nm with 1625 nm is less standard due to availability and compatibility of components for multimode systems.

So the 850 nm and 1300 nm pairing best represents the commonly used multimode wavelength pair.