Certified Fiber Optics Practice Exam

Single mode fiber optic systems operate typically at which wavelengths?

1. 850-1310 nm

2. 1300-1550 nm

3. Both 850-1310 nm and 1300-1550 nm

4. 400-800 nm

The correct answer is: Both 850-1310 nm and 1300-1550 nm

Single mode fiber optic systems are designed to carry light directly down the fiber without much reflection, allowing them to transmit data over long distances with minimal signal loss. The common operating wavelengths for single mode fibers typically fall within the infrared wavelength spectrum, specifically around 1300 nm and 1550 nm. The 1300 nm wavelength is significant because it provides a balance between low attenuation and minimal dispersion, which is crucial for maintaining signal quality over longer distances. The higher wavelength of 1550 nm is particularly favored in telecommunications because it has even lower attenuation, enabling higher capacity and longer transmission distances without repeaters. While 850 nm is commonly associated with multimode fiber optics, it's not generally used in single mode applications. Therefore, the correct information regarding the wavelengths that single mode fibers operate at spans from 1300 nm to 1550 nm. This makes the option that includes both 1300 nm and 1550 nm the most accurate choice.