Certified Fiber Optics Practice Exam

What is the spectral width of an LED compared to a laser?

1. Narrower

2. Wider

3. Similar

4. Unmeasured

The correct answer is: Wider

The spectral width of an LED is wider compared to that of a laser. This characteristic arises from the different mechanisms of light generation in LEDs and lasers. LEDs emit light through spontaneous emission, resulting in a broader range of wavelengths. This broad spectral output contributes to a wider spectral width, typically in the range of tens to hundreds of nanometers. In contrast, lasers operate on the principle of stimulated emission, producing coherent light with a narrow spectral width, often in the range of just a few nanometers. This coherence and narrow-bandwidth nature of laser light makes it ideal for applications that require precise wavelength control and higher transmission rates. Understanding the spectral width of these light sources is crucial for various optical applications, including fiber optics, where bandwidth and data transmission capabilities can be influenced by the light source's characteristics. The wider spectral width of LEDs means they can cover a larger range of wavelengths, which is suitable for certain types of multiplexing and broader bandwidth communications but may not achieve the same distance and speed as laser-based systems.