Laser Light Versus LED Light Power Sources

ICC White Papers

The optical light source is a fundamental part of fiber optic systems. A fiber optic system includes an optical fiber connected to a transmitter and a receiver. The fiber optic light source is produced by the transmitter’s drive circuit synchronizing with the signals that are transmitted. The light source also allows the fiber optic network to be tested. Loss in performance can be calculated in the cable plant – the fiber, splices, or connectors. LED, halogen, and laser are a few of the many types of existing light power sources. LED and laser are semiconductor light sources. The article explains the differences between them.

LED and laser light sources can cast microscopic light beams into an optical fiber while powering up and down billions of times every second. Both light sources are required to be turned on and off quickly for the optical signals to transfer and correspond accurately and completely.

Light Emitting Diode (LED) A. FFDI Overfilled-Launch, Spot Size 100μm, Core 62.5μm

Vertical Cavity Surface Emitting Laser (VCSEL) B. Gigabit Ethernet Short Wavelength, Spot Size 35μm, Core 62.5μm

Single-mode Laser C. Gigabit Ethernet Long Wavelength, Spot Size 10μm, Core 62.5μm


Materials within the LED fiber optic light source affect the wavelengths of light that are emitted. A basic LED light source is a semiconductor diode with a “P” region and an “N” region. Current flows through the LED when the LED is forward biased. The area where the “P” and “N” regions meet emits photons as the current flows through the LED. LEDs are usually made up of a material called gallium aluminum arsenide (GaAIAs) when emitting in the window of 820 to 870 nm.

Similar to LED, laser is also a semiconductor diode with a “P” and an “N” region. However, it provides a stimulated emission rather than the simplex spontaneous emission of LEDs. Laser has an optical cavity designed for long-term stability which is much different than LED. By slicing the opposite end of the chip, the cavity is formed producing a highly parallel, reflective, and mirror-like finish.


A common source for high speed networking is a vertical-cavity surface-emitting laser, otherwise known as VSECL. It consists of two oppositely-doped Distributed Bragg Reflectors with a cavity layer. It’s a perfect choice for the gigabit networking options because it combines high bandwidth with low cost. Between 1975 and 1977, vertical light emitting laser was introduced to resolve the planarization constraints of the integrated photonics as microelectronic technology was only available at the time.

Today, lasers are widely being used for other applications, including laser printers, a computer mouse, chip scale atomic clocks, and analog broadband signal transmission, just to name a few.

Speed, Distance, Cost

When comparing an LED to a laser, the LED is a standard light source and falls short for light-emitting diodes. A laser does provide more power and function at higher speed levels than an LED. A laser also has better accuracy while channeling light over a wider distance. Nevertheless, a laser is not as commonly used compared to an LED and carries a higher price tag.

ICC has a full line of singlemode and multimode connectivity products to support your fiber optic installations. Learn more about ICC’s fiber optic system at