IRLEDs

Infrared Light-Emitting Diodes (IRLEDs) are semiconductor devices that emit infrared radiation when electrically biased. They operate on the same basic principle as visible LEDs—recombination of electrons and holes in a p-n junction produces photons—but the energy gap is smaller, so the emitted photons lie in the infrared portion of the spectrum. IRLEDs are produced in a range of wavelengths, commonly from about 780 nm to 940 nm for short-range, light-insensitive applications, with longer-wavelength devices (1.3–1.6 μm) based on materials such as InGaAs.

Common uses include remote controls, where a 850–940 nm emitter transmits signals to a receiver; security and night-vision cameras use IR illumination; proximity sensors and contactless switches; fiber-optic and free-space optical links; and barcode scanners and industrial sensing. The devices are valued for compact size, low cost, and robustness.

Electrical and optical characteristics vary by design. Typical forward voltages are around 1.2–1.6 V, with drive currents ranging from tens of milliamperes for indicator devices to hundreds of milliamperes for high-power emitters. Emission is broad and non-coherent, and radiant efficiency depends on wavelength and device structure, often lower at longer wavelengths. IRLEDs are available in packages with epoxy or silicone lenses to shape the beam, and arrays or optics can increase output intensity.

Historically, IRLEDs were developed alongside visible LEDs and became widely deployed in the 1990s. Because infrared is not visible to the eye, IRLED radiation is typically detected by sensors, cameras, or photodiodes; high-intensity sources should be handled with appropriate eye safety considerations.