What Is an Infrared (IR) LED?
An infrared LED (IR LED) is an LED that emits invisible infrared light. It works like a visible LED but its wavelength is in the region the human eye can't perceive.
How Does It Work?
Structurally it's the same as a normal LED; only the semiconductor material is chosen to produce infrared light around 850-940 nm. This light is detected by an IR photodiode or receiver module.
Transmitter-Receiver Pair
An IR LED is rarely used alone; it's usually paired with a receiver (photodiode/phototransistor/IR module). The transmitter sends the light, the receiver converts it into an electrical signal.
| Wavelength | Typical use |
|---|---|
| 850 nm | Camera, distance sensing |
| 940 nm | Remote control |
Why Is Modulation Important?
In remote controls the IR light is usually modulated with a carrier such as 38 kHz. So the receiver can distinguish the real signal from sunlight and ambient IR noise.
Where Is It Used?
TV/AC remote controls, proximity and distance sensors, optical encoders, night-vision cameras and IR communication.
Common Mistakes
- Wrong wavelength: the transmitter and receiver wavelengths must match.
- Use without modulation: ambient IR can suppress the signal.
- Current limit: like a normal LED, the current must be limited with a series resistor.
Frequently Asked Questions
How can I see IR light?+
Is an IR LED harmful?+
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