What Are the Different Types of IR Diodes?

Jo Dunaway

IR diodes, short for infrared diodes, are semiconductor components that emit light at a wavelength longer than the human eye can visibly detect in most cases. This type of diode is used in a variety of consumer electronics, from television remote controls to the tiny infrared diodes that emit signals from a computer mouse. The diodes in the infrared color spectrum are made of semiconducting materials such as gallium arsenide, which is a mineral crystal, germanium, or aluminum gallium arsenide.

Television remote controls have an IR diode.
Television remote controls have an IR diode.

The way IR diodes work is by converting electrical signals into infrared light that can be beamed to special detectors. These receivers perform the opposite conversion, turning the infrared light into electrical signals once again. The diodes themselves have electrical characteristics that can be modified for different functions by allowing emissions at differing levels of the infrared spectrum. In this manner, some infrared diodes can be used to tune radio and television receivers electronically.

IR diodes include sensitive photodiodes, which perform by sensing light in solar cells and optical equipment.
IR diodes include sensitive photodiodes, which perform by sensing light in solar cells and optical equipment.

There are a wide variety of uses for IR diodes. They are used to trigger security system cameras when infrared proximity sensors detect someone within a focused area. Military uses of infrared include night vision instruments that convert nearby light photons into amplified visible electrons and bring details out of darkness. They are also used in ship bridges, aircraft, and submarine control panels as indicator display lights in low-light conditions.

The infrared signals that operate cellphones and remote controls are operated by a beamed electric signal from diodes at specific frequencies to perform specific tasks, even when signals are faint. Some consumer gaming devices attached to a television use infrared diodes to communicate with interactive games displayed on the screen. In medical equipment, infrared diodes are attached to opto-isolators, which are electrical circuit protection devices. Opto-isolators protect the medical equipment while tests are being run on a patient, so that any electronic interference or noise from nearby medical equipment can be blocked.

One type of IR diode is called a tunnel diode, which works extremely quickly to amplify signals using quantum tunneling in high-radiation environments, such as in a spacecraft. Another type is a light-emitting diode (LED); this type found in approximately 80% of infrared diodes. High-powered infrared LEDs often compete with another type of infrared diode, called laser diodes, in performing similar tasks in optical communication systems. Other IR diodes include the sensitive photodiodes, which perform by sensing light in solar cells and optical equipment. Arrays of LEDs can mimic photodiodes when used in touch-sensing computer screens, sensing light reflections from a stylus or human finger.

Ongoing research is looking into using IR diodes to replace lasers for minor surgeries in dermatology offices as they may be more cost effective. Additionally, research is being done with new nanocrystal infrared diodes. These are called quantum dot LEDs and are being researched to determine if they will be stable enough under prolonged radiation at Vanderbilt University.

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