Near Infrared LED Guide

What Is a Near-Infrared LED?

A near-infrared (NIR) LED is a light-emitting diode that emits near infrared light, from the deep red edge of the visible spectrum to just beyond it. The CIE defines IR-A as radiation from 780 nm to 1,400 nm[1], and RP Photonics gives the near-infrared region as roughly 750 to 1,400 nm[2]. Tech-LED lists its IR & NIR LEDs from 700 nm to 1,050 nm[3] and its SWIR LEDs from 1,050 nm to 1,900 nm[4], so the NIR LEDs described here cover the lower part of the IR-A band and, from 700 to 780 nm, the deep red just below it, and SWIR LEDs take over above it.

Like any LED, an NIR LED is a semiconductor diode: when it is forward-biased, electrons and holes recombine and release photons. The bandgap of the semiconductor sets the photon energy and therefore the wavelength. For deep red and near-infrared emission, aluminum gallium arsenide (AlGaAs) is a common material[5], and the Tech-LED datasheets for SMT810, SMT850D, SMT880, SMT940 and SMT940D all list an AlGaAs chip[6][7][8][9][10]. The packages range from Φ5 mm through-hole lamps to SMD parts such as the 3.5 x 2.8 mm SMT family, the 3.5 x 3.5 mm EDC family and the 5 x 5 mm SMBB family[11][12].

Human vision does not stop sharply at 700 nm. Eye responsivity falls gradually through the visible red, and RP Photonics notes that light from some laser diodes beyond 750 nm can be seen if it is intense enough[2]; ICNIRP likewise notes visual sensation beyond 780 nm for very bright sources[13]. In practice, an 850nm LED can show a faint glow of visible red light when you look at the source, while a 940nm LED is further from the visible range and much less visible, though a very bright source can still be seen. Silicon sensors detect both. That combination, light that people notice little and electronics respond to, is why NIR LEDs serve as illumination and signaling sources in cameras, sensors and instruments.

Tech-LED datasheets are issued by Marubeni America Corporation[6], and Tech-LED.com is the Marubeni America Corporation, Silicon Valley Branch site for UV, IR, NIR and SWIR LEDs[14]. The product section below lists catalog part numbers and datasheet values.

How NIR LEDs Work

Electrically, a near-infrared LED works like a visible LED, by electroluminescence. Current through the p-n junction pushes electrons and holes together, and when an electron falls into a hole it releases the energy difference as a photon. The photon energy follows E = hc/λ[15], which for a quick estimate becomes λ (in µm) ≈ 1.24 / Eg (in eV). An AlGaAs composition with Eg of about 1.45 eV gives roughly 855 nm. Gallium arsenide, with a bandgap of 1.441 eV, has a bandgap wavelength of 857 nm[16]. The quick formula is only a starting point: the 940 nm parts in the Tech-LED catalog are also listed with AlGaAs chips[7], so the emitted wavelength depends on the device's layer structure and operating temperature, not on the bulk bandgap alone. RP Photonics adds that a temperature increase raises the emission wavelength[5].

The bandgap also sets the operating voltage. RP Photonics notes that the forward voltage of an LED is largely determined by its bandgap energy[5], which is why NIR LEDs run at lower forward voltage than blue or green LEDs. In the Tech-LED datasheets, SMT810 through SMT940D list typical forward voltages of 1.3 to 1.6 V at 50 mA[6][7][8][9][10].

An LED does not emit at one wavelength. RP Photonics describes LED emission bandwidths of about 40 nm and sometimes more than 100 nm, far broader than a laser diode, with much lower coherence[5]. The datasheets quantify it: half width at 50 mA is 32 nm for SMT850D, 40 nm for SMT940D and 50 nm for SMT940[6][7][8]. Treat the nominal wavelength as the center of a band, and look at the peak-wavelength range on the datasheet for the sensor or filter you plan to pair with it.

NIR LED Wavelength Range (700-1050 nm) & Specs

Tech-LED's catalog includes NIR LEDs at 730, 760, 780, 810, 850, 880, 940, 970 and 980 nm, among other wavelengths[12][17][18]. Above that, the SWIR range starts at 1,050 nm[4]. Tech-LED has dedicated guides for 850 nm and 940 nm LEDs, and a separate guide covers 780 nm LED light sources for designs closer to the red end of the band.

Typical Electrical & Optical Specs. Near IR devices share many characteristics with visible LEDs. The table below lists datasheet values for representative Tech-LED parts. All values are typical unless marked as a range, and all are taken at the test current shown (case temperature 25 °C).

Table 1. Datasheet values for representative Tech-LED NIR LEDs

Part	Peak wavelength λp (nm, min to max)	Half width (nm)	Forward voltage VF typ (V)	Total radiated power PO typ (mW)	Test current	Rise / fall time (ns)
SMT810	800 to 820	30	1.6	24	50 mA	20 / 30
SMT850D	840 to 865	32	1.5	26	50 mA	10 / 10
SMT880	875 to 895	37	1.5	25	50 mA	10 / 15
SMT940	930 to 950	50	1.3	15	50 mA	1000 / 1000
SMT940D	930 to 955	40	1.4	30	50 mA	10 / 15
EDC850D-1100	840 to 865	37	1.8	780	1 A	35 / 20
EDC940D-1100	930 to 955	48	1.7	630	1 A	35 / 20
SMBB940DS-3100S-I	930 to 950	47	9.0 (three chips)	3200	1 A	10 / 15

Sources: Tech-LED datasheets[6][7][8][9][10][19][20][21].

Table 2. One example part per common NIR LED peak wavelength

Peak wavelength	Example part	λp (nm, min to max)	Half width (nm)	PO typ	Test current	Notes
730 nm	EDC730D-1100	720 to 740	20	480 mW	600 mA	AlGaInP chip, 3.5 x 3.5 mm
810 nm	SMT810	800 to 820	30	24 mW	50 mA	AlGaAs chip
850 nm	SMT850D	840 to 865	32	26 mW	50 mA	AlGaAs chip
880 nm	SMT880	875 to 895	37	25 mW	50 mA	AlGaAs chip
940 nm	SMT940D	930 to 955	40	30 mW	50 mA	AlGaAs chip
970 nm	SMT970D	960 to 980	55	30 mW	50 mA	AlGaAs chip
980 nm	SMT980D	970 to 990	55	30 mW	50 mA	AlGaAs chip

Sources: Tech-LED datasheets[6][7][9][10][22][23][24].

Four points from the tables deserve attention before you compare parts.

Output depends on the package family, not only the wavelength. Among the SMT parts, the 940 nm SMT940D (30 mW at 50 mA) is rated higher than the 850 nm SMT850D (26 mW at 50 mA), while the 940 nm SMT940 is rated lower (15 mW). Among the EDC parts, the 850 nm EDC850D-1100 (780 mW at 1 A) is rated higher than the 940 nm EDC940D-1100 (630 mW at 1 A), and the DS versions follow the same order, 1400 mW for EDC850DS-1100 and 1300 mW for EDC940DS-1100 at 1 A[6][7][8][19][20][25][26]. A blanket statement that one wavelength is always brighter does not hold across Tech-LED parts. Compare like with like, at the same test current, from the datasheet.

Rise and fall times differ by a factor of 100. SMT850D lists 10 ns each, SMT940 lists 1,000 ns each[6][8]. If you modulate the LED, check tr and tf against your signal rate.

Currents and ratings come with conditions. The SMT850D is tested at 50 mA, and its absolute maximum DC forward current is 100 mA at a case temperature of 25 °C. Its pulse rating is 1,000 mA at 1% duty and 10 µs pulse width[6]. The 100 mA limit is a ceiling, not a recommended operating point, and the precautions page notes that the maximum forward current decreases as temperature rises[27].

Lens options change the beam, not the power. The SMT850D family keeps the same 26 mW total radiated power at 50 mA while a lens narrows the beam and raises the on-axis radiant intensity:

Table 3. SMT850D lens options

Part	Viewing half angle θ1/2	Radiant intensity IE typ at 50 mA
SMT850D	±61°	8.6 mW/sr
SMT850D-23	±18°	50 mW/sr
SMT850D-25	about ±20° (catalog)	not listed in catalog
SMT850D-27	about ±29° (catalog)	not listed in catalog
SMT850D-29	about ±45° (catalog)	not listed in catalog
SMT850D-S1	±8°	140 mW/sr

Values for SMT850D, SMT850D-23 and SMT850D-S1 are from their datasheets[6][28][29]; the other angles are the approximate catalog values[30]. The 940 nm SMT940 family has the same suffix scheme, for example SMT940-25 (15 mW, catalog angle about 20°) and SMT940-27 (15 mW, about 35°)[31].

NIR LED Applications: Industrial, Security, Medical and Consumer

Near-infrared LEDs serve wherever a system needs controlled illumination that the eye notices little but a silicon sensor responds to. Tech-LED's IR & NIR category page lists security cameras and facial-recognition floodlights, pulse oximetry, time-of-flight ranging, and plastic and moisture sorting in industrial automation among the applications[3], and its About page names machine vision, medical devices, security cameras and portable tech gadgets[14]. The bullets below add the engineering reason for each.

• Machine Vision & Industrial Automation: NIR LEDs light parts for cameras on a production line without adding visible glare for operators. Silicon photodiodes have good sensitivity from roughly 400 to 1,000 nm, best around 800 to 900 nm[32], and silicon sensors respond more strongly at 850 nm than at 940 nm[32][34], so 850 nm LED lighting pairs well with them. NIR sensing is an established method in plastics sorting[33]. Optical encoders and similar sensing devices use photodiodes to detect transmitted or reflected light[32]. One limit matters for inspection: silicon has a bandgap wavelength of 1.1 µm[16] and its absorption drops sharply near 1,100 nm[34], so imaging through silicon needs wavelengths beyond that. That is SWIR territory, where Tech-LED's range runs from 1,050 nm to 1,900 nm[4].
• Security & Surveillance: IR illuminators extend what a camera can see at night, and Tech-LED lists security cameras among its applications[3]. For camera illuminators, this guide compares 850 nm and 940 nm. At a given test current, SMT940D (30 mW) and SMT850D (26 mW) are within a few milliwatts of each other, and at 1 A the 850 nm EDC850D-1100 (780 mW) leads the 940 nm EDC940D-1100 (630 mW)[6][7][19][20]. Effective camera range at 940 nm is usually lower, mainly because silicon sensors are less sensitive there[32][34]. For a full OEM walkthrough, see the night vision security camera integration guide and the 850 nm vs 940 nm comparison.
• Medical Devices & Life Sciences: Pulse oximeters measure blood oxygen saturation from red and NIR light absorption, and how deep that light penetrates depends on the wavelength and on the spacing between the LED and the photodetector[35]; see our guide to pulse oximeter LED wavelengths. Vein finders exploit a related contrast: light between 740 nm and 940 nm penetrates about 5 mm into skin tissue and is absorbed by deoxygenated hemoglobin, so veins appear dark[36]. For fNIRS component choices, see our fNIRS wavelength selection guide.
• Consumer Electronics: Infrared remote controls send modulated infrared light that a PIN photodiode receiver detects[32]. IR LED and photodetector pairs are also used for hand gesture sensing based on reflected infrared light[37]; the 940 nm gesture and proximity sensing guide covers the design details. Head-mounted eye trackers use infrared illumination of the eye[38], and iris recognition uses near-infrared at roughly 700 to 900 nm[39]; iris and retina biometrics typically illuminate the eye with infrared LEDs[40].
• Scientific & Specialty: The normalized difference vegetation index (NDVI) compares reflected visible and near-infrared light, because healthy vegetation absorbs most visible light and reflects a large share of near-infrared[41]. A close-range camera system needs its own NIR source to apply the same idea, which is a job for NIR LEDs. LEDs are also used in optical fiber communications[5].

Note on special applications. Tech-LED's precautions page says its standard products are intended for general electronic equipment and asks customers to contact Marubeni America Corporation, Silicon Valley Branch, in advance for special applications such as medical and security equipment, where failure could affect life or health[27]. The datasheets likewise state that the products are not guaranteed for uses where failure may cause injury, including medical devices and safety devices[6].

Across these uses the pattern is the same: a controlled, fast, compact light source in a band that silicon sensors respond to and people notice little.

Eye Safety: IEC 62471 Risk Groups

Near-infrared light is not harmless because it is hard to see. It is transmitted and focused onto the retina just as visible light is, but it does not trigger the protective blink reflex[2]. ICNIRP's exposure guidelines cover 380 nm to 1 mm, evaluate the retinal thermal hazard over 380 to 1,400 nm, and include a separate exposure limit for infrared sources without a strong visual stimulus[13]. Beyond about 1,400 nm, light is absorbed in the front of the eye before it reaches the retina[2].

Which standard applies to LEDs. IEC 62471 covers photobiological safety of lamps and lamp systems, including LEDs but excluding lasers, from 200 nm to 3,000 nm, and provides an exposure-limit and classification scheme[42]. IEC 60825-1 is the standard for laser products[43]. For an NIR LED, the relevant framework is therefore IEC 62471, which classifies sources into risk groups, not laser classes.

What Tech-LED says. Tech-LED's precautions page states that LEDs are within the scope of IEC 62471 and that even its products may fall under Risk Group 2 depending on the customer's conditions of use. It adds that equipment which falls under a risk group should display appropriate warning signs, and that users should apply exposure controls such as protective glasses, gloves and long sleeves[27]. Tech-LED ties the risk group to the conditions of use rather than to a part number, so evaluate your assembled illuminator[27].

Arrays deserve extra attention. Few single LED sources can cause direct eye damage because they emit incoherent light, but researchers have raised concern about LED arrays used in biometric devices[40]. A multi-chip part such as the three-chip SMBB940DS-3100S-I (3200 mW typical at 1 A)[21] or a 16-chip COB (see the product section) is a very different exposure than a single 26 mW emitter.

Practical Eye Safety Tips:

• Never stare into a powered NIR LED at close range, even if it looks dim or appears off. The eye may not warn you.
• Check illumination with an IR viewer card or an IR-sensitive camera rather than the naked eye.
• Enclose or shield powerful LED arrays so end users cannot remove diffusers or covers and look into the source.
• Measure irradiance at the distances where a person can realistically be, and compare against the limits for your product category.
• Add a status indicator that shows when the illuminator is on, since the output itself gives little visible cue.
• For high-power illumination, choose protective eyewear rated for the wavelength in use, and follow the exposure controls Tech-LED lists on its precautions page[27].

Only a measurement of the finished product tells you its risk group. See Tech-LED's handling and use precautions for the full text.

Tech-LED Product Line: 850nm and 940nm NIR LEDs, Arrays + Datasheet Links

Tech-LED lists near-infrared LEDs from single-chip SMT parts to multi-chip arrays. This section highlights catalog parts at 850 nm and 940 nm, with datasheet values and their test conditions.

SMT850D Series (850 nm SMT LEDs)

SMT850D is a 3.5 x 2.8 mm surface-mount LED with a single 350 x 350 µm AlGaAs chip and a peak wavelength of 850 nm typical. At 50 mA it is rated at 26 mW total radiated power, 8.6 mW/sr radiant intensity, 1.5 V typical forward voltage and ±61° viewing half angle. The absolute maximum DC forward current is 100 mA, with a pulse rating of 1,000 mA at 1% duty and 10 µs. The operating range is -40 to +100 °C[6]. Lens variants SMT850D-23, -25, -27 and -29 narrow or widen the beam (see Table 3 above), and SMT850D-S1 has a ±8° half angle and 140 mW/sr[28][29]. The 850 nm LED guide goes deeper on SMT850D and the higher-power 850 nm parts.

SMT940D and SMT940 Series (940 nm SMT LEDs)

At 940 nm the SMT family has two versions. SMT940D is rated 30 mW total radiated power and 10 mW/sr at 50 mA, with 1.4 V typical forward voltage, 40 nm half width and ±61° half angle[7]. SMT940 is rated 15 mW and 5.8 mW/sr at 50 mA, 1.3 V, 50 nm half width, ±64° half angle and an epoxy lens[8]. Both use AlGaAs chips with 100 mA absolute maximum DC current and 1,000 mA pulse rating at 1% duty and 10 µs, and both give 80 K/W as Rthja, which the precautions page says should be read as Rthjs[7][8][27]. SMT940-23, SMT940-25 and SMT940-27 are lensed versions of SMT940 at 15 mW[31]. The 940 nm LED guide covers proximity and gesture design.

High Power LED Options: EDC, SMBB and COB Parts (850nm and 940nm)

For longer range or more output, Tech-LED lists high-power NIR LED products in 3.5 x 3.5 mm EDC and 5 x 5 mm SMBB packages and on COB boards:

• EDC850D-1100 and EDC940D-1100: 780 mW and 630 mW typical total radiated power at 1 A, with 1.8 V and 1.7 V typical forward voltage at 1 A, 10 K/W thermal resistance (datasheet Rthja, read as Rthjs[27]) and 1,000 mA absolute maximum DC current[19][20].
• EDC850DS-1100 and EDC940DS-1100: 1400 mW and 1300 mW typical at 1 A, with forward voltages of 3.2 V and 3.0 V typical at 1 A[25][26].
• SMBB940DS-3100S-I: three AlGaAs chips, 3200 mW typical total radiated power at 1 A and 9.0 V typical forward voltage, 5 K/W thermal resistance (Rthja, read as Rthjs[27])[21]. The catalog lists it under SMBB with secondary optics[11].
• COB850DS-16100S: 16 AlGaAs chips, 850 nm, 51 V typical forward voltage at 1 A (20 ms), 70 W power dissipation rating, -40 to +85 °C operating temperature[44]. The datasheet lists total radiated power of 14 W at 1 A and 20 ms, shown in parentheses[44].

Other NIR Wavelengths, Multi-Wavelength LEDs and Photodiodes

Beyond 850 and 940 nm, the catalog includes SMT810 (810 nm, 24 mW at 50 mA) and SMT880 (880 nm, 25 mW at 50 mA)[9][10], and 970 and 980 nm parts such as SMT970D, SMT980D, EDC970D-1100, EDC980D-1100 and SMBB970D-1100[18]. Multi-wavelength options include the through-hole bi-color lamps L760/850-04A and L760/940-04A and the multi-wavelength SMBB part SMB660D/730/805D/940D-4040, listed at 660, 730, 805 and 940 nm[12].

To pair a detector with the emitter, Tech-LED lists silicon PIN photodiodes such as PD006-SMT, with 0.6 A/W typical responsivity at 900 nm, a 600 µm chip, ±58° half angle of sensitivity and 6 ns rise time[45]. For the SWIR range, Tech-LED lists LEDs from 1,050 nm to 1,900 nm[4].

Part pages link to their datasheets, and the datasheet library is the place to browse the PDFs. The Wavelength Search tool in the site menu lets you filter parts by peak wavelength, for example parts between 840 and 860 nm. The About page also states that multi-wavelength LEDs, custom LEDs, LED die and chip-on-board solutions are available[14]; send requirements through the contact page. If you are still selecting a part, read the guide to choosing the right NIR LEDs for your business.

Design Checklist (Drive Current, Thermal, Optics)

Use this checklist when you design an NIR LED into a product, whether the part is an 850 nm or a 940 nm device.

Drive Current & Pulsing

Decide on drive current and method first. An LED current rises exponentially with voltage, so drive it from a stabilized current source or a series resistor on a fixed supply, not from a constant voltage[5]. Stay inside the absolute maximum ratings, including the spike current that can occur when the power switch turns on and off, which the precautions page warns about[27].

For pulsed operation, use the datasheet's pulse conditions. SMT850D allows 1,000 mA at 1% duty and 10 µs pulse width[6]. At that duty the average current is 10 mA (calculation: 1,000 mA x 0.01), and a 10 µs pulse at 1% duty repeats every 1 ms. Pulsing lets a sensor or illuminator use a high peak output, but the heat is set by the average power and the peak current still has to stay below the pulse rating from the "Forward Current – Pulse Duration" curve[27].

Check rise and fall times against your modulation rate. SMT850D lists 10 ns each at 50 mA, while SMT940 lists 1,000 ns each, so a design that works with one may not work with the other[6][8].

Thermal Management

Part of the input power leaves as light and the rest becomes heat. Input power is Pd = VF x IF[27]. For SMT850D at 50 mA, that is 1.5 V x 50 mA = 75 mW in, with 26 mW typical out as light, so about 49 mW is heat (calculation from typical datasheet values)[6].

Tech-LED's precautions page gives the junction temperature relation Tj = Rthjs x Pd + Ts, where Ts is the solder point temperature, and notes that some datasheets show thermal resistance as Rthja but it should be read as Rthjs, junction to solder point[27]. On that basis, the datasheets list 80 K/W for SMT850D and SMT940D, 10 K/W for EDC850D-1100 and 5 K/W for SMBB940DS-3100S-I[6][7][19][21]. Worked example (calculation): SMT850D at 50 mA gives 80 K/W x 0.075 W = 6 K above the solder point; EDC850D-1100 at 1 A with 1.8 V typical gives 10 K/W x 1.8 W = 18 K above the solder point. 1 A is also the absolute maximum DC forward current for EDC850D-1100 at a case temperature of 25 °C, so a continuous design would normally run lower[19][27]. Absolute maximum ratings are specified at a case temperature of 25 °C; as temperature increases, the maximum forward current and allowable loss decrease[27].

Heat also costs light. RP Photonics notes that a temperature increase decreases the quantum efficiency of an LED and increases the emission wavelength, so effective cooling is essential for high-power LEDs[5]. Use a metal-core board or large copper pads under high-power parts, add airflow or a chassis heat path where needed, and the precautions page recommends checking Tj in the real equipment environment, especially when LEDs are mounted in a row[27].

Optics and Beam Shaping

Decide whether you need a narrow beam to reach a far target or a wide flood. Lens suffixes on Tech-LED parts give a rough guide: on SMT850D, the -23 lens has a ±18° half angle, -25 is about ±20°, -27 about ±29°, -29 about ±45°, and -S1 is ±8° (see Table 3)[28][29][30]. With a bare chip or a flat-window package you will need external optics such as TIR lenses, reflectors or diffusers. A collimating lens gives a tight spot for machine vision, a diffuser spreads light evenly for a camera.

Check every element in the optical path for transmission at your wavelength. Windows, covers and coatings designed for visible light may not pass 850 or 940 nm well, so confirm the transmission curve at your wavelength before choosing a material. When 850 nm and 940 nm LEDs share a system, their half widths and patterns differ (Table 1), so adjust the optics for each.

Power Supply and Switching

Series strings add forward voltage. A string of identical LEDs needs a supply with enough headroom for the sum of the maximum forward voltages. The datasheets show how fast this grows: the three-chip SMBB940DS-3100S-I lists 9.0 V typical at 1 A, and the 16-chip COB850DS-16100S lists 51 V typical at 1 A[21][44]. Size the driver for the maximum VF, not the typical value, and keep it stable with a current-regulated design.

Forward voltage changes with temperature. The SMT850D datasheet includes a forward voltage versus ambient temperature curve[6], and RP Photonics notes that LEDs normally cannot be operated with a constant voltage[5]. This is another reason to use constant-current regulation. When you synchronize LED pulses with a camera exposure, as machine vision strobes do, make sure the timing is controlled and the LED can handle the duty cycle.

Eye Safety & Regulations

As covered in the eye safety section above, plan for IEC 62471 evaluation of the finished product[27][42]. If a product or system falls into a risk group, show the warning signs and instructions that go with it. Add a status indicator, enclose arrays, and keep documentation of the measurements you took. Record the risk group you assign to the finished product, since only measurement can establish it.

Environmental Considerations

The SMT850D, SMT940D, SMT940, SMT810 and SMT880 datasheets all give an operating temperature range of -40 to +100 °C, the EDC parts list the same range, and COB850DS-16100S lists -40 to +85 °C[6][7][8][9][10][19][44]. Lens materials differ by part: SMT940 uses an epoxy resin lens, SMT850D uses silicone or epoxy resin, and COB850DS-16100S uses silicone resin[6][8][44]. Soldering is limited to 5 seconds at 250 °C on the SMT datasheets[6], and the precautions page covers ESD and handling[27]. The datasheets do not state ingress-protection ratings, so sealing against dust and water is a housing and window job. In applications with wide temperature swings, verify solder joints and mounting against the pulse and thermal conditions you actually use.

Matching Detectors

An NIR LED is usually half of a system, paired with a photodiode, phototransistor or camera sensor. Silicon photodiodes have good sensitivity between roughly 400 and 1,000 nm, best around 800 to 900 nm[32]. Tech-LED's PD006-SMT silicon PIN photodiode is rated 0.6 A/W typical at 900 nm[45]. Silicon sensitivity is therefore higher at 850 nm than at 940 nm, which is the main reason system range at 940 nm is usually shorter[32][34]. Beyond 1,000 nm, silicon detectors lose sensitivity and InGaAs photodiodes cover roughly 900 to 1,700 nm[32].

If ambient light is a concern, put an optical band-pass filter in front of the detector that matches the LED's peak wavelength and half width, and make sure the filter passband covers the peak-wavelength range on the LED datasheet, not only the nominal wavelength. Together with drive, thermal, optical and safety checks, this gives you the best chance of first-pass success.

850nm vs 940nm Comparison

"850 nm or 940 nm?" is a key selection question for NIR LEDs. Tech-LED has dedicated pages for each wavelength (850 nm, 940 nm) and a longer 850 nm vs 940 nm comparison. The summary here uses datasheet numbers.

Output and Range

LED output depends on the package family, not only the wavelength. In the SMT family, 940 nm SMT940D is rated 30 mW at 50 mA against 26 mW for 850 nm SMT850D. In the EDC family, 850 nm EDC850D-1100 is rated 780 mW at 1 A against 630 mW for 940 nm EDC940D-1100, and the DS versions are 1400 mW and 1300 mW at 1 A[6][7][19][20][25][26]. So there is no universal "stronger" wavelength; choose a specific part and compare datasheet values at the same current. In the field, effective range at 940 nm is usually lower, mainly because silicon camera sensors are less sensitive there[32][34]. The size of the effect depends on the sensor and optics, so measure with your own sensor and optics rather than rely on a rule of thumb.

Visibility (How Noticeable Is the Glow)

An 850 nm LED can show a faint red glow when viewed directly, especially at high power. A 940 nm LED is further from the visible range and much less visible, but it can still be seen at high drive, because very bright sources beyond 780 nm can produce visual sensation[2][13]. If a design must minimize any visible cue, choose 940 nm and evaluate the actual product at its working drive level in darkness. If a faint glow is acceptable, 850 nm gives a stronger silicon sensor response than 940 nm.

Camera Sensitivity

Silicon photodiodes respond across roughly 400 to 1,000 nm, best around 800 to 900 nm[32]; a camera sensor's quantum-efficiency curve depends on its design, so read it from the sensor datasheet. Their sensitivity is higher at 850 nm than at 940 nm, and silicon absorption falls as the wavelength approaches the 1.1 µm bandgap wavelength[34]. Check the sensor's spectral response curve at both wavelengths and test with the actual camera and lens.

Interference and Ambient Light

Sunlight contains infrared, and the atmosphere absorbs part of the solar spectrum, carving troughs into the spectrum at ground level[46]. The 940nm region sits in one of those troughs. By calculation from the ASTM G173-03 global-tilt reference spectrum as tabulated by PVEducation, the average irradiance over 830 to 870 nm is about 0.97 W/m²/nm and over 920 to 960 nm about 0.42 W/m²/nm, so the 940 nm region carries less than half the solar irradiance per nanometer of the 850 nm region[47]. A 940 nm system therefore faces less solar background, which offsets part of the detector's lower sensitivity. Direct sunlight can still overwhelm either wavelength. The tabulated values jump around from one wavelength to the next because of narrow absorption features, so average over the LED's bandwidth and test outdoors.

Applications & Ecosystem

The surrounding components can matter more than the LED. Both 850nm LEDs and 940nm LEDs work with silicon detectors and cameras, so the question is how your specific sensor, filter and lens behave. Tech-LED lists high-power parts at both wavelengths, for example 850 nm EDC850DS-1100 (1400 mW at 1 A) and 940 nm EDC940DS-1100 (1300 mW) and SMBB940DS-3100S-I (3200 mW)[21][25][26]. For iris recognition, the relevant band is roughly 700 to 900 nm, not 940 nm[39]. For gesture and proximity work, see the 940 nm guide.

In summary, choose 850 nm when a silicon sensor needs the most signal and a faint red glow is acceptable. Choose 940 nm when you want less visible illumination or when sunlight is the main noise source, and accept that the sensor will respond less. In either case, Tech-LED lists parts at both wavelengths and in between (810, 880 and 970 to 980 nm), so you can compare datasheet values. If you need more guidance, see our guide to choosing the right NIR LEDs for your business.

Frequently Asked Questions

What wavelength range is near-infrared?

The CIE defines IR-A as 780 nm to 1,400 nm[1], and RP Photonics gives roughly 750 to 1,400 nm[2]. Tech-LED's IR & NIR LED category covers 700 nm to 1,050 nm[3], and its SWIR LEDs run from 1,050 nm to 1,900 nm[4]. The band edges are conventions that vary by field, so state the actual peak wavelength and half width when you specify a part.

What is an NIR light source, and where do LEDs fit?

Near-infrared light sources are anything that emits at near infrared wavelengths: thermal emitters such as incandescent lamps, lasers, and LEDs[2]. LEDs typically emit in a quite limited wavelength range, though substantially wider than a laser, with far lower spatial coherence[2]. That broader, low-coherence near-infrared LED light suits area illumination for cameras, while lasers suit narrow-beam or narrow-line uses. LEDs also offer fast modulation[5], which suits camera and sensor illuminators; check the rise and fall times on the datasheet (10 ns for SMT850D, 1,000 ns for SMT940)[6][8].

What is an NIR LED array?

An NIR LED array puts several LED chips in one package or on one board to raise output. Tech-LED examples are the three-chip SMBB940DS-3100S-I (3200 mW typical total radiated power at 1 A, 9.0 V typical)[21] and the 16-chip COB850DS-16100S at 850 nm (51 V typical forward voltage at 1 A, 20 ms)[44]. Chips in series add forward voltage, so use a current-regulated driver sized for the maximum voltage. Arrays also raise eye-safety and thermal requirements[27][40], so evaluate the finished product under IEC 62471.

Do LEDs emit near-infrared?

A standard visible LED is built to emit in the visible band, with its color set by the semiconductor material, and white LEDs generally combine a blue LED with phosphors[5]. Their output is concentrated in the visible range by design, whereas incandescent lamps are thermal emitters that radiate across the infrared[2]. To get significant near-infrared output you use a purpose-built NIR LED, for example one of the AlGaAs parts above. If your application depends on a particular spectrum, check the relative spectral emission curve on the datasheet instead of assuming.

What is the difference between a normal LED and an infrared LED?

The main difference is the wavelength band. A visible LED's light color is set by a semiconductor with a bandgap that matches visible photon energies; an infrared LED uses a lower-bandgap material such as AlGaAs, whose emission falls in the red-to-near-infrared range[5]. The lower bandgap shows up in the forward voltage: the NIR datasheets above list 1.3 to 1.6 V typical at 50 mA[6][8][9], while RP Photonics notes red LEDs can operate with less than 2 V and blue LEDs need on the order of 4 V[5]. Packages look similar, but you cannot judge by eye whether an IR LED is on: an 850 nm LED may show a faint red glow, a 940 nm LED shows much less, and a camera or IR viewer card confirms the output. An IR LED is typically used for sensing and communication with devices, and for illumination that cameras and sensors respond to.

How efficient is a near-infrared LED?

Wall-plug efficiency, optical power out divided by electrical power in, is the usual measure. From Tech-LED datasheet typical values, the calculated figures run from about 23% to about 43%:

Part	Light out (PO typ)	Electrical in (VF typ x IF)	Calculated efficiency
SMT940	15 mW	1.3 V x 50 mA = 65 mW	23%
SMT850D	26 mW	1.5 V x 50 mA = 75 mW	35%
SMT940D	30 mW	1.4 V x 50 mA = 70 mW	43%
EDC850D-1100	780 mW	1.8 V x 1 A = 1,800 mW	43%

These are calculations from typical values at the test currents shown, not guaranteed ratings[6][7][8][19]. Efficiency varies with the specific part, drive current and temperature: RP Photonics notes that rising temperature reduces LED quantum efficiency[5]. The remainder becomes heat, which is why thermal design matters (see the design checklist). For a broader treatment, read our near-infrared LED efficiency article.

What are infrared LEDs used for?

Infrared LEDs are used wherever a system needs light that a machine detects and a person notices little. Common uses include:

• Remote Controls and IR Communication: the receiver in a TV or appliance uses a PIN photodiode to detect modulated infrared light from the remote[32]. LEDs are also used in optical fiber communications[5].
• Security Camera Illumination: IR illuminators extend what a camera sees at night; Tech-LED lists security cameras and facial-recognition floodlights among its applications[3].
• Gesture and Position Sensing: An IR LED and a photodetector can sense reflected infrared light for gesture detection[37]; optical encoders use photodiodes to detect transmitted or reflected light[32].
• Industrial and Machine Vision: NIR illumination for cameras and sorting, for example plastics sorting[3][33].
• Medical and Biomedical: pulse oximeters use red and infrared light absorption[35], and vein finders use light between 740 and 940 nm[36]. See our medical devices article for component-level detail.
• Consumer Electronics & Biometrics: eye-tracking systems use infrared illumination[38], and iris recognition uses near-infrared at roughly 700 to 900 nm[39].

Each use pairs the emitter with a detector, so see the design checklist above for matching.

How does an infrared LED work?

Infrared light emitting diodes (IR LEDs) work like any LED, by electroluminescence at a semiconductor junction[5]:

• When forward-biased, electrons from the n-type side cross the junction and recombine with holes on the p-side. Each recombination releases the bandgap energy as a photon.
• The bandgap sets the wavelength, λ ≈ 1.24 / Eg (µm, eV). GaAs, with a bandgap of 1.441 eV, corresponds to 857 nm[16]. Mixing in aluminum to form AlGaAs lets the manufacturer tune the emission across the red-to-NIR range[5].
• The chip sits in a package, often with a lens, that shapes the beam. SMT850D and SMT940D, for example, list ±61° viewing half angles[6][7].
• You apply a forward voltage, about 1.3 to 1.6 V typical at 50 mA for the SMT parts in Table 1, but you set the current with a regulator, not the voltage[5]. An 850 nm LED may show a faint red glow, and a camera or IR viewer card shows the rest.
• Switching speed depends on the part: from 10 ns rise and fall for SMT850D to 1,000 ns for SMT940[6][8].

The physics is the same as for a visible LED; only the material differs, so the photons are in the infrared.

Where can I find a detailed cost comparison of near-infrared LEDs vs traditional IR solutions?

See our Cost Analysis: Investing in Near Infrared LEDs vs. Traditional Solutions.

Does the Tech-LED.com catalog list IR LED strips?

Tech-LED's catalog lists component LEDs in through-hole, SMT, EDC, SMBB and COB packages and does not list finished IR LED strips[3][14]. A strip builder would use components such as the SMT850D or SMT940D, and the drive and thermal rules in the design checklist apply to the string.

Sources

1. CIE, International Lighting Vocabulary (ILV), "IR-A" (infrared radiation from 780 nm to 1,400 nm). cie.co.at/eilvterm/17-21-005
2. R. Paschotta, "Infrared Light," RP Photonics Encyclopedia (near-infrared region, also called IR-A, about 750 to 1,400 nm; focused onto the retina without triggering the blink reflex; eye responsivity falls gradually beyond the red). rp-photonics.com/infrared_light.html
3. Tech-LED, "IR & NIR LEDs" product category (700 nm to 1,050 nm; applications). https://tech-led.com/product/ir-nir-leds/
4. Tech-LED, "SWIR LEDs," 1,050 to 1,900 nm. https://tech-led.com/product/swir-led/
5. R. Paschotta, "Light-Emitting Diodes," RP Photonics Encyclopedia (AlGaAs and near-infrared LEDs; emission bandwidth; forward voltage set by bandgap; constant-current operation; temperature effects). rp-photonics.com/light_emitting_diodes.html
6. Marubeni America, SMT850D data sheet. https://tech-led.com/wp-content/uploads/2024/04/SMT850D.pdf
7. Marubeni America, SMT940D data sheet. https://tech-led.com/wp-content/uploads/2024/04/SMT940D.pdf
8. Marubeni America, SMT940 data sheet. https://tech-led.com/wp-content/uploads/2024/04/SMT940.pdf
9. Marubeni America, SMT810 data sheet. https://tech-led.com/wp-content/uploads/2016/08/SMT810.pdf
10. Marubeni America, SMT880 data sheet. https://tech-led.com/wp-content/uploads/2024/04/SMT880.pdf
11. Tech-LED product catalog pages for package sizes: SMT850D, EDC850D-1100 and SMBB940DS-3100S-I (SMBB with secondary optics). https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt850d/, https://tech-led.com/p/surface-mount/edc/edc850d-1100/, https://tech-led.com/p/high-power-led/smbb-high-power/smbb-secondary-optics/smbb940ds-3100s-i-2/
12. Tech-LED product catalog pages: L760/850-04A, L760/940-04A and SMB660D/730/805D/940D-4040. https://tech-led.com/p/through-hole/l760850-04a/, https://tech-led.com/p/through-hole/l760940-04a/, https://tech-led.com/p/surface-mount/smbd-and-smbb/smb660d730805d940d-4040/
13. ICNIRP, "Guidelines on Limits of Exposure to Incoherent Visible and Infrared Radiation," Health Physics 105(1):74-96, 2013 (IR-A 780 to 1,400 nm; retinal thermal hazard 380 to 1,400 nm; visual sensation beyond 780 nm for very bright sources). icnirp.org/cms/upload/publications/ICNIRPVisible_Infrared2013.pdf
14. Tech-LED, "About Us." https://tech-led.com/about-us/
15. R. Paschotta, "Photons," RP Photonics Encyclopedia (photon energy E = hc/λ). rp-photonics.com/photons.html
16. R. Paschotta, "Band Gap," RP Photonics Encyclopedia (table: GaAs 1.441 eV, 857 nm; silicon 1.12 eV, 1.1 µm). rp-photonics.com/band_gap.html
17. Tech-LED product catalog pages: SMT810, SMT880, EDC730D-1100 and L780-02AU. https://tech-led.com/p/ir-nir-leds/through-hole-ir-nir-led/l780-02au/, https://tech-led.com/p/surface-mount/smt/smt810/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt880/, https://tech-led.com/p/surface-mount/edc/edc730d-1100/
18. Tech-LED product catalog pages: SMT970D, SMT980D, EDC970D-1100, EDC980D-1100 and SMBB970D-1100. https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt970d/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt980d/, https://tech-led.com/p/surface-mount/edc/edc970d-1100/, https://tech-led.com/p/surface-mount/edc/edc980d-1100/, https://tech-led.com/p/ir-nir-leds/smbb-ir-nir-led/smbb970d-1100/
19. Marubeni America, EDC850D-1100 data sheet. https://tech-led.com/wp-content/uploads/2023/11/EDC850D-1100.pdf
20. Marubeni America, EDC940D-1100 data sheet. https://tech-led.com/wp-content/uploads/2023/11/EDC940D-1100.pdf
21. Marubeni America, SMBB940DS-3100S-I data sheet. https://tech-led.com/wp-content/uploads/2024/03/SMBB940DS-3100S-I.pdf
22. Marubeni America, EDC730D-1100 data sheet. https://tech-led.com/wp-content/uploads/2023/11/EDC730D-1100.pdf
23. Marubeni America, SMT970D data sheet. https://tech-led.com/wp-content/uploads/2016/08/SMT970D.pdf
24. Marubeni America, SMT980D data sheet. https://tech-led.com/wp-content/uploads/2023/12/SMT980D.pdf
25. Marubeni America, EDC850DS-1100 data sheet. https://tech-led.com/wp-content/uploads/2016/08/EDC850DS-1100.pdf
26. Marubeni America, EDC940DS-1100 data sheet. https://tech-led.com/wp-content/uploads/2023/11/EDC940DS-1100.pdf
27. Tech-LED, "Epitex series handling and use precautions" (IEC 62471 scope and Risk Group 2 statement; Tj = Rthjs x Pd + Ts; Rthja to be read as Rthjs; absolute maximum ratings). https://tech-led.com/epitex-series-handling-and-use-precautions/
28. Marubeni America, SMT850D-23 data sheet. https://tech-led.com/wp-content/uploads/2016/08/SMT850D-23.pdf
29. Marubeni America, SMT850D-S1 data sheet. https://tech-led.com/wp-content/uploads/2024/04/SMT850D-S1.pdf
30. Tech-LED product catalog pages: SMT850D-25, SMT850D-27 and SMT850D-29 (approximate viewing angles). https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt850d-25/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt850d-27/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt850d-29/
31. Tech-LED product catalog pages: SMT940-23, SMT940-25 and SMT940-27. https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt940-23/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt940-25/, https://tech-led.com/p/ir-nir-leds/smt-ir-nir-led/smt940-27/
32. R. Paschotta, "Photodiodes," RP Photonics Encyclopedia (silicon good between roughly 400 and 1,000 nm, best around 800 to 900 nm; InGaAs roughly 900 to 1,700 nm; remote-control receivers; optical encoders). rp-photonics.com/photodiodes.html
33. "Influences of bioplastic polylactic acid on near-infrared-based sorting of conventional plastic," Waste Management & Research 39, 2021, doi:10.1177/0734242×211003969. pmc.ncbi.nlm.nih.gov/articles/PMC8488636
34. C. Honsberg and S. Bowden, "Optical Properties of Silicon," PVEducation (absorption drops sharply at the band gap, around 1,100 nm). pveducation.org/pvcdrom/materials/optical-properties-of-silicon
35. Skin pigmentation influence on pulse oximetry accuracy: a systematic review and bibliometric analysis, Sensors 22(9):3402, 2022, doi:10.3390/s22093402 (pulse oximeters estimate oxygen saturation from red and infrared light absorption). pmc.ncbi.nlm.nih.gov/articles/PMC9102088
36. "Vein Pattern Locating Technology for Cannulation: A Review of the Low-Cost Vein Finder Prototypes Utilizing Near Infrared (NIR) Light," Sensors 19(16):3573, 2019, doi:10.3390/s19163573 (740 to 940 nm light penetrates about 5 mm of skin tissue and is absorbed by deoxygenated hemoglobin). pmc.ncbi.nlm.nih.gov/articles/PMC6719195
37. M. Z. Islam et al., "Hand Gesture Recognition through Reflected Infrared Light Wave Signals," arXiv:2301.05955 (ICEEE 2023). arxiv.org/abs/2301.05955
38. "A Comprehensive Eye-Tracking System Toward Large FOV HMD," Sensors 26(5):1402, 2026, doi:10.3390/s26051402 (head-mounted eye tracking with ring-shaped infrared illumination). pmc.ncbi.nlm.nih.gov/articles/PMC12986753
39. NIST, IR 8252, iris recognition (near-infrared, approximately 700 to 900 nm). nvlpubs.nist.gov/nistpubs/ir/2019/NIST.IR.8252.pdf
40. "Eye safety related to near infrared radiation exposure to biometric devices," The Scientific World Journal 2011, doi:10.1100/tsw.2011.52 (iris and retina biometrics illuminate the eye with infrared LEDs; concern about LED arrays). pmc.ncbi.nlm.nih.gov/articles/PMC5720004
41. NASA Earth Observatory, "Measuring Vegetation (NDVI & EVI)" (healthy vegetation absorbs most visible light and reflects a large portion of near-infrared light). science.nasa.gov/earth/earth-observatory/measuring-vegetation-ndvi-evi
42. IEC 62471:2006, "Photobiological safety of lamps and lamp systems," IEC Webstore (covers LEDs, excludes lasers, 200 to 3,000 nm; exposure limits and classification scheme). webstore.iec.ch/en/publication/7076
43. IEC 60825-1:2014, "Safety of laser products, Part 1: Equipment classification and requirements," IEC Webstore (laser products, 180 nm to 1 mm). webstore.iec.ch/en/publication/3587
44. Marubeni America, COB850DS-16100S data sheet. https://tech-led.com/wp-content/uploads/2025/11/COB850DS-16100S.pdf
45. Marubeni America, PD006-SMT Si PIN photodiode data sheet. https://tech-led.com/wp-content/uploads/2021/07/PD006-SMT.pdf
46. C. Honsberg and S. Bowden, "Atmospheric Effects," PVEducation (atmospheric absorption carves troughs into the solar spectrum). pveducation.org/pvcdrom/properties-of-sunlight/atmospheric-effects
47. ASTM G173-03(2020), "Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37° Tilted Surface," ASTM International, store.astm.org/g0173-03r20.html. Values used here (AM1.5 global tilt) are as tabulated by C. Honsberg and S. Bowden, PVEducation, "Standard Solar Spectra." pveducation.org/pvcdrom/appendices/standard-solar-spectra