Photobiomodulation Explained: How 650, 810 and 980 nm Work
Photobiomodulation (PBM) is the use of red and near-infrared light to influence biological processes in tissue. It is the current scientific term for what used to be called low-level laser therapy, and it now covers a wide range of devices, including Class 4 laser systems used in physiotherapy and rehabilitation.
This article explains the basic idea behind photobiomodulation and why different wavelengths are used, so you can talk about it confidently with colleagues and patients.
What happens when light meets tissue
When light enters the skin, it is absorbed, scattered or transmitted. How deep it travels depends mainly on its wavelength and on the molecules it meets along the way, known as chromophores. The main chromophores in soft tissue are melanin, haemoglobin and water.
Photobiomodulation works within a range often called the optical window, roughly 600 to 1,100 nm. In this range, light is absorbed less by melanin and haemoglobin than shorter visible wavelengths, so it can reach deeper structures.
The proposed mechanism
The most widely discussed mechanism involves cytochrome c oxidase, an enzyme in the mitochondria. Research suggests that absorption of red and near-infrared light by this enzyme may influence mitochondrial activity and cellular signalling. The 800 to 810 nm band is among the most studied wavelengths in photobiomodulation research.
Research in this field is active and evolving. Mechanisms and clinical responses are still being studied, and results depend heavily on wavelength, dose and technique. For a summary of the literature, see our evidence page.
Three wavelengths, three tissue depths
Wavelength | Type of light | Where it is mainly used |
650 nm | Visible red | Superficial tissue, absorbed close to the surface |
810 nm | Near-infrared | Deeper tissue; the most studied band in photobiomodulation research |
980 nm | Near-infrared | Absorbed by water and haemoglobin; used in advanced deep-tissue protocols to support microcirculation and oxygen delivery |
650 nm: superficial tissue
Red light at 650 nm is absorbed relatively close to the skin surface. It is typically chosen when the target tissue is superficial, for example in protocols involving the skin and the tissues just beneath it.
810 nm: deeper reach
Near-infrared light at 810 nm is absorbed less by melanin and haemoglobin, so it travels further into tissue. This makes it a common choice for deeper musculoskeletal structures, such as muscles and joints.
980 nm: water and haemoglobin
At 980 nm, absorption by water and haemoglobin increases. In multi-wavelength systems it is used in advanced deep-tissue protocols, where it is associated with microcirculation and oxygen delivery. Because more energy is absorbed, technique and dose control are especially important.
Why independent control matters
Tissue type, depth and the clinical picture vary from patient to patient. A system that lets the clinician run one wavelength, any pair, or all three, and set each channel separately, allows the light to be matched to the case rather than using a single fixed setting.
VOLTA F3 combines 650 nm, 810 nm and 980 nm in one Class 4 platform, with independent control of each wavelength and built-in protocols that the clinician confirms or adjusts. Read more on the VOLTA F3 page and in our technology overview.
Dose: the other half of the equation
Wavelength decides where the light goes. Dose decides how much energy arrives. Photobiomodulation research describes a biphasic dose response: too little energy may produce no measurable effect, while too much may reduce the response. Dose is usually described in joules and joules per square centimetre, and depends on power, time, area and technique.
This is why structured protocols and training matter. Our Class 4 vs Class 3B guide explains how output power affects the time needed to deliver a planned dose.
This article is general educational information for healthcare professionals. It is not medical advice and does not make claims about treatment outcomes. Whether photobiomodulation is appropriate for a specific patient is a decision for the treating clinician. VOLTA F3 is registered with the Medical Device Authority, Malaysia (MDA registration GC6440126-238777) and is intended for use by qualified healthcare professionals.
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