Guide · Comparing lasers
Diode vs alexandrite laser hair removal: wavelength, skin type, speed, comfort and the evidence
Diode and alexandrite are both proven hair removal lasers, and in side-by-side trials they have produced similar long-term results. What separates them is wavelength, how your skin's own pigment competes for the energy, and how the machine is set. Here is how they compare, with Nd:YAG and IPL alongside.
Written & medically reviewed by Dr Sin Yong · 9 October 2026
Quick answer
- Diode vs alexandrite laser hair removal comes down to wavelength more than brand. Alexandrite emits 755 nm, which melanin absorbs strongly; hair removal diodes usually emit about 800–810 nm, a middle wavelength. Nd:YAG, at 1064 nm, is absorbed least by skin pigment.
- In underarm trials the two gave similar long-term results: 85% and 84% hair reduction a year after four sessions in one study, and no significant difference at six months in another. The Cochrane review found about 50% short-term reduction with each.
- Alexandrite tends to suit lighter skin and finer dark hair; diode is used across a broad range of skin types with careful settings; brown or tanned skin is usually safer with 1064 nm Nd:YAG. Comfort and speed depend on technique, spot size and cooling as much as on the laser type.
- At SkinRev Lab, Dr Sin Yong performs laser hair removal on the Lutronic Clarity II, which has 755 nm alexandrite and 1064 nm Nd:YAG rather than a diode, and chooses the wavelength area by area. It is priced at consultation.
Short answer
Diode vs alexandrite laser hair removal: the short version
Both are long-pulsed lasers that heat the pigment in hair so the heat damages the follicle, and both have trial evidence behind them. The differences are wavelength, how strongly skin pigment competes for the energy, and how a particular machine is built and set, rather than one being superior across the board.
The practical question is not which laser is better in general, but which wavelength suits your skin and hair in each area, and who sets the machine. The table compares the three common hair removal lasers and IPL.
| Alexandrite | Diode | Nd:YAG | IPL | |
|---|---|---|---|---|
| Light | 755 nm, single wavelength | Usually about 800–810 nm, single wavelength | 1064 nm, single wavelength | Broad band of light through a filter; not a laser |
| Absorption by melanin | Strong | Moderate | Lowest of the three lasers | Varies with the filter |
| Generally suits | Fair to light-brown skin with dark hair, including finer hair | A broad range of skin types with careful settings | Tanned and darker skin with coarse dark hair | Fair to light-brown skin with dark hair |
| Main caution | Tanned or darker skin absorbs more of the energy | Higher energy can increase pain and blistering | Weaker on fine or light hair; often felt as more painful | Results and safety depend heavily on the settings |
| Grey or white hair | Not effective | Not effective | Not effective | Not effective |
The names
What 'diode' and 'alexandrite' actually describe
The names describe the laser source, not a treatment. Alexandrite lasers emit at 755 nm. Diode lasers used for hair removal usually emit around 800 to 810 nm, though the word 'diode' on its own does not tell you the exact wavelength. Nd:YAG lasers emit at 1064 nm.
What reaches your skin is a combination of wavelength, pulse length, energy, spot size and cooling. A diode or an alexandrite laser set too aggressively for the skin can burn it; either, set appropriately for the right skin, reduces hair.
Clinics also use labels such as SHR for a way of delivering energy, many low-energy passes, rather than a type of laser. If a price list names a technology, ask which wavelength will be used on your skin and who will set the machine.
Skin type
Wavelength, melanin and your skin type
Within this range, the shorter the wavelength, the more strongly melanin absorbs it. Alexandrite at 755 nm is absorbed strongly, which makes it efficient on dark hair, including finer hair, on lighter skin, but means tanned or brown skin takes up more of the energy at the surface. Diode at about 810 nm sits in the middle, and Nd:YAG at 1064 nm is absorbed least and reaches deepest.
For darker skin, the evidence favours longer wavelengths. A review of laser hair removal in darker skin types concluded that long-pulsed diode and Nd:YAG lasers are suited to these skin types when used with conservative energy, longer pulses and several treatments. A meta-analysis of skin types III to VI found outcomes broadly similar across lasers and IPL, with Nd:YAG causing less post-inflammatory hyperpigmentation than IPL.
In short: alexandrite suits lighter skin, diode is a middle option across a wide range, and Nd:YAG suits darker or tanned skin. On a single-wavelength machine, any adjustment for a different skin tone has to come from the settings alone.
Trials
What side-by-side trials found
In a 12-month study, 15 people with skin types I to V had their underarms treated side by side four times, one side with a 755 nm alexandrite and the other with an 800 nm diode laser. Hair reduction a year after the last session was 85% with alexandrite and 84% with diode. Participants strictly avoided tanning, which allowed relatively high energy even in skin type IV.
A study of 20 women with skin types I to IV compared long-pulsed diode and alexandrite on the underarms over three monthly sessions. Six months after the last session, hair reduction did not differ significantly between the lasers or the two energy levels, and partial regrowth within six months was typical. Pain and blistering were rare with either, but more frequent with the diode at the higher energy.
A third trial treated four quadrants of the underarms with alexandrite, Nd:YAG, both combined, and diode. One to two months later, reduction was 70.3% with alexandrite, 59.7% with diode and 47.4% with Nd:YAG, and combining alexandrite with Nd:YAG added nothing. Follow-up was short, so this reflects early response more than lasting results.
The Cochrane review, which accepted only randomised trials, found about 50% short-term hair reduction with alexandrite and with diode up to six months, no trial documenting long-term removal, and no trial of high methodological quality. With small, short studies the norm, claims that one is clearly superior go beyond the evidence.
Speed
Speed: spot size and technique matter more than the label
How long a session takes depends largely on spot size, repetition rate and technique. A larger spot covers more skin with each pulse; some diode devices fire rapidly while the handpiece keeps moving; others use suction under a large spot. Alexandrite and Nd:YAG platforms also offer large spot sizes, so a large area is not automatically slower on them.
In a study of a large-spot diode with vacuum assistance, 35 people had three underarm treatments; hair clearance was 54% at six months and 42% at 15 months, and remaining hairs were thinner and lighter. In a randomised side-by-side comparison of two 810 nm diodes, a low-energy, multiple-pass in-motion technique and a high-energy single-pass technique gave similar reduction at six months, maintained at 12 months.
Speed matters for large areas such as the legs and back. For the underarms or upper lip, the difference is minutes. Faster should never mean more energy than your skin can take.
Comfort
Comfort: what the studies say about pain
Each pulse is felt, usually as a hot snap or prick. In the four-quadrant trial, participants found alexandrite and diode the more tolerable, and Nd:YAG and the combination the more painful. In the meta-analysis of skin types III to VI, lasers were rated more painful than IPL.
Technique changes comfort as much as wavelength. The in-motion diode was rated significantly less painful than the single-pass diode, an average of 2.7 against 3.6 on a 10-point scale, while in the diode–alexandrite study, pain and blistering were more frequent with the diode at higher energy. Skin cooling with every pulse, and numbing cream on small sensitive areas, make sessions easier to tolerate.
IPL
Where IPL fits
IPL, intense pulsed light, is not a laser. It fires a broad band of light through a filter, so part of the energy falls at wavelengths the hair does not need and the skin absorbs. In the meta-analysis of skin types III to VI, alexandrite reduced hair counts more than IPL, diode and Nd:YAG were not significantly different from IPL, and Nd:YAG caused less pigment darkening.
The Cochrane review found little evidence for an effect of IPL in the randomised trials available at the time. In Singapore, the National Environment Agency allows only registered medical practitioners to operate class 4 lasers, the category that covers clinic hair removal lasers, on people; IPL devices are not controlled in the same way. SkinRev does not offer IPL.
Choosing
Choose by your skin and hair, not the machine's name
Questions worth asking at any clinic: which wavelength will be used on each of my areas, who performs the treatment, will a test patch be done, and how will the plan change if hair returns?
Hormonal hair on the chin and jaw, or new hair growth with irregular periods, needs a medical look before any machine is chosen.
- Fair skin with dark hair, including finer hair: 755 nm alexandrite is usually efficient.
- Light-brown, untanned skin: alexandrite at conservative settings or a diode can both suit; naturally darker areas may need 1064 nm.
- Brown or tanned skin: 1064 nm Nd:YAG is usually preferred, with longer pulses and cooling.
- Fine, light hair: responds less to any laser; expect more sessions and a smaller change.
- Grey, white or red hair: no laser targets it reliably; electrolysis is the alternative.
At SkinRev Lab
What SkinRev Lab uses, and why
SkinRev Lab does not use a diode laser for hair removal. Dr Sin Yong performs laser hair removal on the Lutronic Clarity II, which carries both 755 nm alexandrite and 1064 nm Nd:YAG. With both wavelengths on one platform, fair forearms and darker underarms on the same person can each get the wavelength that suits them.
At consultation he looks at skin type in each area, hair colour and thickness, sun exposure, medicines and any treatment you have had elsewhere, and discusses the options, including waxing, shaving, electrolysis elsewhere for light hair, or no treatment. Treatment is priced at consultation, and results vary between people.
Laser hair removal is performed at SkinRev Lab, #B1-28 CityLink Mall, 1 Raffles Link, by City Hall and Esplanade MRT (daily 11am–8pm, WhatsApp +65 8266 9585), and at IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, Orchard (WhatsApp SkinRev Lab on +65 8266 9585 or IN Eternity Clinic on +65 8815 3008).
Sources
References & sources
- Eremia S, Li C, Newman N. Laser hair removal with alexandrite versus diode laser using four treatment sessions: 1-year results. Dermatol Surg. 2001;27(11):925-929.
- Handrick C, Alster TS. Comparison of long-pulsed diode and long-pulsed alexandrite lasers for hair removal: a long-term clinical and histologic study. Dermatol Surg. 2001;27(7):622-626.
- Khoury JG, Saluja R, Goldman MP. Comparative evaluation of long-pulse alexandrite and long-pulse Nd:YAG laser systems used individually and in combination for axillary hair removal. Dermatol Surg. 2008;34(5):665-670.
- Haedersdal M, Gøtzsche PC. Laser and photoepilation for unwanted hair growth. Cochrane Database Syst Rev. 2006;(4):CD004684.
- Dorgham NA, Dorgham DA. Lasers for reduction of unwanted hair in skin of colour: a systematic review and meta-analysis. J Eur Acad Dermatol Venereol. 2020;34(5):948-955.
- Koo B, Ball K, Tremaine AM, Zachary CB. A comparison of two 810 diode lasers for hair removal: low fluence, multiple pass versus a high fluence, single pass technique. Lasers Surg Med. 2014;46(4):270-274.
- Ibrahimi OA, Kilmer SL. Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal. Dermatol Surg. 2012;38(6):912-917.
- Battle EF Jr, Hobbs LM. Laser-assisted hair removal for darker skin types. Dermatol Ther. 2004;17(2):177-183.
Common questions
Your questions,
answered
Is diode or alexandrite better for laser hair removal?
Neither wins across the board. Side-by-side underarm trials found similar long-term hair reduction, 85% and 84% a year after four sessions in one study. Alexandrite suits lighter skin and finer dark hair; diode is a middle wavelength used across a broad range of skin types. The choice should follow your skin and hair.
Which suits Asian skin, diode or alexandrite?
It depends on the shade and the area. On untanned light-brown skin, either can suit with appropriate settings. On brown or tanned skin, and in darker areas such as the underarm and bikini line, the longer 1064 nm Nd:YAG wavelength is usually preferred.
Is diode laser hair removal less painful than alexandrite?
Not reliably. In one trial, participants found alexandrite and diode similarly tolerable and Nd:YAG more painful; in another, pain and blistering were more frequent with the diode at high energy. Low-energy, in-motion diode techniques were rated less painful than single-pass diode treatment.
Is diode laser hair removal faster?
Some diode devices are quick because of large spots, suction or in-motion techniques, but alexandrite and Nd:YAG platforms also use large spots. Speed depends on the device and technique more than on the laser type.
Is a diode laser safe for dark skin?
Long-pulsed diode lasers have been used on darker skin with conservative energy and longer pulses. Nd:YAG at 1064 nm is absorbed least by skin pigment and is usually the first choice for the darkest skin types.
How many sessions do diode and alexandrite need?
A course is needed with either, because only actively growing hairs respond at each visit. The trials above used three or four sessions, partial regrowth within months was common, and maintenance may be needed. Your plan is set at consultation.
Is IPL the same as a diode laser?
No. IPL is a filtered broad band of light, not a laser; a diode laser emits a single wavelength. In a meta-analysis of skin types III to VI, diode and IPL were not significantly different for hair reduction, while alexandrite outperformed IPL.
Does SkinRev Lab use a diode or an alexandrite laser?
Dr Sin Yong uses the Lutronic Clarity II, a dual-wavelength platform with 755 nm alexandrite and 1064 nm Nd:YAG, and chooses the wavelength area by area. There is no diode. Treatment is priced at consultation.
Do diode or alexandrite lasers work on grey or white hair?
No. Both target melanin, and grey, white, red and very fine blonde hair carry too little of it. Electrolysis, which treats one follicle at a time, is the method for light hair; SkinRev does not offer it.