Laser diode

What is the laser diode?

The diode is an electronic component that allows the flow of electric current in one direction and blocks it in the opposite direction.

It is a very important device in our daily life, used in electronic circuits of multiple devices and appliances, such as washing machines, televisions, computers, cell phones, etc.

The diode in esthetics

Applied to aesthetics, the diode laser is used, which behaves like a semiconductor, emitting light in a similar way to an LED.

It is made up of electrons and holes. From certain chemical processes, a current is generated that produces an emission of energy in the form of heat or ultraviolet radiation.

The laser can be directed to an exact location and regulate the power, which makes it a precise tool used in different areas of medicine.

In dermatology, the latter characteristic allows a depth of 2 mm to be reached. It passes through the epidermis and reaches the hair follicle (in the dermis), which is responsible for hair growth.

Therefore, the laser diode is more effective on darker skin, as the follicles are deeper due to a thicker epidermis.

Characteristics of the diode laser

The characteristics of the laser diode hair removal machines are decisive in establishing their effectiveness.


For the diode laser to do its job properly, the power applied is the key. This unit of measurement is expressed in watts (W).

Depending on the type of skin, it will be necessary to use more or less power to reach greater or lesser depth. For blacker and coarser hairs, more power is required.

Optimal power consumption should reach 800 W at least. The higher the power, the fewer hair removal sessions are needed, as the shots are more effective.


Power should not be confused with wavelength, which in the case of diode lasers is usually between 800 and 850 nanometers.

The wavelength determines the absorption and penetration of light into the skin. The longer the wavelength, the greater the penetration.


The diode laser hair removal equipment incorporates a cooling system in the heads, to be able to apply the indicated power on the skin without causing damage.

Good cooling systems allow the machine to be used without a break, so the sessions will be faster and painless.

In diode equipment, the contact system is usually used, in which glass or sapphire plates incorporated directly into the applicator are used.

Spot size

Spot size is very important in hair removal equipment. It is the size of the emitted light beam.

In other words, the larger the size, the larger the hair removal area covered by a single light pulse and the greater the penetration into the skin.

For example, Sisneo’s Twinscan equipment has a spot of 7.5 cm2. This size is larger than what is usually found on the market, allowing for faster and more energetic epilation.


Creep is used to measure the amount of energy that is sent to the treatment area. The question you should be asking yourself is not whether ipl or diode hair removal is best, but which works best for which skin and hair type. High-power equipment operates at 100 j/.cm².

The fluence, together with the power, allows to obtain a very high range of parameters to work with, depending on the type of hair and phototype.

When deciding between one equipment or another, it is important to take into account the fluence, but not as a decisive factor, but as a sum of parameters that make a hair removal machine good or not.

Pulse duration

The duration of the light pulse determines the effectiveness of the hair removal treatment.

If it is too short, it may cause damage to the tissues surrounding the area of action. Whereas if it is too long, it will not receive enough heat to destroy the hair follicle.

The ideal values are estimated to be between 4 and 100 milliseconds, in order to, together with the fluence, concentrate the energy and obtain results in a few sessions.

Laser diode contraindications

The diode laser has fewer contraindications than other hair removal methods.

In this case, it can act on tanned skin, as long as there has been no sun exposure for 48 hours before. Nor should there be during the following 48 hours.

It should also not be used on open wounds, as it could create unwanted scars on the dermis.

In addition, it is contraindicated in people who have received laser treatments within the last three months, who have suffered from herpes or people with photosensitivity.

In pregnant women, the use of laser is not recommended, since the hormonal changes suffered by women could cause an alteration in the function of the hair follicles and cause hair to grow where there was none before.


Commitment to quality

This text on diode laser has been written by professional editors and reviewed by Sisneo’s medical-aesthetic team. In addition, we have relied on experts in medicine, engineering and aesthetics as a source of information, as well as specific studies to maintain the quality of what we publish.

At Sisneo Bioscience we are committed to publish truthful and contrasted information. And to update or correct it as soon as new knowledge becomes available.