The core principle of diode lasers is “selective photothermolysis.”

Light absorption: The device emits coherent light of a specific wavelength (typically 808nm/810nm, with some advanced devices covering 755nm/808nm/1064nm). This wavelength of light penetrates deep into the skin and is highly absorbed by melanin in the hair follicles.

Photoenergy to heat: After absorbing the light energy, the melanin instantly converts it into heat.

Follicle coagulation: The heat is conducted to the hair follicle’s germinal center (dermal papilla and hair follicle stem cells). When the temperature rises to a certain threshold, the hair follicle tissue undergoes irreversible coagulative necrosis.

Long-term inhibition: Damaged hair follicles lose their regenerative capacity, thus achieving a long-term hair reduction effect.