Solid-state lasers are currently the most widely used and mature medical lasers. The typical solid-state medical laser is the Nd:YAG laser, which is the neodymium-doped yttrium aluminum garnet laser. The main operating wavelength is 1064 nm. For scalpel applications, continuous output is generally used, and the power is about tens of watts; for dermatological pigment disease treatment, Q-switched output is often used, the energy can reach 1 joule per pulse, and the pulse width can be as narrow as a few nanoseconds. It can also be used for Inner eye surgery such as membranous cataract, lens capsulotomy, iridotomy, lens and vitreous cord cutting in the anterior chamber.

When this type of laser is output as a long pulse, it can also be used to remove hair, and the pulse width can be as long as 200 ms; as a free oscillation mode, it can be used for the treatment of chronic tear duct obstruction in ophthalmology. In addition, the frequency-doubled 532 nm wavelength laser of Nd:YAG laser also has important applications in many treatment fields, such as ophthalmology, dentistry, dermatology, prostate resection, etc., and can be used for symptomatic treatment of dermatological wrinkles and hair removal. Treatment and fundus disease treatment, etc.

The other wavelength of the Nd:YAG laser is 1320 nm, which is suitable for the treatment of large and small saphenous varicose veins and non-functional superficial branch varicose veins caused by blood reflux. The 1.3 μm laser output by the Nd:YAP (neodymium-doped yttrium aluminate) laser is similar to this wavelength. Due to its relative safety to the human eye, this wavelength laser has been widely used in medical surgeries and can be used to remove dental caries. And treatment of pulp cavity preparation, dentin hypersensitivity, gingival tumor and hemangiomas removal, external irradiation of oral ulcers, etc.

In recent years, the emergence and development of mid-infrared solid-state lasers with wavelengths above 2 mm have provided a large number of new ideal options for laser medicine, such as typical YAG lasers doped with holmium, thulium and erbium. Most of these lasers work in pulse mode. The wavelength of Ho:YAG (holmium-doped yttrium aluminum garnet) laser is 2.1 μm, which is suitable for contact and non-contact cutting, resection and coagulation of soft and hard tissues, such as for urinary tract stones; Dermatology treats pyogenic granuloma, senile warts, and senile keratosis; obstetrics and gynecology treats cervical erosion; otolaryngology treats nasal polyps and throat papillomas; lumbar disc percutaneous surgery, etc.; this laser system is used in percutaneous myocardial surgery Vascular reconstruction, as an ideal instrument in angioplasty, is known as "the fourth milestone in the treatment of coronary heart disease."

The 2.0 μm wavelength output by the Tm:YAG (thulium-doped yttrium aluminum garnet) laser is similar to the Ho:YAG laser and can be used for contact and non-contact cutting, resection and coagulation of soft and hard tissues.

Another type of Er:YAG (erbium-doped yttrium aluminum garnet) laser has an output wavelength of 2.9 μm. Since water strongly absorbs this wavelength, it is mainly used for laser treatment of shallow tissues, such as punching blood, ophthalmic treatment, and tenderness. Skin surgery, etc. In addition, it is also used in other fields such as otolaryngology and tumor treatment. Its treatment principle can basically be attributed to the laser scalpel. Similarly, there is the so-called "water laser" (Er,Cr:YSGG laser, named because it uses water to guide light), which has a wavelength of 2780 nm and is used in dentistry.

Some early solid-state lasers, such as ruby lasers with a wavelength of 694.3 nm and alexandrite lasers with a wavelength of 755 nm, were used as the earliest laser medical devices for skin pigmentation removal, skin hair removal, tattoo removal, and treatment of benign skin pigmented lesions. aspect.

In recent years, with the continuous emergence of advanced laser devices with comprehensive performance, this type of laser has gradually withdrawn from the field of medical lasers. It is worth mentioning that the femtosecond titanium-doped sapphire laser currently widely used in scientific research not only has a broadband spectrum including the above-mentioned wavelengths and wavelength tuning capabilities, but also has a pulse width of less than 100 fs, which is excellent in disease diagnosis and precision surgery. more and more widespread applications.

Another trend in medical lasers is fiber laser. As a type of solid laser, fiber laser not only covers the wavelengths of commonly used solid medical lasers such as 1.064 mm, 1.3 mm, 1.5 mm and 2 mm, but also femtosecond Rapid progress has been made in ultra-short pulse, high-power output and other operating modes. It is foreseeable that fiber lasers will account for an increasing share of medical lasers in the future.

Carbon dioxide laser, output wavelength 10.6 μm, is a far-infrared laser. It has two working modes: continuous and pulse. In clinical practice, it is generally transmitted through a light-guiding joint arm. Because carbon dioxide laser is easy to achieve high-power output (above kilowatts), the cost is relatively low, and its wavelength has extremely high absorption rate for water, it is mostly used for intense laser treatment.

Helium-neon laser, output wavelength is 632.8 nm. It is mainly a continuous working mode with a power of only 10 mW. It can only be used for weak laser treatments, namely laser physiotherapy and laser acupuncture; it can also be used as a therapeutic light source for photodynamic therapy.

Argon ion laser, the main output wavelength is 514.5 nm and 488 nm, continuous working mode, the power can reach tens of watts. This laser has a short working life and high operating costs. In principle, it costs a lot to replace the laser tube every 3 to 4 years. Its visible blue-green wavelength laser can be transmitted through optical fibers. Hemoglobin has a very high absorption rate at this wavelength and can be used as a therapeutic light source for photodynamic therapy.

Similar to it is the copper vapor laser. At present, the frequency-doubled Nd:YAG laser pumped by a diode laser can obtain a 532 nm green laser with an average power greater than 10 W in continuous operation and an average power greater than 100 W in high repetition frequency operation. Therefore, it can not only be used in many medical aspects It replaces argon ion laser and copper vapor laser, and has new applications in ophthalmology, prostate, etc., and shows strong economic practicability.

Krypton ion laser, the main operating wavelengths are 406.7 nm, 415.4 nm, 568 nm, and 647 nm. Mainly for continuous working mode. Can be used as a diagnostic light source for photodynamic therapy.

Helium-cadmium laser, output wavelength 441.6nm. Mainly for continuous working mode. Can be used as a diagnostic light source for photodynamic therapy.

Currently, there are many options for the output wavelength of semiconductor lasers from 405 nm to 1500 nm, and the working modes include continuous and pulse operation. Generally, the wavelength and working mode are used to define the name, such as: 630 nm continuous semiconductor laser, 780 nm pulse semiconductor laser, etc.; semiconductor materials are also used to directly define the name, such as: gallium arsenide semiconductor laser, arsenic aluminum gallium semiconductor laser, etc.

Dye laser can be said to be the laser with the widest wavelength coverage. Selecting different dyes can achieve tuned output from 400 nm to 950 nm. The main working methods include continuous wave and pulse wave. According to different pumping methods, they are divided into flash pumping and Laser-pumped dye lasers. Dye laser combined with frequency-doubled Q-switched Nd:YAG laser can be used to remove tattoos, treat vascular and pigmented lesions, cut, excise, ablate and vaporize soft tissue in general dermatology, and remove excess human hair.