The lifespan of fiber lasers is quite remarkable. Most fiber lasers have a basic lifespan of over 100,000 hours. However, during daily operation, it is crucial to pay attention to maintenance. Any neglect may cause damage to the laser, which in turn can affect its service life. An external circulating water cooler plays an important role for fiber lasers. It provides excellent heat dissipation and cooling functions, contributing significantly to extending the lifespan of fiber lasers. In some cases, fiber laser temperature is too high, there are two main reasons. One is not configured for fiber laser cold water, need to configure the appropriate chiller cooling. Second, the configuration of the chiller cooling capacity is not enough to achieve effective cooling, it is recommended to replace the chiller to meet the cooling needs of the laser.
Fiber lasers possess several distinct advantages when compared to conventional lasers:
1. Superior Beam Quality
The waveguide structure of the fiber enables fiber lasers to easily obtain a single transverse mode output. Moreover, they are minimally affected by external factors, allowing them to achieve high-brightness laser output. This characteristic makes fiber lasers highly suitable for applications that demand high precision, such as in microfabrication and medical procedures.
2. High Efficiency
Fiber lasers employ semiconductor lasers as pump sources, carefully selected to match the emission wavelength with the absorption characteristics of the doped rare earth elements. This matching enables the achievement of a remarkably high light-to-light conversion efficiency. For ytterbium-doped high-power fiber lasers, semiconductor lasers with wavelengths of 915 nm or 975 nm are commonly chosen due to their long fluorescence lifetimes and the ability to effectively store energy for high-power operation. Commercially available fiber lasers can achieve an overall electro-optical efficiency as high as 25%, which not only helps in reducing costs but also promotes energy conservation and environmental protection.
3. Excellent Heat Dissipation Characteristics
Fiber lasers utilize a thin, rare earth element-doped fiber as the laser gain medium. This type of fiber has an extremely large surface area to volume ratio, which is approximately 1000 times that of solid block lasers. This inherent characteristic gives fiber lasers a natural advantage in heat dissipation capabilities. In low and medium power applications, the fiber typically does not require special cooling. For high-power applications, water cooling can be employed, effectively preventing the degradation of beam quality and efficiency caused by thermal effects, which are common issues in solid-state lasers.
4. Compact Structure and High Reliability
Fiber lasers use small and flexible fibers as the laser gain medium, which is beneficial for reducing the overall volume and saving costs. The pump source is also based on small-sized, easily modular semiconductor lasers. Commercial products usually come with pigtail output. When combined with fiber optic devices such as fiber Bragg gratings, by fusing these devices together, a fully fiberized system can be achieved. This system has a high level of immunity to environmental perturbations, ensuring high stability and saving both maintenance time and costs.
The Structure of Fiber Lasers
The generation of laser signals requires three fundamental conditions: the inversion of the number of particles, the presence of optical feedback, and the attainment of the laser threshold. As a result, a laser is composed of three main parts: the working material, the pump source, and the resonant cavity. The basic structure of a fiber laser is as follows: The gain fiber serves as the gain medium for generating photons. The pumping light acts as an external energy source, enabling the gain medium to achieve a particle number inversion, which is provided by the pump source. The optical resonant cavity consists of two mirrors, whose function is to allow photons to receive feedback and be amplified within the working medium. When the pumping light is absorbed by the gain fiber, it causes a particle number inversion in the energy levels of the gain medium. When the gain within the resonant cavity exceeds the loss, laser oscillations are formed between the two mirrors, resulting in the output of a laser signal.
Fiber lasers have a wide range of applications in medical equipment. Here are some common areas:
- Soft Tissue Surgery: In surgical procedures related to the ear, nose, and throat (ENT), urology, and cardiovascular surgery, fiber lasers can be utilized as laser scalpels. Leveraging their high-power and high-quality characteristics, they can achieve precise cutting. Additionally, their good thermal control performance minimizes damage to the surrounding tissues.
- Ophthalmic Treatment: High-power erbium-doped fiber lasers are applicable for cataract treatment. By using low-power infrared lasers, they can rapidly vaporize and peel off the cloudy membrane, restoring the transparency of the lens. In the treatment of glaucoma, lasers with appropriate wavelengths and energies can create microchannels, facilitating the flow of fluid in the eye and restoring vision.
- Dermatology Treatment: The 1550nm non-exfoliative fractional erbium laser can accurately target specific tissues and heat the water content in the dermal collagen tissues. It is used for skin rejuvenation, wrinkle removal, acne scar repair, and other applications, delivering favorable therapeutic results. Moreover, the 2910nm erbium glass fiber laser can be employed to improve skin photodamage, featuring a short treatment time and minimal side effects.
- Periodontal Disease Treatment: A semiconductor laser with a wavelength of 980nm exhibits excellent bactericidal effects on inflamed gum pockets. Using a laser for gum pocket scraping has a high success rate and causes minimal pain, offering an effective solution for treating various periodontal diseases.