A fiber laser is a laser that has an optical fiber doped with rare earths, which is used as a gain medium. Laser light is generated and amplified through the activation of the optical fiber. This type of laser has many unique advantages, which is why it is widely used in the medical and industrial sectors.
1. Operational Principle
The nature of a fiber laser is that it uses optical fiber as its medium for amplification. It is an active element requiring electrical power (as other active elements in electronics), making use of ig light amplifying properties of the rare earth ions. A laser light source (diode laser) is pumped into the fiber optic via a coupler, and as a result the rare earthed elements are energized ‘to announce the presence of laser light through stimulated emission phenomena. The laser light is amplified successively and propagated along the optical fiber and output at the end of the fiber.
2. Basic Structure of a Fiber Laser
A fiber laser typically consists of the following main components:
Pump Source
This is the laser’s “energy source.” A high-power semiconductor laser diode (LD) is typically used as the pump source, exciting rare-earth ions in the fiber from the ground state to an excited state.
Doping Light
The doped core component is typically ytterbium (Yb)-doped double-clad fiber. The outer layer drives the pump light, while the inner layer forms the laser gain region, completing the excitation radiation step.
Fiber Bragg Grating (FBG)
This is equivalent to the “mirror” of a traditional laser. A pair of fiber Bragg Gratings (FBGs) act as total and partial reflectors, respectively, combining to form an optical cavity, repeatedly amplifying the light and ultimately transmitting the laser beam.
Output Fiber Optic System
Laser output via optical fiber can be directly connected to a processing head or scanning system for various applications such as cutting, welding, and marking.
3. Advantages
- High Quality of Beam: The beam produced by the fiber laser is characterized by high quality and low divergence of the beam.
- High Efficiency: The efficiency of the optical-to-electrical conversion of fiber lasers is very high, usually ranging from 30% to 50%.
- Good Heat Dissipation: The large surface area of the optical fiber facilitates heat dissipation and allows fiber lasers to work in the continuous operating area of high power.
- Compact and Robust: Fiber lasers are small in size and also possess a high feature of stability and shock resistance.
- Maintenance Free: Due to their construction (solid state, sealed), fiber lasers normally have a long life and relatively no maintenance.
- Tunability: The power, as well as the wavelength of fiber lasers is a variable over a certain limit to the requirements of different technical solutions.
4. Applications
- Minimally Invasive Surgery: Fiber lasers are delivered to the interior of the body by the optical fiber and so are used in minimally invasive surgery such as endoscope surgery.
- Cutting and Coagulating Tissue: They are suitable for cutting and coagulating tissues in surgical procedures decreasing blood loss and improving healing time.
- Skin Treatment: They are good for laser hair removal, skin rejuvenation and removal of pigmented lesions.
- Ophthalmic Surgery: The highly controlled beam is good for retinal surgery as well as laser myopia correction surgery.
- Tumor Treatment: Laser light is beamed to the site of the tumor via fiber optic for photothermic treatment.
5. Safety Precautions
- Cooling System: Although fiber lasers do indeed have good heat dissipation, high power applications still require good cooling system.
- Fiber Quality: The quality and pureness of the fiber are directly connected to the performance and life of the laser equipment.
- Laser Safety: The high power output of the fiber laser equipment requires strict adherence to laser safety measures for protection of both operators and patients.
Summary
Fiber lasers with their high efficiency, high beam quality, good heat dissipation and versatility have become indispensable in the medical field. It is essential in selecting and using a fiber laser that its performance, reliability and safety be assured according to the specific medical application requirements. Learn more about our fiber laser systems.
