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CW Fiber Lasers
Frequently Asked Questions
In fiber lasers the active gain medium is an optical fiber doped with rare elements. A pump source, typically a laser diode is coupled into the core of a doped optical fiber where stimulated emission occurs. Doping the optical fiber with rare earth element such as ytterbium, erbium, holmium, etc. creates the medium where population inversion is enabled and where light amplification by stimulated emission occurs. The light generated is then amplified upon thousands of reflections off the nodes of a fiber Bragg grating which acts as the “cavity mirrors” similar to that of a traditional free-space laser. Fiber Bragg grating acts as the optical filter allowing reflection of only specific modes in the laser cavity.
Fiber Bragg grating (FBG) is a periodic structure (segment of periodic variation of optical index) created inside the fiber core that causes the light to diffract, reflect or transmit based on the phase and wavelength. These periodic structures applied to the core of the optical fibers are typically a few millimeters or centimeters long with a period that is on the order of a wavelength or hundreds of nanometers. FBG acts as an effective optical filter in fiber optic devices including fiber lasers.
Single-mode and multimode fibers are both used in designing and producing fiber lasers. However, single-mode fiber lasers tend to be more efficient and have a higher beam quality. Not to mention that single-mode fiber lasers do not suffer from mode hopping. In particular, ultra-narrow linewidth fiber lasers are constructed of single mode fibers doped with rare elements.
Supercontinuum generation exploits the nonlinear effects of certain optical media. Therefore, the fibers used in supercontinuum lasers are made of strongly nonlinear materials. These fibers will also need to provide good transmission throughout the entire amplification bandwidth. Fluoride based optical fibers are often used in supercontinuum fiber lasers.
While free-space lasers can last up to 15 years, fiber lasers enjoy a much longer lifespan which could reach 45 years or the equivalent of 100,000 hours of operation. This longevity is thanks to the compact sealed design that has fully integrated cavity without any free space intracavity optics that exists in other DPSS lasers.
Owing to their strong power output, CW fiber lasers are widely used in laser machining applications such as laser cutting, drilling, marking, and welding. They are also used in many research areas to perform precision measurements, spectroscopy, laser pumping, and optical testing.
You are probably referring to the external fiber that couples the laser output to other devices. Typically, the fiber length ranges between 0.5 and 1m in fiber lasers. However, the fiber end is attached to a connector which makes it very easy and simple to connect to other fibers if needed. The length of the optical fiber inside the cavity is fixed and determines the amplification gain.
Some units offer a tunable wavelength feature which allows the user to select a wavelength out of a few options. Supercontinuum fiber lasers can be used along with a bandpass filter to filter out the desired wavelength as well.
Many suppliers of CW fiber lasers offer models with both linear and random polarization. Less frequently, circular polarization is also an available option on market from many suppliers.
CW Fiber Lasers: The Continuous Power Behind Precision Applications
Continuous Wave (CW) fiber lasers are an essential technology in the modern photonics landscape. Unlike pulsed lasers, which emit bursts of light, CW fiber lasers provide a steady, uninterrupted laser beam. This continuous output is indispensable for applications that require consistent energy delivery, such as precision welding, cutting, thermal processing, and scientific experimentation.
What Is a CW Fiber Laser?
A CW fiber laser generates a laser beam that maintains a constant optical output over time. This is achieved by exciting rare-earth dopants (commonly ytterbium, erbium, or thulium) embedded in an optical fiber using diode lasers. The result is a highly efficient and compact system with outstanding beam quality and thermal management.
The fiber-based structure allows the laser to be coiled, cooled, and integrated into tight spaces—offering great flexibility and ease of use compared to bulkier laser systems. The fiber acts as both the gain medium and waveguide, ensuring stable beam propagation and minimal signal loss.
Advantages of CW Fiber Lasers
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High Beam Quality
CW fiber lasers produce diffraction-limited beams, which means cleaner cuts, finer welds, and more precise results across applications. -
Scalability
Easily scaled from a few watts to multi-kilowatt systems for different power needs. -
Energy Efficiency
With wall-plug efficiencies exceeding 30–40%, these lasers are more energy-conscious than traditional gas or solid-state lasers. -
Compact and Robust Design
All-fiber design ensures fewer alignment issues, better thermal dissipation, and less downtime. -
Low Maintenance
Fiber lasers have no moving parts, making them highly durable and nearly maintenance-free.
Applications of CW Fiber Lasers
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Industrial Manufacturing
The largest domain for high power CW fiber lasers, manufacturing benefits from their ability to cut, weld, drill, and scribe a variety of materials with precision. Metals like stainless steel, aluminum, and titanium are routinely processed using these lasers. -
Medical and Biomedical
CW lasers are used for photocoagulation, surgical cutting, and thermal ablation. Their stable output allows controlled tissue interaction with minimal collateral damage. -
Defense and Aerospace
In defense, CW lasers are explored for applications like directed energy weapons and countermeasure systems. Their ability to deliver constant power makes them viable for target illumination and destruction. -
Scientific Research
Laboratories use CW lasers for optical trapping, Raman spectroscopy, and frequency doubling experiments, where stable, continuous light is essential for data integrity. -
Telecommunications
While pulsed lasers often dominate short bursts of data transmission, CW lasers still play a role in pumping optical amplifiers and in certain coherent communication systems.
The Future of CW Fiber Lasers
As industry demands increasingly high power CW lasers for advanced applications, fiber laser technology is evolving rapidly. Innovations in cooling, fiber core design, and wavelength tunability are opening up new possibilities—from ultrafast materials processing to quantum communication.
Moreover, integration with robotics and AI-based automation systems is allowing CW fiber lasers to reach new heights in smart manufacturing. Their modular design and digital control interfaces make them easy to deploy, monitor, and optimize in real-time.
Conclusion
CW fiber lasers are no longer just tools—they’re critical enablers of precision, speed, and efficiency across a vast spectrum of industries. From high-power industrial cutting to delicate medical procedures and cutting-edge research, the continuous and clean output of CW fiber lasers positions them as cornerstones of the photonics revolution.
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Did You know?
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2 - 7 Advantages of Fiber Lasers
3 - Researchers Present A New Approach to Ultrafast Fiber Lasers
4 - Narrow Linewidth Lasers: Buyers Guide