Fiber Lasers vs. Solid-State Lasers: What’s the Difference?

In today's rapidly changing laser technology, solid-state lasers and fiber lasers as the two mainstream laser products, each in industrial production, scientific research, military applications and other areas to show the unique charm and advantages.

First, the technical principle and performance differences

1. Gain medium

 

Fiber laser (Fiber Laser) is used as a rare earth element doped glass fiber gain medium. Under the action of pump light, high power density is formed in the fiber, resulting in the reversal of the number of particles in the laser energy level, and generate laser oscillations through the positive feedback loop of the resonant cavity. Fiber lasers are compact, do not require complex cooling systems, and the flexibility of the fiber makes it more advantageous in multi-dimensional spatial processing applications.

 

At the heart of a fiber laser is the optical fiber, a flexible, hair-thin glass or plastic filament known for its ability to direct light over long distances with minimal loss. This fiber acts as the active gain medium for the laser and is central to its operation. However, unlike undoped glass or plastic fibers used in telecommunications, the fibers in fiber lasers are doped with rare earth elements such as erbium or ytterbium. This doping introduces the energy states necessary for the laser to operate, allowing the fiber to not only direct light, but also amplify it.

 

Solid-State Lasers (SSLs) are centered on their unique gain medium, a solid material, and typically consist of four major components: the gain medium, the cooling system, the optical resonant cavity, and the pump source. The gain medium, such as ruby (Cr:Al₂O₃) or neodymium-doped yttrium-aluminum garnet (Nd:YAG), is the soul of the solid-state laser, and the activating ions doped inside it (e.g., Nd³⁺) are used to invert the number of particles in the pumping light to generate laser light. The cooling system is responsible for removing the heat accumulated inside the gain medium due to laser generation and ensuring stable operation of the laser. The optical resonant cavity creates a continuous oscillation through the positive feedback of photons to output a highly monochromatic and directional laser beam.

 

2. Performance and Efficiency

 

Fiber lasers are known for their exceptional electrical efficiency, thanks to the nature of fiber optic cables, which conduct light with minimal loss. This feature makes fiber lasers incredibly energy efficient, often achieving efficiencies in excess of 30%.

 

Solid-state lasers are typically less efficient, which can be attributed to the higher losses of their bulkier gain media and the need for high-intensity lamps for pumping.

 

3. Beam quality: directly affects the laser's effectiveness in precision applications.

 

The single mode operation of fiber lasers provides incredibly high beam quality, characterized by tight focus and minimal divergence.

 

Solid-state lasers, while capable of delivering high-quality beams, often struggle to match the beam quality of fiber lasers, especially at higher power levels.

 

Despite their lower efficiency and beam quality, solid-state lasers are not without their advantages. They have robust power scaling capabilities that make them well suited for high power applications. Solid-state lasers can be designed to produce incredibly high power levels by increasing the size of the gain medium and the pump power, which is not so simple for fiber lasers due to fiber size and heat dissipation limitations.

 

4. Stability

 

Fiber lasers are highly stable. Its fiber structure is insensitive to changes in the environment (e.g., temperature, humidity, vibration, etc.), and is able to maintain a stable working condition in harsher environments. At the same time, fiber lasers are considered to be more durable and adaptable to environmental changes because they have a solid-state structure and do not contain free-space optical components.

Solid-state lasers are relatively unstable and changes in environmental factors can have a significant impact on their performance.

 

5. Heat Dissipation Performance

 

Fiber laser has excellent heat dissipation performance. Its gain medium is an optical fiber, which has a large surface area to volume ratio, and the heat can be emitted quickly, so it can work stably for a long time and withstand a high power output.

 

Solid-state lasers are relatively difficult to dissipate heat and are prone to thermal effect problems during high power operation, affecting the performance and life of the laser.

 

6. Size and Maintenance Costs

 

Fiber lasers are very compact and require little maintenance. The small size of the fiber and the absence of external mirrors greatly reduces the alignment problems associated with solid-state lasers. In addition, the fiber's excellent ability to dissipate heat often eliminates the need for active cooling, further reducing maintenance requirements. Also, fiber lasers are typically safer to operate because the laser is confined within the fiber, reducing the risk of accidental exposure.

 

Alignment of the mirrors in solid-state lasers is critical to their operation and requires periodic checking and adjustment, which increases maintenance efforts. In addition, solid-state lasers typically require active cooling to manage the heat generated in the gain medium, which not only adds to the complexity of the system, but also increases maintenance requirements. Solid-state lasers tend to be larger than fiber lasers. The need for large gain intermediate and external mirrors increases their size and weight, limiting their suitability for space-constrained applications.

Application

Fiber lasers, on the other hand, shine in the field of industrial cutting and welding with their high power, high beam quality, good heat dissipation performance and stability. Fiber lasers are especially suitable for thick plate cutting and welding of metal materials, and their high electro-optical conversion efficiency and regulation-free, maintenance-free design greatly reduce the cost of use and maintenance difficulties. At the same time, the fiber laser's high tolerance for harsh working environments, such as dust, vibration, humidity, etc., also makes it perform well in all kinds of industrial sites. Continuous lasers have a high degree of penetration in the field of macro-processing, where they have gradually replaced traditional processing methods.

 

Solid state lasers are unique in the field of ultra-precision and ultra-micro processing with their high peak power, large pulse energy and short wavelength laser output (e.g. green, UV). In processes such as marking, cutting, drilling and welding of metallic/non-metallic materials, solid-state lasers are able to achieve higher processing precision and wider material applicability. Especially in the high-precision welding of non-metallic materials and light-curing 3D printing, solid-state lasers have become the preferred equipment by virtue of their short-wavelength lasers with small thermal effects and high processing precision. Solid state lasers are mainly used in the field of precision micromachining of non-metallic materials and thin, brittle and other metallic materials by virtue of their short wavelengths (ultraviolet, deep ultraviolet), short pulse widths (picoseconds, femtoseconds) and high peak power. In addition, solid-state lasers are widely used in cutting-edge scientific research in environmental, medical and military fields.

Market share

China is in the process of transformation and upgrading of manufacturing industry from low-end manufacturing to high-end manufacturing, the proportion of low-end manufacturing is high, and the macro-processing market covers both low-end manufacturing and part of high-end manufacturing, and the market demand is large, therefore, the market capacity of fiber lasers is large.

 

Domestic medium and low power fiber laser localization degree is high, domestic scale production manufacturers. According to the “China Laser Industry Development Report” shows that the low-power fiber laser has fully realized domestic substitution; medium-power continuous fiber laser, the domestic quality and its no obvious disadvantage, the price advantage is obvious, the market share is equivalent; high-power continuous fiber laser, domestic brands have achieved some sales.

 

As for solid-state lasers, due to the late development of the domestic, there is no listed companies with this product as the main business, generally buy foreign brands.

 

Fiber lasers are mainly used in the field of macro-processing by virtue of their high output power (laser macro-processing generally refers to the processing of dimensions and shapes where the laser beam affects the processing object in the range of millimeters); solid-state lasers are widely used in the field of microprocessing (microprocessing generally refers to the processing of dimensions and shapes where the precision reaches the micrometer or even nanometer level) by virtue of their short wavelengths, narrow pulse widths, high peak power, and other advantages The user of solid-state lasers and fiber lasers has some differences.

 

Generally speaking, solid lasers and fiber lasers have their own application areas. The two do not have direct competition in most of the fields, in the field of micromachining overlap in the field of metal materials processing, in the metal to a certain thickness of the case due to cost reasons the field generally use the traditional way or fiber lasers, only in the metal thickness of the thin or the processing of the requirements of the scene is not sensitive to the cost of the use of solid-state lasers. In addition, the degree of competition between the two overlap is low, solid-state lasers are mainly used in the processing of non-metallic materials (glass, ceramics, plastics, polymers, packaging, other brittle materials, etc.), and in the field of metal materials are used in the scenarios that require high precision and are relatively insensitive to cost.

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