What Is The Difference Between Fiber Laser And Diode Laser?

Fiber Lasers and Diode Lasers are two common types of lasers, and they differ in structure, performance, etc. Fiber lasers and diode lasers are widely used in modern industry, medical and scientific research fields. Both laser technologies use rare earth element-doped glass fibers or semiconductor materials as gain media to produce lasers of different wavelengths and powers.

Fiber laser is a solid laser technology that uses glass fiber doped with rare earth elements such as erbium, ytterbium, and neodymium as the active medium. This laser's beam is generated inside the optical fiber and then transmitted through the flexible fiber, thus providing excellent beam quality and stability. High efficiency and excellent beam quality are the main advantages of fiber lasers, making them widely used in laser fiber communications, laser space long-distance communications, industrial shipbuilding, automobile manufacturing, laser engraving, laser marking, laser cutting, printing rollers, metal and non-metallic applications. It is widely used in many fields such as metal drilling/cutting/welding.

Diode lasers are solid-state laser devices based on semiconductor materials. Their working principle mainly relies on the function of p-n junction and current injection. Compared to fiber lasers, diode lasers have a smaller output power range, but their wider wavelength range allows for greater flexibility. In addition, diode lasers are also widely used in fields such as communications and data transmission, printing and engraving, display and lighting.

The difference between fiber lasers and diode lasers
1. Working principle
Fiber lasers transmit energy through optical fibers and generate laser light in the optical fibers. Its laser output quality is high, the beam quality is good, the power is high, and the heat dissipation system design is relatively complex.
Diode lasers convert electrical energy into light energy through semiconductor materials. Their output wavelength is single and the beam quality is poor, but it has the advantages of being affordable and easy to use.
2. Structure
The structure of fiber laser is complex, including fiber, pump light source, cooling system, etc.
The structure of a diode laser is relatively simple, mainly including a diode, an external cavity, a pump light source, etc. Fiber lasers are generally bulky in terms of size and weight, while diode lasers are smaller and lighter.
3.Performance
Fiber lasers have the characteristics of high power, high efficiency, and high-quality beams. Their output wavelengths cover a wide range and have good spot quality. They are suitable for manufacturing, scientific research and other fields.
Diode lasers are mainly suitable for some conventional applications, such as fiber optic communications, laser printing, phototherapy, etc. Diode lasers are cheap, easy to use, and suitable for some organizations or individuals with a lower budget.

Feature comparison
A. Output power
Fiber lasers generally have a wide output power range, ranging from a few hundred watts to several kilowatts. For example, IPG's high-power continuous fiber lasers can provide output powers from 1 kW to over 100 kW. In addition, fiber lasers have a wide operating wavelength range, can choose single mode or multi-mode, and have high stability and long life pump diodes.

As for diode lasers, their output power range is generally lower, ranging from a few watts to hundreds of watts. This is because the working material of the diode laser is a semiconductor material, and the number of photons generated by its energy level transition is relatively small, so the output power is relatively low. However, diode lasers have the advantages of wide variety of wavelengths, small size, and high efficiency, so they still have unique advantages in some specific applications.
B. Wavelength range
The wavelength range of fiber lasers depends primarily on the gain medium used. For example, the absorption spectrum of ytterbium-doped fiber (YDF) ranges from 900nm to 1000nm, with two strong absorption peaks at 915nm and 976nm. Therefore, the output wavelength of ytterbium-doped fiber lasers is usually in the near-infrared region, such as the 1 μm band.

The wavelength range of diode lasers is relatively wide, from visible light to near-infrared light. The specific wavelength depends on different semiconductor materials and structural designs. For example, semiconductor lasers using different materials can produce lasers with different wavelengths such as 800nm, 940nm, 1310nm, and 1480nm.
C. Beam quality
Fiber lasers typically have very high beam quality and can produce near-diffraction-limited beams. Specifically, the key parameter of its beam quality is BPP (Beam-parameter product), which can directly affect the quality of precision machining and macro machining. For example, it can be used to cut, weld or process a variety of materials, including thin sheets and reflective metals. Additionally, due to their high power density, fiber lasers enable faster processing and increased productivity.

The beam quality of diode lasers depends on the specific type. The simplest case is a VCSEL (Vertical Cavity Surface Emitting Laser), which typically emits a beam with high beam quality, moderate beam divergence, no astigmatism and a circular intensity distribution. However, if a simple spherical lens is used, the coupling efficiency is significantly reduced due to the ellipticity of the beam. Another example are small edge-emitting laser diodes, which also emit in a single spatial mode and therefore in principle also allow efficient coupling to single-mode fibers.
D. Efficiency and energy consumption
Fiber lasers have excellent electro-optical conversion efficiency and can convert a larger proportion of input electrical energy into laser output. This is mainly due to the special structure of its gain medium, that is, ytterbium-doped fiber. In addition, fiber lasers have excellent beam quality, producing near-diffraction-limited beams, resulting in improved processing accuracy and capabilities. The high power density of fiber lasers enables rapid processing and increased productivity.

As for diode lasers, their efficiency and energy consumption vary depending on the specific type. For example, VCSELs (Vertical Cavity Surface Emitting Lasers) can emit beams with high beam quality, moderate divergence, no astigmatism and a circular intensity distribution. However, if a simple spherical lens is used for coupling, the coupling efficiency may be significantly reduced due to the ellipticity of the beam. As with small edge-emitting laser diodes, this diode also emits in a single spatial mode, thus in principle also allowing efficient coupling to single-mode fibers. In general, both fiber lasers and diode lasers have their own unique advantages and application values. For specific application requirements, the most appropriate laser type needs to be selected based on the specific situation.

Application
A. Application fields of fiber lasers
Fiber lasers are used in a wide range of applications, including industrial processing and manufacturing, the medical and cosmetic industries, as well as scientific research and military applications. In the industrial field, different types of fiber lasers have different typical applications. For example, it can be used for laser optical fiber communications, laser space long-distance communications, industrial shipbuilding, automobile manufacturing, laser engraving, laser marking, laser cutting, printing rollers, metal and non-metal drilling/cutting/welding (such as copper welding, quenching, cladding and deep welding), military defense and security, medical equipment and equipment, and large-scale infrastructure. In addition, fiber lasers can also be used as pump sources for other lasers.
B. Application areas of diode lasers
As a laser that uses semiconductor materials as working substances, diode lasers have a wide range of applications. In terms of communication and data transmission, it can be used in the construction of optical communication systems and directly used as a light source to convert electrical energy into laser. In addition, printing and engraving are also important application areas. Diode lasers are also widely used in the display and lighting fields, mainly due to their small size, high efficiency and long life.

Differences and characteristics of fiber lasers and diode lasers
The main differences and characteristics of fiber lasers and diode lasers can be compared in terms of their laser beam quality, light source, cutting efficiency, laser modules, system maintenance and power output.

Fiber lasers use rare earth element-doped glass fibers as gain media, which can be developed on the basis of fiber amplifiers to form high power density, causing "particle number inversion" of the laser energy level of the laser working material. When a positive feedback loop is appropriately added (constituting Resonant cavity) can form laser oscillation output. Therefore, it has high average power and strong thermal effect, and is widely used in metal material cutting, welding, drilling, sintering, etc. in the field of macro processing.

Diode lasers have the characteristics of high peak power, small thermal effect, and high processing accuracy. They are generally used in the field of fine micromachining of thin, brittle materials and non-metallic materials. The simplest case is a VCSEL (Vertical Cavity Surface Emitting Laser), which typically emits a beam with high beam quality, moderate beam divergence, no astigmatism and a circular intensity distribution. If a simple spherical lens is used, the coupling efficiency is significantly reduced due to the ellipticity of the beam. In addition, diode lasers have some problems such as astigmatism in the output, especially gain-guided diodes, which can be compensated for by additional weak cylindrical lenses.

Overall, the choice of which type of laser technology depends on the specific application needs and scenarios.

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