Category: Wavelengths & Laser Types

Advancements in ultrafast fiber laser technology

Ultrafast fiber laser systems have reached a new level in modern technologies. And recently, a German company announced that they have developed a new fiber laser that has a perfect laser beam quality, high process technology, and could be bought with average powers of more than 100 W from stock.

Recent record in fiber laser performance

At the end of the 2018th, a team of researchers demonstrated their latest record that was a fiber laser system with 3.5 kW average power and a pulse duration of 430 fs after amplification. The laser system has an automated spatial and temporal alignment of the interferometric amplification channels.

Technical features of the new fiber laser

The novel fiber laser technology is based on an all-fiber amplifier that employs a coherent combination of four separately amplified laser beams. This fiber laser creates pulses of 1047 nm wavelengths and a repetition rate of 80 MHz. Then these pulses are divided into 4 separate laser beams and go into the amplifier.

Amplification process and plans

The point lies in the process of amplification, after which the fiber laser beam looks really nice. Nevertheless, the researchers are planning to increase the system to 10 kW later this year.

Advantages of ultrafast fiber lasers

At the same time, the laser systems have numerous advantages, such as:

• Efficient heat dissipation;
• Excellent output laser beam quality;
• Compactness and ruggedness;
• Reduced mode distortion;
• Reliable and low-cost technology;
• Fiber lasers ensure accurate cutting and a quite high edge quality;
• Laser modules can cut complex shapes in a short time.
• Laser systems meet all the manufacturing requirements.

All the mentioned benefits make fiber lasers an ideal solution for a lot of application fields, for example, precision engineering, including fiber laser micromachining, high precision sheet metal profiling, cutting transparent materials, marking components for traceability, gas and wind detection, oil and gas exploitation, pipeline integrity monitoring, perimeter security, and medicine etc.

Quantum coherence in ultrashort pulsed lasers

A team of researchers from five nations has introduced a new theory known as the coherent master equation, which examines the behavior of ultrashort pulsed lasers utilizing rapid materials and emphasizes the influence of quantum coherence. The quantum coherence of the pulsed laser is considered to be “the ability of material and light electrons to oscillate in unison for some time”.

Technological and scientific impact

These fiber laser systems allow emitting intense pulses of laser beam light of one billionth of a second at a constant rate, considerably influencing technology and science. This discovery promotes the development of new types of fiber lasers, especially with semiconductor materials, from quantum theory, which demonstrates the interactions between matter and luminous radiation electrons.

Applications of mode-locked ultrashort pulsed lasers

The use of mode-locked ultrashort pulsed lasers is highly promising; the laser system applications include such areas as medical-surgical, microscopy, spectroscopy, telecommunications techniques, and basic science experiments that favor research on fundamental phenomena. Also, the pulsed laser system plays a crucial role in accurate metrology based on optical frequency combs (a type of radiation applied in GPS or remote sensing technologies).

Historical context and master equation theory

These pulsed lasers are not new; they date back to the very birth of the fiber laser systems, although a simple and predictive theory of their behavior appeared later. The laser system theory, called the master equation, was created by Hermann A. Haus and has greatly succeeded in the application of numerous pulsed laser types.

International research and experimental validation

The research group consists of scientists from Spain, France, Italy, New Zealand, and the United Kingdom. They study the theory limitations associated with ultrashort pulsed lasers, which do not explain the laser behavior when the response of the medium is rapid pulse repetition frequency. To solve the problem, scientists have performed a set of semiconductor-based fiber laser experiments that affirm the theoretical predictions of their proposal. The coherent master equation enables them to define the coherent quantum effects observed by other groups in previous experiments under laser systems.

The scientists claim that the novel theory of ultrashort pulsed lasers enlarges opportunities to employ the rich phenomenology of these effects in the design of new types of ML fiber laser systems, which can result in new functionalities and applications, particularly in areas such as accurate metrology or optical communications.

Principle of ultrafast laser systems

A ytterbium laser with thirtyfold compression by a gas-filled hollow-core fiber emits three-optical-cycle (10 fs) laser beam pulses, adding up to 318 W average power. The operating principle of such ultrafast laser systems is based on laser beam pulses of just a few optical cycles in length that interact with matter in unique ways. For instance, in the case of pushing beyond the research lab, such laser systems offer a crucial advantage to the industry.

Development of high-power few-cycle lasers

A group of scientists from Germany has developed an ultrafast laser that produces multimillijoule three-cycle laser beam pulses at a 318 W average power level. This advancement is significant and encourages progress in few-cycle laser technology, leading to new industrial applications, including the HR2 laser system. An innovative method has been employed; 300-fs-long laser beam pulses are directly compressed from a new, record-setting high-energy, high-power laser system to a few-cycle length.

30X compression and hollow-fiber technology

A 30X compression is required, and it has only recently become possible by “the introduction of stretched flexible gas-filled hollow-fiber technology, offering almost unrestricted-length scalability.” A multichannel ytterbium laser is considered to be the largest of its kind that enabling it to emit up to 10 mJ laser beam pulses at up to 1 kW average power and a 1.03 μm center wavelength applied as the light source.

Laser pulse compression using hollow optical fibers

Additionally, scientists employ a 6-m-long stretched flexible hollow optical fiber for the laser beam pulse compression. There is a self-phase modulation between the intense light and the gas atoms, which makes the spectrum broader since the pulses from the ultrafast laser system spread through the argon gas filling the hollow waveguide. It is possible to compress the laser beam pulses with a substantially broadened spectrum to a shorter duration due to the opportunity to reduce their spectral phase with a set of chirped mirrors.

Results and industrial applications

The ytterbium laser system has already been tested and demonstrated great results of producing multimillijoule 10 fs laser beam pulses at a 100 kHz repetition rate and an average power of 318 W, which is regarded as the highest average power ever achieved for a few-cycle fiber laser. This fiber laser technology promotes bringing high-power industry-grade laser systems into the few-cycle regime, enlarging new opportunities for industrial applications, for example, like highly parallelized materials processing. Also, the scientists confirm that this laser system favors completing the transformation of few-cycle technology from research devices to industrial tools.

Human lifestyle requires saving time and money, which is why it is highly necessary to make improvements in technologies, and laser technology is not an exception, because it includes numerous fields of application. This is the reason why a group of researchers from NASA has decided to experiment with a femtosecond laser module.

Femtosecond fiber lasers: features and benefits

Femtosecond laser systems are ultrafast fiber lasers that operate at wavelengths from 1.0 μm and 1.5 μm. Femtosecond fiber lasers, like other types of fiber lasers, offer a lower cost of ownership, eco-friendly technology, and high beam quality. These qualities make femtosecond fiber lasers highly desirable for multiple fields of application. The 
NASA team considers that this ultrafast fiber laser, which can emit pulses of light 100 millionths of a nanosecond in duration, could significantly advance the way NASA manufactures and finally allow assembling the device components made of different materials.

NASA experiments with femtosecond lasers

The experiment demonstrates that the femtosecond laser system has managed to weld glass to copper and glass to glass, as well as drill hair-sized pinholes in different materials. The research group plans to test the fiber laser’s abilities with more exotic types of glass, such as sapphire and Zerodur, and metals such as titanium, Invar, Kovar, and aluminum that are ideally fit for spaceflight tools.
The main aim of the femtosecond laser test is to find out whether the laser module can weld larger pieces of these materials or not. The researchers consider that very soon the laser technology will demonstrate its efficiency at adhering windows onto laser housings and optics to metal mounts, among other applications.

Future applications in photonics

They believe that there are a lot of new ways of laser technology’s applications in fabricating and packaging photonic integrated circuits, for uses ranging from communications and data centers to optical sensors.

Femtosecond laser systems have a lot of benefits that include:

• The waveguide medium eliminates the need for precise alignment and makes a long cavity length possible;
• Fiber lasers offer high beam quality, which is extremely valuable for many areas of fiber laser applications;
• Fiber gain media are efficient and can provide adequate levels of power for bioimaging;
• Fiber lasers are naturally suitable for integration with endoscopic instruments.

The NASA team is sure that they will be able to adapt this emerging technology to a wide variety of flight applications.

Recently, a research team from the USA has advanced laser system technology ten years into the future. The fact is that the research team unified lasers and silicon and developed a mode-locked quantum dot laser module on silicon. It is planned that the laser system will offer new fields of application.

Advantages of the mode-locked quantum dot laser module

The mode-locked quantum dot laser module on silicon has numerous advantages that include:

• a significant increase in data transmission capacity of centers, telecommunications companies, and network hardware products;
• high stability;
• low noise;
• energy efficiency;
• compact size;
• low-cost;
• a tiny, micron-sized light source;
• the ability to emit a broad range of light wavelengths.

Nowadays, the level of data traffic continues growing worldwide, which is why even the largest technology companies have to set their sights on the hardware and laser modules of 2024 and beyond to stay competitive. The developed mode-locked quantum dot laser system is their only solution to the problem.

Key performance of the novel laser system

The novel mode-locked fiber laser has an output of 20 gigahertz, a proven 4.1 terabit-per-second transmission capacity that is higher than today’s best commercial standard for data transmission.

Wavelength-division-multiplexing technology

The researchers used the technique of wavelength-division-multiplexing or WDM, which allows transmitting numerous parallel signals over a single optical fiber using different wavelengths. The laser system technology makes streaming and rapid data transmission real and can be used in different fields of application, such as commerce, communications, entertainment, and more. The mode-locked quantum dot laser module on silicon is a low-phase-noise laser due to coherent optical combs with fixed-channel spacing.

Prospects of silicon-based laser systems

The laser system on silicon is considered to be the most advantageous because it has all the benefits of the electronic properties of several semiconductor materials for performance and function, in addition to silicon’s own well-known optical and manufacturing benefits. The research team confirms that the laser device will soon become the norm in telecommunications and data processing.

Laser technology in the metal cutting industry

The laser system is a universal technology that is ideally suited for numerous areas of application. The metal cutting industry is the number one user of laser technologies for material cutting with lasers. Today, these industries utilize approximately 100 different types of metals worldwide, and virtually all types of lasers can work with them.
Laser technology allows cutting metal easily and effectively. Moreover, new lasers meet growing demand from customers, enabling the reduction of costs and providing quality and safety of the highest level. Recently, a direct diode laser or DDL was developed, and its discovery has greatly changed the method of cutting.

Principle of direct diode laser operation

The direct diode laser system demonstrates impressive results in the metal laser cutter industry. The operation principle of the direct diode laser is based on the use of diodes directly. The system is being changed to the doped fiber system that could be found in fiber laser technologies. This improvement makes the DDL system more cost-effective.

Key benefits of DDL systems

This laser system has other benefits, such as:

• high level of reliability;
• compact size;
• remarkably premium laser beam quality.

Performance advantages for metal cutting

A high level of laser beam quality is provided by programmed loading and unloading of materials into storage. In addition, for the metal cutting industry, speed plays a crucial role because most of the laser cutting machines are made of more lightweight aluminum, and new diode laser provides it. The DDL system uses diodes directly with the aim of the metal cutting process. The diode laser removes the middle process of other laser cutters. The primary use of the diode laser system is for cutting thin materials because of its low electrical power.
The latest improvements allow increasing the electrical power up to 8000 watts, and consequently, it is possible to cut through heavier and thicker metals. The direct diode laser is considered to be more advantageous than disc, CO2, and fiber laser systems.

The DDL system is able to cut metal 15% faster for almost all applications, and offers a 30% faster-cutting speed over aluminum materials. Now, fiber laser systems remain the most popular and cost-effective way for the metal cutting industry.

Supercontinuum breakthrough in fiber lasers

A manufacturer of fiber laser systems offers a supercontinuum breakthrough. Supercontinuum generation is considered to be based on intense laser beam light of one color that runs within a material, similar to glass, and spreads into a spectrum of colors. This fiber laser technology allows emitting a laser beam at colors required for such specific applications as bioimaging, optical communications, and essential investigations of materials.

Until recent times, two ways to produce a supercontinuum were distinguished. The first way includes the application of a thin optical fiber to concentrate a laser beam to high intensity over lengths of a few meters. The second way supposes the focus of a more powerful laser beam from an amplified laser system on the standard glass.

Limitations of conventional techniques

All these techniques have several disadvantages, for instance, large size, complexity, and high cost of applying a high-quality laser beam or the accurate and fragile tuning required to emit fiber laser light into an optical fiber that is only two thousandths of a millimeter in diameter. A team of researchers from Scotland presented a new fiber laser technology for reaching supercontinuum generation.

Novel approach to multicolored fiber lasers

Employing the novel technique, the researchers succeeded in producing a wide range of colors from a single laser system. The new fiber laser technology is based on the combination of a conventional laser system with a special, nonlinear crystal, leading to the design of a supercontinuum directly. Additionally, there is no need for either a high-power fiber laser or delicate coupling of laser beam light into thin optical fibers.

Operating principle with gallium phosphide crystal

The team claims that the operating principle is totally new: “our specially engineered gallium phosphide crystal creates a cascade effect.” The crystal is illuminated with a laser beam from an infrared laser system, and some of these beams are changed to visible green light. This, in its turn, produces more green laser beam light at a slightly longer wavelength, becoming first yellow, then orange, and working all the way out to the red.

Expanding the laser spectrum

It is possible to generate green laser beam light at longer and longer wavelengths from the weaker edges. The researchers plan to expand the spectrum of the fiber laser light and to make it more intense by optimizing the features of the crystal. Further improvements are required to detect whether the effect is specific to the special gallium phosphide crystal that is applied.