Category: Applications of Fiber Lasers

Overview of Ytterbium-Doped Fiber Laser Capabilities

Ytterbium-doped fiber lasers work in a near-infrared spectral window and are capable of high-power operation. They have gained popularity in the recent years due to their high-energy wideband operation. A wide range of physical attributes, like single longitudinal mode, also knows as single frequency, broad gain bandwidth, high power efficiency, outstanding thermo-optical properties and fully alignment-free design, makes them attractive for numerous applications, for example,  light bullet generation, optical frequency comb formation, materials fabrication, free-space laser communication, and biomedical diagnostics.

Current Progress and Limitations in Ytterbium Fiber Lasers

The high demand for ytterbium-doped fiber lasers has forced the fiber laser manufacturers to develop high-power ytterbium fiber lasers that are capable of producing femtosecond pulses. The continuous wave, femtosecond, picosecond operations of the ytterbium-doped fiber lasers have been intensively demonstrated.

Spectral Gaps and the Need for Hyperspectral Capability

Despite the recent developments in scientific fiber laser systems, ytterbium-doped fiber lasers are still limited in the spectral bands:  970-980 nm and 1030-1100 nm. The development of ytterbium fiber lasers that bridge this wavelength gap is important to achieve hyperspectral capability which is important for certain applications, some of which include multicolor two-photon excited fluorescence (TPEF) microscopy, hyperspectral coherent Raman scattering microscopy, etc. Fiber lasers doped with ytterbium will be able to interact with widely used biomolecules and dyes, reducing the illumination power required to work with the dyes.
Femtosecond ytterbium-doped fiber lasers are the most promising as they compare with visible light and can penetrate deeper into biological tissue without inflicting damage. The properties of femtosecond pulse fiber lasers are highly desirable for the following applications: advanced 3D micro-/ nano-structure processing, biological imaging, optical frequency comb formation.

Deep Metal Etching in Industrial Applications

Deep etching in metal is vital for numerous applications, some of which include oil and gas exploration, gun and firearms manufacturing, aerospace, pipelines, and infrastructure projects where metal is used. In most of these applications, the etched metal parts are marked to an epth exceeding 0.254 mm. This depth is justified by the need for the serial number, date of manufacture, and part number to be hard to remove without the metal part breaking. The printed information needs to survive time, elements like water, heat, and cold, oil and gas leaks, collapse of a bridge.

Fiber Lasers as the Leading Technology for Deep Etching

Fiber lasers are considered to be the fastest, easiest, least expensive, and most beneficial way of deep metal engraving for most industrial applications. The deep metal etching is achieved with high-power fiber lasers that are able to cut deeper into the metal at faster speeds. The latest developments of fiber optic technology allow fiber lasers to be controlled during operation, which provides opportunities for wobble features.

Key Advantages of Fiber Laser Deep Etching

There are numerous advantages of fiber laser deep metal etching:

• The use of fiber lasers for metal etching reduces metal fatigue;
• The requirements regarding depth and permanence of metal parts identification are easily complied;
• The costs of deep metal etching are reduced;
• Fiber laser deep metal etching is eco-friendly.

For the past several decades, CO2 lasers and YAG lasers have been used in laser cutting, etching, and engraving applications. However, these lasers are being actively replaced by fiber laser systems as they perform much better at a lower cost. Their rising popularity is explained by their better working parameters, high energy efficiency, fault tolerance, and durability. Fiber lasers are currently used in many laser welding, cutting, and engraving applications and will soon replace all CO2 laser systems.

Femtosecond Laser Micromachining

Femtosecond lasers are being considered for a growing list of micromachining applications with their ability to process any material with a minimal amount of heat-affected zones (HAZ). This type of ultrafast laser is an ideal technology not only for micromachining but also for medical device fabrication, scientific research, eye surgery, and bioimaging. Short pulse durations, along with higher energies and lower costs, are helping femtosecond lasers produce the next generation of medical implants, make smartphone glass covers more durable, and improve the fuel efficiency of automobiles through the drilling of gasoline injector nozzles. The short pulse duration of femtosecond lasers enables material processing with cold ablation. Plus, the optional second harmonic allows smaller features or higher ablation rates.

Advantages of Femtosecond Lasers

Currently, femtosecond lasers and laser systems have become popular tools for machining transparent, brittle materials, as the ability of cold ablation promises process results with the minimum amount of chipping and micro-cracks. The application of femtosecond lasers can result in high cut quality. The very high cutting quality also leads to extremely high bending strength.

High Precision and Nonlinear Absorption

The high peak intensity of femtosecond lasers enables nonlinear absorption inside transparent materials. The availability of femtosecond lasers with more than 100 μJ pulse energy and special multi-foci optics now enables simultaneous modification of four layers, resulting in four-times-faster cutting speeds.

Applications in the Automotive Industry

High precision and excellent process quality are ideal for drilling gasoline injector nozzles. Automakers around the world are under pressure to meet increasingly stronger mileage requirements, so they are working on at least two fronts:

• to design drivetrain systems that run on renewable or alternative fuels
• to wring more mileage out of existing fossil-fuel engine designs

Importance of Nozzle Quality

The spray pattern depends on the injection pressure, but also on the geometry and sidewall quality of the nozzle holes, so these holes must have very smooth walls post-drilling. Historically, these tiny and high aspect ratio holes with 150- to 250-μm diameters have been drilled by electron discharge machining (EDM). However, femtosecond lasers have now reached levels of reliability and pricing so that they can be dependably used in automotive production.

Laser Parameters for Drilling

The process of drilling small, high aspect ratio holes with excellent surface quality requires ultrafast lasers with high energy pulses of 80 μJ or more at ultrashort pulse durations. For the drilling of very narrow holes, higher pulse energies at lower repetition rates are more beneficial than higher output powers and higher repetition rates. For drilling holes with an aspect ratio, a shorter wavelength, such as a second harmonic of a ytterbium laser at around 520 nm, is beneficial. The advantages are a smaller focus spot size and a larger Rayleigh length.

Next Steps in Automotive Applications

The implementation of the laser drilling process for diesel nozzles is the next development step. Ultrafast lasers with pulse energies >40 μJ at wavelengths in the visible range will be necessary to substitute for conventional EDM methods.
Femtosecond lasers will continue to improve in cost-performance as lasers become even more competitive with mechanical machining methods. These lasers will provide higher average powers and pulse energies for higher throughput in the coming years.

Composition and Key Applications of Fiber Lasers

Fiber lasers have an active medium made up of an optical fiber, which is doped with special rare-earth components like ytterbium, erbium, dysprosium, etc. A huge bandwidth and effectiveness of these components allow for cheaper and more compact fiber laser components. This, in turn, allows the production of moderately cheap fiber lasers. Fiber lasers have a variety of applications, such as nonlinear imaging, microscopy, tissue ablation, micro and nanosurgery, and more.

Advantages and Technological Progress

Fiber lasers offer multiple advantages that are often crucial for certain applications and determine the popularity of fiber lasers. Fiber lasers offer an extraordinary surface-to-volume ratio. Fiber optic technology has been rapidly developing for the past 30 years, resulting in significant progress in the field of fiber lasers. Lasers based on the fiber optic technology have been renovated into multimodal and single varieties with ultraviolet to far-infrared wavelengths that display high-power levels, adjustable repetition rate, and short pulse duration that is present in femtosecond fiber lasers.

Femtosecond Fiber Lasers and Industry Benefits

Generally, femtosecond fiber lasers operate at wavelengths from 1.0 μm and 1.5 μm. Femtosecond fiber lasers, like other types of fiber lasers, offer 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 growing trend of green engineering through multiple industries has made these lasers a smart choice for marking and cutting applications. Fiber lasers are easy to automate and are energy proficient, which makes them a better substitute for traditional means of marking, such as ink-based printing and chemical etching.

Advances in Optical Microscopy and Fiber Laser Technology

Sub-micron spatial imaging resolution can be achieved through the use of optical microscopy, which offers well-established techniques. The development of fiber optic technology, including fiber laser systems, has been noticed and used in many applications. Recently, researchers have found that ultrashort light pulses that are produced by femtosecond fiber lasers can be utilized in a variety of new biomedical imaging modalities. There are several techniques that utilize the high peak power that is possible with ultrashort pulses. The pulses can be focused to high intensity to drive nonlinear-optical processes, for example, multiphoton absorption in molecules used as fluorescent labels.

Chemical Contrast Imaging with Vibrational Spectroscopy

Biologically important substances, like lipids, nucleic acids, sugars, etc., have characteristic vibrational spectra which can be distinguished easily. The generation of images with chemical contrast is possible through the use of microscopy with vibrational spectroscopy. The imaging is a basis of coherent Raman scattering (CRS) microscopies – it allows for the detection of the presence of certain substances without the use of exogenous dyes.
The development of femtosecond fiber lasers has been a big step in achieving new advances in nonlinear microscopy. Femtosecond fiber lasers have enabled dramatic growth of multiphoton and harmonic-generation imaging.

Key Benefits in Bioimaging Applications

This can be explained by various benefits that fiber lasers offer:

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

Recently developed femtosecond fiber lasers outperform traditionally used solid-state lasers. Femtosecond fiber lasers are already used as an alternative to solid-state lasers in many different applications, and the research that is being put into the further development of femtosecond lasers means that they will continue to replace solid-state lasers.

Fiber Laser Applications in Material Processing

Multimode fiber lasers have been used in concrete drilling and cutting. The reason behind the use of a fiber laser system in this application is the ability of fiber lasers to cut concrete without fracturing it. The concrete structures that are designed to be earthquake-proof often contain things like rebar to bolster their strength so they won’t just crumble if an earthquake hits. Conventional drilling techniques are not gentle enough for concrete structures. This is where fiber laser cutting systems are used.
Fiber laser systems are already used in other cutting and drilling applications; for example, Q-switched fiber lasers are used in pulsed materials working, such as laser marking or working semiconductor electronics, as well as for LIDAR.

Ultrafast Fiber Lasers for Micro- and Nanoscale Machining

There is a significant interest in smaller fiber lasers for micro-and nanoscale machining. For fiber lasers that have a short enough pulse duration, shorter than about 35 ps, no material splatter occurs during cutting or drilling, just ablation, eliminating the formation of kerfs and other unwanted artifacts on the metal being cut. Femtosecond fiber lasers are able to cut materials without heating the surrounding area, allowing material work without damaging or weakening the surrounding area. Moreover, holes can be cut with high aspect ratios, e.g., drilling rapidly drilling small holes through 1-mm-thick stainless.

Medical and Transparent Material Applications

Femtosecond fiber lasers are extremely useful in a variety of applications that deal with transparent materials. They are widely used in LASIK eye surgery, where femtosecond fiber lasers are used to cut flaps by being focused tightly with a high-numerical-aperture lens onto a spot below the eye’s surface, causing no damage at the surface, but a breakdown of the eye material at a controlled depth. Due to this, the cornea – an area of the eye that is crucial for vision – remains unharmed. Femtosecond fiber lasers, along with picosecond fiber lasers, are used in a variety of other medical applications, some of which include shallow-penetration surgery in dermatology and use in certain kinds of optical coherence tomography (OCT).

Scientific Applications of Ultrafast Fiber Lasers

There are many other areas of femtosecond fiber laser and picosecond fiber laser applications besides drilling and cutting. Scientific applications of femtosecond fiber lasers include laser-induced breakdown spectroscopy, time-resolved fluorescence spectroscopy, and general materials research.

Growth and Advantages of Fiber Laser Systems

The use of fiber laser systems in production continues to grow because, in terms of price per watt, beam quality, and energy efficiency, they consistently deliver the highest performance at the lowest operating cost. The applications of fiber laser systems are constantly expanding – from traditional cutting and welding to more advanced 3D printing and surface texturing.

Laser technology is widely used in cutting, drilling, welding, and more. Fiber lasers provide high power and accuracy to these applications while maintaining low maintenance costs. Most fiber laser manufacturers offer a wide range of products that are designed according to the needs of a specific area of fiber laser applications. The ability to manufacture custom fiber laser systems is crucial for certain applications that require precise laser power, wavelength, and other specifications.

Fiber Lasers vs CO2 Lasers

Fiber laser systems are superior to traditionally used CO2 lasers, which were widely used for laser cutting applications. Traditional CO2 lasers have numerous drawbacks, while fiber lasers for cutting applications provide several advantages.

• High Beam Quality. High beam quality fiber lasers allow cutting, engraving, and marking a wide range of metallic materials.
• Power Output Range. Fiber lasers have a large range of power output, ranging from 500W and up.
• Cutting Capability. Fiber laser systems for cutting applications provide a machine capability for cutting sheet metals.
• Speed and Efficiency. Fiber lasers, specifically femtosecond fiber lasers and picosecond fiber lasers,  provide faster processing times and reduced energy consumption due to increased efficiency.
• Maintenance and Productivity. Fiber laser cutting systems require minimal maintenance. Higher productivity of fiber lasers makes them ideal for laser cutting applications.
• Main Application Areas. Main areas of fiber laser cutting applications include precision engineering, including fiber laser micromachining, high precision sheet metal profiling, cutting transparent materials, marking components for traceability, and more.

Advances in Fiber-Optic Laser Technology

In recent years, important progress has been made in the development of fiber-optic technologies in general and, in particular, in the development related to fiber lasers. Fiber-optic lasers are compact and reliable; they are used more and more in surgical procedures in such areas as diagnostic, therapeutic, and surgical medical activities. Optical fiber lasers have a large number of unique features, like great flexibility, convenience, and reliability in surgical applications. The fiber’s waveguiding properties supply single-mode operation that creates excellent diffraction-limited beam quality. This is especially useful in microsurgery and nanosurgery because it provides high resolution of the focusing spot.

Integration with Surgical Devices

Fiber-optic lasers allow the light to be easily integrated into endoscopes, microscopes, and other surgical devices. Also, many fiber lasers have a wall-plug efficiency of around 30 percent, while some thulium fiber lasers have a wall-plug efficiency of around 12 percent. Combine this with the supple nature of fiber, which can be bent and coiled into a space about the size of a shoebox, and fiber lasers become portable, which is critical for emergency surgery.

Fiber Laser Composition and Advantages

Fiber-optic lasers typically comprise a single-mode fiber core doped with erbium, ytterbium (or their combination), or thulium. The optical fiber itself in fiber-optic lasers is the resonator cavity. Energy is coupled into the fiber’s cladding from a solid-state source, then moves into the core and pumps the dopant. These optical fiber lasers have significant advantages over other types of lasers, like higher efficiency, wider tunability, and better beam quality, which, as a result, contribute to the fact that these lasers widen the utility of lasers in general for medical applications.

Medical Applications of Fiber Lasers

The targeted nature of the laser beam is attractive to many surgeons who work in a variety of fields. Fiber sources can access hard-to-reach areas of the body and deliver targeted cutting, ablating, or cauterizing while minimizing damage to the surrounding tissues.

Ophthalmology and Vision Correction

At the moment, the market of medical equipment is filling up with fiber-optic lasers, which have an all-femto single-step system. These lasers allow for the correction of vision without having to create a flap in the cornea, to perform corneal transplant procedures, and intracorneal ring implantation.

Dental and Aesthetic Applications

With different groundbreaking developments in the sphere of fiber-optic lasers, the scientists have been successful in gaining long-range applications of fiber lasers in the medical sector. Optical fiber lasers are actively used in dental implementation and ophthalmology to achieve aesthetic properties such as skin rejuvenation, body contouring, and hair removal.

History of Lasers in Dentistry

The first laser was developed in 1960, and many other lasers and laser systems were created rapidly thereafter. Dental researchers began investigating lasers’ potential. For example, Stern and Sognnaes reported in 1965 that a ruby laser could vaporize enamel. In 1989, the first laser specifically designed for dental use became available. There are dozens of indications for use with various dental laser devices, and the clinical applications continue to increase. In the last two decades, there has been an explosion of research studies in laser applications.

Hard tissue applications

In hard tissue application, the laser is used for caries prevention, bleaching, restorative removal and curing, cavity preparation, dentinal hypersensitivity, growth modulation, and for diagnostic purposes.

Soft tissue applications

Soft tissue application includes wound healing, removal of hyperplastic tissue to the uncovering of impacted or partially erupted teeth, photodynamic therapy for malignancies, and photostimulation of herpetic lesions.

Types of Dental Lasers

Lasers are generically named for the material contained within the center of the device, called an optical cavity. One common for dentistry type of fiber laser is a fiber laser with carbon dioxide as a gaseous active medium. The other devices are either solid rods of garnet crystal combined with other elements, or solid-state semiconductor fiber lasers are called diodes, and the crystal fiber lasers are designed with acronyms such as Nd:YAG, and the like.

Each wavelength has a somewhat unique effect on dental structures, due to the specific absorption of that laser energy in the tissue. Lasers in dentistry can be categorized into three groups.

Diode and Nd:YAG lasers

Diode and Nd:YAG laser wavelengths target the pigments in soft tissue and pathogens, as well as inflammatory and vascularized tissue.

Carbon dioxide lasers

Carbon dioxide lasers interact with water molecules in soft tissue and vaporize the intracellular water of pathogens.

Erbium lasers

Erbium lasers (Er, Cr:YSGG and Er:YAG) interact with the water of soft and hard tissue. Erbium-doped lasers have excellent thermal relaxation, and very little collateral thermal damage occurs in tissues when proper parameters are followed. Erbium lasers can be used anywhere a scalpel is employed, including periodontal procedures, gingival contouring, biopsies, frenectomies, pre-prosthetic procedures, and the like.

There are two basic emission modes for dental lasers: continuous wave and pulsed. Continuous wave lasers emit energy constantly for as long as the fiber laser is activated: carbon dioxide and diode lasers operate in this manner. Nd:YAG, Er:YAG, and Er:YSGG devices operate as free-running pulsed lasers.