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Narrow linewidth lasers, or lasers that have a small optical linewidth, are usually single-frequency, with low RIN and high spectral purity as a result of low phase noise.
The most common types of narrow linewidth lasers are distributed feedback laser diodes and distributed Bragg reflector lasers. Ultra narrow linewidths can be achieved by using a single-mode fiber that contains a narrow-bandwidth fiber Bragg grating in a resonator. Special fiber Bragg grating used in distributed feedback lasers also allows for a narrow linewidth of a few kilohertz. Narrow linewidth lasers with high output powers can be achieved in the form of longer distributed Bragg reflector lasers. Other lasers that have a narrow optical spectrum include diode-pumped solid-state bulk lasers and external-cavity diode lasers.
Several difficulties emerge in the manufacturing of narrow linewidth lasers and ultra narrow linewidth lasers. First of all, achieving single-frequency operation is crucial to get narrow linewidth; the goal is a stable single-frequency operation without mode hopping over a relatively long period of time.
Secondly, minimizing noise influences from external sources is problematic. There are multiple ways of resolving a problem of external noise influences. A stable resonator setup with a protection against vibration may be used. Certain lasers require specific solutions; for example, a low-noise current source should be implemented into the operation of electrically pumped lasers; optically pumped laser should have a low-intensity noise pump source. A Faraday isolator is often used to avoid optical feedback.
Thirdly, the laser itself, its design in particular, should be manufactured with a goal of minimizing laser and phase noise. Long resonator and a high intracavity optical power can be beneficial to construct a narrow linewidth laser.
Narrow linewidth lasers have a variety of applications: strain and temperature fiber-optic sensors, gas detection, LIDAR, wind speed measurements. Ultra-narrow linewidth lasers are used in optical frequency metrology.
If you would like to buy Optromix narrow linewidth single frequency laser, please contact us at info@optromix.com or +1 617 558 98 58.

CW fiber lasers operate continuously, they constantly emit light, as opposed to lasers that operate with pulsed pumping. Fiber lasers are often the only ones to operate continuously, as fiber greatly increases gain efficiency. CW lasers typically function with an output of power that is constant, however, some power variations may occur due to mode beating; this is mostly true for non-single frequency lasers.
The continuous nature of a laser beam may be achieved through ionizing gas (like in CO2 lasers) just below a critical level to be in a plasma state; the output of such laser can be turned on and off by controlling the amount of power at the threshold. If the input of power is just above the threshold, the plasma will produce a laser beam. This is one of the principles behind CW fiber laser technology.
CW fiber lasers differ by their power levels:

• high power CW lasers;
• medium power CW lasers;
• low power CW lasers.

High power lasers, including high-power CW fiber lasers, are the most popular variety of all lasers. High power output is required for many different applications, some of them include large laser displays, LIDAR, particle acceleration, material processing and more. Despite a wide scale use of these lasers, it is not determined what exactly is a high power laser. Typically, an output of a few hundred watts will classify a laser as “high powered”. In some areas, however, an output of a few dozens of watts is considered high.
High power CW fiber lasers are inherently brighter than other laser systems due to the high power output. Another important benefit of these lasers is their versatility. Beam switchers, couples and sharers are readily available for high-powered fiber lasers and can be used for customization.
High power CW fiber lasers are most frequently used in optical sensing, optical tweezing, atomic trapping and cooling, spectroscopy, efficient second-harmonic generation and more.
The design of high-power fiber lasers often involves challenges. Their prime limitation is a thermal degradation of fiber coatings. The thermal effects make it more difficult to achieve high efficiency at high power output.
Other effects that become relevant during the use of high-powered fiber lasers include: 1) Raman scattering; 2) four-wave mixing; 3) Brillouin scattering; 4) conversion of pump power into heat that may potentially lead to laser crystal fracture.

Optromix offers a number of high-power CW fiber lasers suited for different applications. If you would like to buy CW high-powered fiber lasers, please contact us at info@optromix.com or +1 617 558 98 58.

Optical tweezers, also known as optical traps, were first introduced in 1986 and since then have been widely used in different applications, being particularly successful in the field of biological studies, where optical tweezers are used to study DNA sequences, interactions of proteins, etc.
Optical tweezers have been used in numerous studies which involve optical tweezers in order to trap single atoms, viruses, single-cell organisms, strands of DNA, bacteria, carbon nanostructures and many others. The manipulation and assembly of structures on a nanoscale are the most promising advances right now.
The main principle of optical tweezing lies in the fact that light carries momentum that is in proportion to its energy, and the direction of light is the same as the direction of propagation. After interacting with an object, light beam changes its momentum; same happens with an object after interaction with a beam of light – it undergoes a change of momentum by an equal amount. These interactions result in a reaction force, which acts on the object.
In most optical tweezer set ups, light is emitted by a laser beam which is focused on a particular spot. A trap, that is able to hold a small dielectric object, appears in the spot. The scattering force, that occurs when light hits the object and scatters by its surface, produces a momentum transfer that leads to the object being pushed to the beam of light. This method allows to trap an object in all dimensions.
It is critical that lasers used to create an optical trap are highly stable. Ytterbium lasers are often used in optical tweezer systems as they produce a stable and high-power laser beam which allows for interference-free optical trapping. Other properties of Yb lasers include:

• a simple electronic level structure;
• a small quantum defect, which provides an opportunity for high power efficiency;
• Yb lasers have a capacity for wide wavelength tuning;
• a low-noise beam that allows to create an optical trap in a precise spot.

All of these characteristics make Ytterbium lasers one of the most optimal options for light emitters in optical tweezer systems. These lasers have already been used in multiple studies that utilize optical trapping for capturing micron-sized particles and living cells, superior pointing stability being the main reason these lasers are chosen over other types.
Optromix provides Ytterbium lasers that can be used in optical tweezing with great efficiency. If you would like to purchase Ytterbium lasers, please contact us at info@optromix.com or +1 617 558 98 58.

Beam quality can sometimes be an overlooked quality of a laser; however, this characteristic provides several advantages, such as faster and finer-feature machining, better process quality and an increased depth of focus. High beam quality laser has strong focusing capabilities and allows for a longer working distance which means that these types of lasers can be used in rough working environments without damaging the optics and the laser itself.
Beam quality is defined by M2, which represents a ratio of the beam of the laser and the perfect beam; consequently, the closer M2 is to 1, the better the quality of the laser beam. High beam quality lasers have M2 of less than 1,3. Due to the aforementioned reasons, lasers with high beam quality are very precise as they can produce an optical spot down to 20 microns. The best beam quality is produced by single mode lasers with M2 values around 1,1 – 1,2.
High-quality beam lasers prove to be useful in a variety of different applications:

1. Micro machining

The fine-tune nature of high-quality beam lasers is used to conduct machining operations on a small scale – drilling, slotting, cutting, etc. Laser surface engraving, for instance, is a process of emergence of small cracks in a material (around 100μm in size) under the pressure of melting and evaporation that occurs when a laser beam hits a surface.

2. Surface scrubbing

High beam quality provides consistency in scrubbing quality and high tolerance to defocusing during removal of thin materials from other films or a substrate. The low M2 does not result in quality degradation when the laser defocuses. The defocusing of a system occurs due to an uneven working surface, and lasers with high M2 can potentially result in a decreased production yield.

3. Removal of skin pigment and dye

High beam quality lasers are used to remove skin pigmentation and tattoos.
Generally, gas lasers, like CO2 lasers, exhibit a high beam quality. Optromix CO2 lasers demonstrate outstanding results in processing different types of materials with varied thickness. In Optromix, we aim to provide the best experience to our customers, and we will configure your laser system exactly according to your requirements. If you would like to buy high beam quality lasers, please Contacts at info@optromix.com or +1 617 558 98 58.

 

Narrow linewidth fiber lasers with fiber output connectors are widely used as laser sources in high sensitive optical fiber sensing fields, such as submarine hydroacoustic detecting and distributed acoustic sensing.
Currently, the practical optical fiber hydrophone system is based on the optical fiber interferometer technology. A multi-wavelength narrow linewidth laser or a laser array composed of multiple single-wavelength narrow linewidth lasers, where the multiple wavelengths should be in the international telecommunication union (ITU) grid, is needed for the large scaled hydrophone array.
The laser array composed of multiple single-wavelength laser modules is always cumbersome and complicated in the configuration. Consequently, a laser with the multi-wavelength output is attractive for its compact structure and usability. In recent years, the narrow linewidth fiber laser with the compact structure has been realized in distributed feedback (DFB) fiber laser where a short phase shifted fiber grating in erbium-doped fiber as the distributed feedback laser cavity assures the robust single longitudinal mode operation. This distributed feedback fiber laser can be used as a sensing element in the high sensitive acoustic detecting field and has been extensively studied previously. However, since the linewidth of the DFB fiber laser is very sensitive to the ambient noise, the precise temperature control for each cavity, the sound isolation packages for each cavity, and the whole laser configuration are necessary to make it stable and practical.
As for the wavelength number that this configuration can realize, it depends on the pump threshold of each laser cavity, the loss in the array, and the required power uniformity of the laser output. If the wavelength number increases, the power uniformity is more difficult to control. Usually, the pump threshold of the cavity is very low and much smaller than 5 mW, normally ~1mW.
Currently, the eighth-wavelength laser with 120-mW total power and 1.2-dB power difference within the wavelengths is obtained. Scientists expect that more wavelengths should be realized through reducing the loss in the array and adjusting the structural parameters of the laser cavities to meet the requirement in the larger scaled optical fiber sensing. The prototype based on this laser configuration is just in progress in the lab.
Optromix Company priority is to deliver the highest quality laser systems to our clients; we manufacture unique lasers for your specific needs.
If you would like to buy Optromix narrow linewidth fiber lasers, please Contacts at info@optromix.com or +1 617 558 98 58
 

Nowadays, optical scientists have generated ultrashort laser pulses in an optical fiber by using a method previously considered as physically impossible to achieve. Pulses can be generated in fiber lasers by a system known as a saturable absorber. When the light intensity is low, the absorber blocks light; when it is high, it lets it through. Since in femtosecond pulses the light intensity is much greater than in a continuous beam, the parameters of the absorber can be adjusted so that it only lets through such pulses. To generate higher energy femtosecond pulses in the optical fiber, the Warsaw physicists decided to improve saturable absorbers of a different type that relies on nonlinear optical effects causing a change in the refractive index of glass.
A nonlinear artificial saturable absorber works as follows. At the input, linearly polarized light is divided into a beam with a low intensity and a beam with a high intensity. The medium of the absorber can be chosen so that both light beams to experience a slightly different refractive index: that is, for them to travel at slightly different (phase) velocities. As a result of the velocity difference, the plane of polarization starts to rotate. At the output of the absorber, a polarization filter only lets through waves oscillating perpendicularly to the plane of polarization of the incoming light. When the laser is operating in continuous mode, the light in the beam is of a relatively low intensity, an optical path difference does not occur, the polarization does not change, and the output filter blocks the light. At a high enough intensity typical for femtosecond pulses, the rotation of polarization causes the pulse to pass through the polarizer.
The key performance figures of femtosecond lasers are the following:

1. the pulse duration (which is in some cases tunable in a certain range)
2. the pulse repetition rate (which is in most cases fixed, or tunable only within a small range)
3. the average output power and pulse energy

Optromix company offers few types of powerful femtosecond fiber lasers with high-frequency pulses. Amplifier compact size, no need to make adjustments when installing and air-cooling system allow using the femtosecond laser for industrial (OEM) and scientific purposes. Laser characteristics are optimal to perform ophthalmic surgery, spectroscopy, and micromachining. If you would like to buy Femtosecond Fiber Laser Series, please Contacts at info@optromix.com or +1 617 558 98 58

The main laser parameters are:

• Amplitude Noise (RIN). Dominates in direct detection scheme particularly in analog systems Frequency or Phase Noise;
• Frequency Stability;
• Output Power;
• Tuning Range (Frequency).

In frequency modulation (FM) formats phase or frequency, fluctuations compete with the signal. Reducing these fluctuations increases a signal to noise ratio. A laser signal may be used to interrogate path length changes in sensors such as a fiber Bragg grating (FBG) or Mach-Zehnder interferometer (MZI). If the frequency or phase of the laser changes it appears as a change of the path length thus degrading the signal to noise ratio.
There are different types of low phase noise lasers:
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Optromix Company offers CW fiber laser modules for OEM integration: single mode green and single frequency fiber laser modules. The laser module is particularly suited for OEM system integration when a compact design and remote beam delivery are critical factors. The laser part and the optical head can be ordered separately, which offers high flexibility to the customer in designing a laser projection system.
The module includes fully integrated laser control electronics, as well as continuous monitoring of the laser performance.
The single frequency fiber laser module is available in two different laser versions, Erbius-SF and Irybus-SF. Moreover, the laser offers a wide thermal wavelength tuning range and can be combined with fast wavelength modulation e.g. for external stabilization. The single frequency fiber laser modules key parameter is an ultra-narrow linewidth (< 100 kHz) based on the longitudinal single mode. Continue reading

Narrow linewidth lasers with good beam quality attracted much attention in recent years due to their laser diverse applications in remote sensing, gravitational wave detection, nonlinear frequency conversion. Recently, reported a widely tunable in the middle infrared radiation (2.7 to 17 μm). Additionally, 1064 nm has especially application in sum frequency generation (SFG) with 1319 nm to produce 589 nm sodium laser guide star (LGS). Nowadays, there are several kinds of LGS format, such as continuous wave (CW), quasi-CW (QCW) microsecond (μs) pulse, and mode-locked short pulse.
Optromix Erbius-SF-1550-X series is a low-noise single frequency 1550 nm fiber laser based on a longitudinal single mode has a wide range thermal wavelength tuning and optional active wavelength control.
Optromix Company designed Erbius-SF-1550-X as a 19-inch benchtop module for an effortless industrial turn-key integration. Erbius-SF-1550-X comes with a piezoelectric tuning with internal and external wavelength modulation at kHz bandwidth for locking purposes. This is a perfect tool for research labs due to excellent performance, high reliability, and lower cost.
Single Frequency CW laser have unique key features, such as Ultra Narrow linewidth (<1 kHz). The typical linewidth is <1 nm for standard multiline models and is either in the kHz or MHz range for single-frequency options.
CW lasers in the ≤100 W power range are single-mode with theoretically limited beam quality, typical M2 ≤1.05. However, when the application requires it, multimode lasers are also offered.  Due to an absence of thermal lensing in the laser cavity, fiber lasers maintain beam mode quality and divergence over the full range of output power adjustment. This is not the case with DPSS bulk lasers which are typically optimized to run at the nominal power level.
The CW fiber lasers in the ≤100 W power range typically have fixed wavelength. Most models allow the user to select the wavelength over a certain range prior to the purchase of the laser. For Ytterbium lasers, the typical wavelength range is 1030-1090 nm (Yb CW fiber lasers in the range 978-1020 are also available); for Erbium lasers, the range is 1535-1565 nm; for Thulium lasers the range is 1.9-2.05 µm.
There is a great variety of Single frequency fiber laser applications, f.e. atomic trapping and cooling, optical tweezers, spectroscopy, efficient second-harmonic generation, LIDAR and optical sensing. If you would like to buy Optromix single frequency CW 1550 (1535 – 1580 nm) high power fiber laser Erbius-SF-1550-X series, please Contacts at:info@optromix.com or +1 617 558 98 58

Four types of lasers can be used for micro welding: pulsed neodymium-doped yttrium aluminum garnet (Nd: YAG), continuous wave fiber, quasi-continuous wave (QCW) fiber, and nanosecond fiber. Each type offers unique features that work best for specific applications. In some cases, several options may work: that’s when a cost of ownership and service -ability can tip the scales.
With the Nd: YAG laser, the active gain medium is neodymium, which is doped into a host crystal of yttrium aluminum garnet. This solid rod of material is typically 0.1 to 0.2 inch in diameter and about 45 in long. Micro welding Nd: YAG  lasers are optically pumped using flash lamps, they emit light which a wavelength of 1,064 nm, but can be frequency doubled (532 nm) to appear green. With the excellent pulse control, the Nd: YAG laser also offers high peak powers in small laser sizes, which enables welding with large optical spot size. The pulsed Nd: YAG laser is suitable for spot welding applications with less than 0.02-in. penetration and seam welding of heat sensitive packages.
A fiber laser is generated within a flexible doped glass fiber that typically is 10 to 30 feet long and 10 to 50 microns in diameter. Ytterbium is used as the doping element because it provides good conversion efficiency and a near 1-micron output wavelength, which matches well with existing laser delivery components.
The efficient lasing process allows the fiber laser to be small, air-cooled and offer high wall plug efficiencies. The fiber laser unique characteristics are its focusability and it’s beam qualities that can be fine-tuned for each welding application. The two ends of the beam quality spectrum are single mode and multimode. Single mode is defined by a beam quality of M2  less than 1,2, while multimode generally is above M2 of 2.
For high-speed seam welding applications, the fiber laser is operated in CW mode. In other words, the laser output remains on until it is turned off. For spot welding either a single weld or seam, the laser output can be pulsed or modulated, which means the laser is turned on and off rapidly. Cw fiber lasers are suitable for general seam welding up to 0.06 in. deep for a 500-W laser, high-speed seam welding of same and dissimilar materials, and producing spot welds less than 100 microns in diameters.
 
Quasi-continuous wave fiber lasers peak power and pulse width characteristics are similar to those of the Nd: YAG laser through the parameter range is not quite as broad. Similar to CW fiber lasers, the QCW lasers offer single mode to multimode options with spot sizes from 0.001 to 0.04 in. These lasers also shine in small spot size and small penetration applications, although they do offer fairly comprehensive coverage of many micro welding applications.
Nanosecond fiber laser typically used for laser marking applications can be repurposed for certain welding applications. It provides multi-kilowatt peak power, but with the pulse width of 60 to 250 nanoseconds that can be delivered between 20 and 500 kilohertz. This high peak power enables welding of almost any metal, including steel, copper, and aluminum. The very short pulse widths enable very fine control for welding small parts, as well as the ability to weld dissimilar materials.