At present, the types of pulsed fiber lasers used on laser marking mainly includes: Q-modulation technology and MOPA technology.
MOPA (Master Oscillator Power-Amplifier) laser refers to a laser structure that consists of a laser oscillator cascaded with an amplifier. In industry, MOPA laser refers to a unique, more “intelligent” nanosecond pulsed fiber laser consisting of a semiconductor laser seed source driven by an electrical pulse and a fiber amplifier. Its “intelligence” is mainly reflected in the output pulse width is independently adjustable (the range can be up to 2ns-500ns), and the repetition frequency can be up to MHZ.
Q-modulated fiber laser seed source structure is to insert the loss modulator in the fiber oscillation cavity, by periodically modulating the optical loss in the resonant cavity to produce a certain pulse width of nanosecond pulse light output.
The difference between Q-modulation and MOPA technology in fiber lasers
Here is a brief analysis from three aspects: laser internal structure, output optical parameters and application scenarios.
Laser internal structure
The difference between the internal structure of MOPA fiber laser and Q-modulated fiber laser is mainly in the way of pulse seed light signal generation.
The MOPA fiber laser pulsed seed light signal is generated by the electric pulse driving the semiconductor laser chip, i.e., the output light signal is modulated by the driving electric signal, so there is great flexibility for generating different pulse parameters (pulse width, repeated frequency, pulse waveform and power, etc.).
Q-modulated fiber laser pulse seed light signal is to generate pulsed light output by periodically increasing or reducing the optical loss in the resonant cavity, simple structure, more price advantage. However, the pulse parameters are limited by the influence of Q modulation devices, etc.
Output optical parameters
The output pulse width of MOPA fiber laser is independently adjustable. MOPA fiber lasers have an arbitrary tunable pulse width (ranging from 2ns to 500ns). The narrower the pulse width, the smaller the heat affected area, and the higher the processing accuracy.
Q-modulated fiber laser output pulse width is not adjustable, pulse width generally output in 80 ns ~ 140 ns a fixed value of the same.
MOPA fiber lasers have a wider range of repeated frequency, reaching high frequency output of MHz. High repeated frequency means high processing efficiency, and MOPA can still maintain high peak power characteristics under high repeated frequency conditions.
Q-modulated fiber laser is limited by the operating conditions of the Q-switch and have a narrow output frequency range, reaching only ~100 kHz at high frequency.
MOPA fiber laser has a wide range of parameters, so in addition to covering conventional nanosecond laser processing applications, it can also take advantage of its unique narrow pulse width, high re-frequency, and high peak power to achieve some unique precision processing applications. For example:
Aluminum oxide thin sheet surface stripping
Nowadays, electronic products are getting thinner and thinner, and many cell phones, tablets, and computers use thin aluminum oxide as the shell of the product.
When using a Q-modulated laser to mark conductive bit on the thin aluminum plate, it is easy to lead to material deformation, the back of the projection, directly affecting the appearance of the aesthetic.
The MOPA laser with smaller pulse width parameters can make the material difficult to deform, the bottom pattern is also more delicate and bright white. This is because the MOPA laser uses a small pulse width parameter that allows the laser to stay on the material for a shorter period of time and has high enough energy to remove the anode layer. So the MOPA laser is a better choice for thin aluminum oxide plate surface stripping anode processing.
Anodized aluminum oxide marking blackening
Using laser to mark black logo, model number, text, etc. on the surface of anodized aluminum material, this application has been gradually used by Apple, Huawei, ZTE, Lenovo, Meizu and other electronic manufacturers in the last two years to mark black logo, model number, etc. widely on the shell of electronic products. For this kind of application, only MOPA laser marking machine can process it at present.
As the MOPA laser has a wide range of pulse width and pulse frequency adjustment, the equipment with narrow pulse width, high frequency parameters can be used to mark black effect on the surface of the material. Through different combinations of parameters, it can also mark different grayscale effect.
Color laser marking
Color laser marking is a new type of laser marking process. At present, only MOPA fiber laser marking machine temporarily mark with color patterns on metal materials such as stainless steel, chromium, and titanium.
When color laser engraving on stainless steel materials, the laser beam can be adjusted to change the color change of the surface layer of the material, so as to obtain the decorative effect of different colors. For the stainless steel products industry, you can add the color of the marking pattern, you can edit a variety of text patterns as you like, convenient and easy to operate, environmentally friendly and pollution-free, fast marking speed, which can significantly enhance the added value of stainless steel products and market competitiveness.
Electronic, semiconductor, ITO precision processing
In the precision processing of electronics, semiconductors and ITO, many times fine scribing application are needed.
Q-modulated lasers cannot adjust the pulse width parameter due to its own architecture, so it is difficult to achieve fine scribing lines.
MOPA laser can flexibly adjust the pulse width and frequency parameters, which not only makes the scribed lines fine, but also makes the edges appear smooth and not rough.
In general, the MOPA fiber laser pulse width and frequency is independently adjustable with a wide range, so the processing is fine, low thermal effect. In aluminum oxide thin plate marking, anodized aluminum marking black, stainless steel color mark, etc., the advantages are outstanding, MOPA fiber laser can achieve better effect.
The Q-modulated fiber laser is characterized by stronger marking, and has certain advantages in the deep engraving for metals, but the marking effect is rougher.
In the common marking applications, users can choose the right laser according to the actual needs of the marking material and effect.
MOPA laser marking machine performance characteristics
MOPA laser marking machine (laser marking machine for aluminum marking black, color laser engraving machine) belongs to the category of laser marking machine. Compared with the Q-modulated fiber laser, MOPA fiber laser pulse frequency and pulse width are independently controllable, through the two laser parameters to adjust with, by the high speed scanning oscillator system, allows for constant high peak power output and a wider range of substrates to be marked.
MOPA laser marking machine has high quality laser beam, low cost of use, 100,000 hours maintenance-free, suitable for aluminum oxide black, 304 stainless steel color, stripping anode and coating, semiconductor and electronics industry, plastic and other sensitive materials marking. The environmental protection of marking pattern/font meets ROHS standard.
Compared with the general laser marking machine, MOPA laser marking machine M1 pulse width is 4-200ns, M6 pulse width is 2-200ns. Ordinary laser marking machine pulse width is 118-126ns.
It can be seen that the MOPA laser marking machine pulse width can be adjusted in a wider range, so you can understand why some ordinary fiber laser marking machine can not reach the marking effect, but MOPA laser marking machine can do.
However, many customers purchase a MOPA laser marker to expect the same processing speed as a regular fiber laser marker, but this is clearly not the case.
The two technologies are different.
When engraving color effects, the machine needs to mark at high frequencies with minimal shadow effects, which allows for high resolution engraving, but at the same time engraving is relatively much slower. In addition, in the deep marking for metal, MOPA laser marking machine may not have the advantage, because there is no advantage on the single pulse energy, but the effect in terms of fine is better than the general laser marking machine.
Therefore, before customers choose to buy MOPA laser marking machine, they need to understand the advantages and disadvantages of this type of laser marker.
MOPA laser marking machine is suitable for fine marking process of metal and non-metal materials, such as digital product parts, cell phone back cover, IPAD, aluminum, cell phone keys, plastic translucent keys, electronic components, integrated circuits (IC), electrical appliances, communication products, sanitary ware, tool accessories, cutting tools, glasses and clocks, jewelry, auto parts, luggage ornamental buckle, cookware, stainless steel products and many other industries.