What is the difference between MOPA laser and fiber


MOPA (Master Oscillator-Power Amplifier) laser generator is a kind of laser generator which is composed of a laser oscillator and an amplifier. In the industrial field, MOPA laser generator refers to a unique and more "intelligent system" nanosecond single-pulse fiber laser generator composed of semiconductor laser seed source and optical fiber sensor driven by pulse current.

The key of its "intelligent system" is that the output pulse width is individually adjustable (the range can reach 2ns-500ns), and the repetition frequency can reach megahertz. The seed source structure of the Q-switched fiber laser generator is to insert a loss demodulator in the oscillating cavity of the fiber line, and generate a nanosecond pulse laser output with a certain duty ratio according to the periodic allocation of the optical loss in the resonator.

The nanosecond single-pulse laser generator has been familiar with industrial production applications such as metal material marking, electric welding, cleaning, laser cutting, etc. As the two completion methods of nanosecond single-pulse laser generator, what are the differences and advantages between MOPA structure and Q-switched structure? In view of this difficult problem that often puzzles everyone, we will make a simple analysis from the internal structure of the laser generator, the main parameters of output electron optics and the application field.

01Internal structure of laser generator

The basic principle plan of internal structure of MOPA fiber laser generator and Q-switched fiber laser generator is as follows:

Fig. 1 Basic principle plan of MOPA and Q-switched fiber laser generator

The difference between the internal structure of the MOPA fiber laser generator and the Q-switched fiber laser generator depends on the different methods of causing the single pulse seed light signal lamp to be off.

The single pulse seed light of the MOPA fiber laser generator does not light up because the pulse current drives the semiconductor laser integrated IC, that is, the output light light is not light up according to the driving electronic signal. Therefore, it has a strong coordination ability for the main parameters (duty cycle, repetition frequency, single pulse wave pattern and output power, etc.) that cause different single pulse.

The single pulse seed light signal lamp of the Q-switched fiber laser generator does not light up because of the periodic expansion or reduction of the light loss in the resonator, resulting in the pulse laser output, which is simple in structure and has the advantage of price. However, the main parameters of single pulse are limited due to the hazards of Q-switching components.

02Main parameters of output electronic optics

The output pulse width of MOPA fiber laser generator is individually adjustable. The pulse width of the MOPA fiber laser generator can be automatically tuned at will (ranging from 2ns to 500ns). The narrower the duty cycle is, the smaller the thermal hazard area is, and higher machining accuracy can be obtained. The output duty cycle of the Q-switched fiber laser generator cannot be adjusted, and the duty cycle generally does not change when the output is between 80ns and 140ns.

The repetition frequency range of MOPA fiber laser generator is wider. The repetition frequency of MOPA laser generator can achieve high frequency output of MHz. High repetition frequency represents high production and processing efficiency, and MOPA can still maintain peak output power characteristics under high repetition frequency standard. The Q-switched fiber line laser is subject to the working standard of the Q power switch, and the output frequency range is narrow, and the high frequency can only reach~100kHz.

03application area 

The main parameters of the MOPA fiber laser generator can be adjusted to cover a wide range. Therefore, in addition to covering the production and processing applications of the basic nanosecond laser generator, it can also use its unique narrow duty cycle, high repetition rate, and peak output power to complete some distinctive precision machining applications. For example: anodizing surface treatment

3C products are mostly made of lightweight aluminum oxide raw materials. The success of the application of the MOPA laser generator to mark the surface of raw materials with gray and black color by using the main parameters of narrow duty cycle and high repetition rate is a milestone in its explosive growth. Moreover, it can carve different gray scale actual effects according to different main parameter composition. Similarly, aluminum oxide metal sheet surface stripping is also used. Selecting the main parameters of the narrow duty cycle of the MOPA fiber laser generator can remove the anodic oxide layer at the peak output power, reduce the thermal convection and heat accumulation, make the raw material not easy to deform, and make the background of the shading more detailed and white.

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