Inside Hybrid S-MOPA Lasers (And Benefit Claims)

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Inside Hybrid S-MOPA Lasers (And Benefit Claims)

by Joshua Christley
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Inside look at hybrid laser technology

As a relatively new solution for the marking and traceability world, hybrid laser technology is still a new frontier for many OEMs. What are hybrid lasers? Fundamentally, “hybrid” describes diode-pumped solid state lasers that have been modified with the goal of improving its performance, such as an S-MOPA laser (Solid-State Master Oscillator Power Amplifier).


S-MOPA Diagram
 

The S-MOPA components (shown in the diagram), which include a traditional vanadate (YVO4) laser in the green rectangle and a fiber-based amplifier that uses a second YVO4 vanadate crystal along with fiber technology in the red.  The laser beam propagation is still in free space based on the vanadate oscillator, using mirrors and output couplers to direct the beam. 

Understand the Technology: Dissecting the Hybrid Claims

At its core, a hybrid laser is a solid-state vanadate laser combined with another vanadate fiber-based amplifier. With 16 years of experience in laser marking, including 10 years with optics and laser sources and six years as an applications engineer with MECCO, I have a deep understanding of both YVO4 and fiber laser technologies.

I performed extensive research on the claim that combining YVO4 and fiber into one product will combine the advantages of both systems: 

  1. YVO4 Benefits: Offers high peak power and high beam quality
  2. Fiber Benefits: Delivers high output and long service life

What I learned surprised me. To get a full understanding of this technology, let’s take a look at each of these benefit claims:

YVO4 Benefits: High peak power and high beam quality

From the YVO4 component, the user is promised high peak power and high beam quality. 
 
High peak power is a necessity when marking on plastics for contrast and to control the heat effected zone on metals. This is a proven benefit of vanadate lasers, as well as other diode pumped lasers pumping YAG crystals instead of YVO4. Higher peak power can be very beneficial when the application requires it.
 
High beam quality is typically measured by M2. Most laser systems on the market today average 1M2 and offer virtually the same beam quality. Unfortunately, this data is not listed on the hybrid laser’s spec sheet to know how it measures up.
 

Fiber Benefits: High output and long service life

In This Blog Series

The other claims are more difficult to sort through. Considering that the major components of the laser oscillator are old vanadate technology, both claims of high output and long service life require the question “higher (or longer) than what?”
 
High output can help with faster laser marking. For the hybrid laser, the “high output” is listed as 25W. This is indeed higher than some vanadate models, but vanadate technology is available from multiple vendors anywhere from 6W to 40W. And don’t forget that fiber laser models can go up to 100W of output power and beyond. 
 
Flexibility is another benefit that the hybrid laser claims to offer as part of its high output capabilities.  This is apparently based on the fact that YVO4 vanadate lasers can technically be used in continuous wave or pulsed oscillation methods. The problem with this claim is that continuous wave is rarely, if ever, used for marking applications. True flexibility, where marking on a range of plastics and metals is concerned, is achieved by adjusting the pulse duration settings. 

Lastly, when evaluating the claim of “long service life,” we have to once again ask “longer than what?”  The claim is purposely vague, as the hybrid laser system will not have longer service life than a true fiber laser. What this claim is referring to is the attempt to improve the short lifespan of vanadate crystals and the bad reputation they’ve earned in the industry. 

The question it comes down to is: Can you have your cake and eat it too? If having all of these benefits in one product sounds too good to be true, you should know that you do have other options when it comes to finding a laser solution that will achieve these benefits

MECCO recommends always comparing your options – because marking solutions are not one-size-fits-all.

 Deep Dive: How Hybrid Components Would Impact Service Life

So how could the S-MOPA laser extend the life of short-lived consumable crystals?  It can’t. 

  • Vanadate crystals will still have the same lifespan regardless of what technology is pumping it. Simply adding an amplifier doesn’t eliminate the negatives of vanadate technology. In fact, as the S-MOPA diagram showed, a second vanadate crystal was added in the amplifier.
  • You’ll also notice multiple optical surfaces (approximately 11-12) that can break down, get dirty, fall out of alignment, or fail. Each icon has an “in” and an “out.”  This certainly would not provide a longer service life than a true fiber laser, which has no exposed optical surfaces: all of such are instead fused into the fiber path.
  • Another factor is that all of the optical components are aligned and need to remain aligned.  You can’t mount a vanadate onto a robot due to the possibility of bumping, which would move the alignment of the optics within the laser source. If this happens, absorption and reflection will occur and increase the odds of damage to the laser. 

Therefore, this “longer life” claim raises the biggest red flag for buying the S-MOPA laser. Adding the amplifier to the YVO4 design only makes maintenance that much more difficult and expensive, especially if it’s IP-rated. With all of the optical surfaces inside, hermetically sealing the unit and getting an IP rating is a good idea.

However, it means that the laser would not be able to be repaired in the field and would have to be shipped back to a clean room facility at their factory. This may be fine for simple, low-volume, clean room operations, but it could perhaps cause big issues for large, high-volume manufacturing facilities.

  

 

 

 

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