So when will china deploy practical laser guns in warships? Any idea or suggestions?
PLAN already deploys a wide range of laser dazzler systems if that's what you are asking. As for high energy laser systems, I suspect PLAN does not deem them so desperately needed to warrant formal adoption at this stage. Also, probably only the Type 055 generates enough power to have some left for HELs.
And if I am allowed to make an observation on DDG(X)... I highly doubt a notional DDG(X), if sufficiently near adoption, would deploy the kinds of HEL in your mind. In fact much of what's in that notional DDG(X) proposal would probably not be adopted. This particular CG was proposed a while ago when the design was much more optimistic.
At the moment where we stand, DDG(X) has already been confirmed to be a barebone version of the proposed one. For one, we aren't even sure it would be equipped with a similar IPS system on the Zumwalt class let alone an IPES system. Afaik, DDG(X) will continue to use a COGAG system albeit with 4 LM2500+G4 GTs. Its combat systems and hardware will also pretty much be the same as Flight III Burkes.
I am not saying it won't have the kinds of power to use HELs as 055 is a COGAG platform as well, I just highly doubt USN would be as ambitious if they are in a hurry... which... mind you, even if they are, DDG(X) timelines have been pushed all the way back to 2039 in the 2025 CBO report...
I am off topic a bit but what I am saying essentially is you are looking at a version of DDG(X) that is extremely optimistic and more of a "concept ship" with a wishlist of capabilities and then comparing them to platforms in service. There really isn't a noteworthy comparison.