Hi there,
We're sorry about the trouble with Photoshop due to the pixelation of your image.
In the example you have shared, the document is only 820 px X 312 px and zoomed in to over 300%. At such a zoom level for smaller documents, pixelation of edges is expected. Do you face issues with larger documents as well? What is the size of the paper that you are printing the file to? Are you printing to scale of selecting the option to fit the image to the paper size?
Regards,
Nikunj