Hello Rks,

No, Phd is not must for have a good career . If you have a master degree in photonics and have a good experience in this field then then you might not require any phd degree . So go for experience first and opt field works as much as you can that helps you in increment in your experience in the field .

You can go for the companies like KLA-Tencor and Applied materials look for Application engineers with knowledge on photonics and semiconductors.

Hope it helps.

Thank you :)