The answer strongly depends on your previous education. You should have a Bachelor's (B.Sc.) degree in Physics or Engineering Sciences. In the latter case, eligibility will strongly depend on your background in physics and mathematics. If you have a Bachelor's degree in Computer Sciences, Computer Engineering or Telecommunication Engineering you might also be an eligible candidate for studying in the Master's degree program. Please emphasize in this case your experiences in the field of optics or photonics within your academic education or your professional career in your Curriculum Vitae as well as in your Letter of Motivation.