As an overview, these are the main documents that will be required to submit to the Graduate College:

Transcripts: Original transcript from each college or university attended (all transcripts submitted to the Graduate College must be official with the college's or registrar's original seal and should show any degrees completed).
Resume/Vitae: Submit a Resume or Curriculum Vitae of your academic and professional backgrounds and experiences (1-2 pages).
Statement of Purpose: Submit a statement, in your own words, of your background, academic preparation, reasons for pursuing a degree in Physics or Photonics, and career aspirations (1-2 pages).
Recommendations: Names and contact information of three (3) persons familiar with the applicant's academic preparation to pursue a degree in Physics or Photonics, and/or job-related skills in these fields.
English Proficiency (for International Students): All persons for whom English is a second language are required to present proof of English competency.
An official TOEFL score of at least 90 (internet based test) is required to be submitted. The TOEFL institution code for OSU is 6546.
Alternatively, an official IELTS, academic stream, examination with a minimum overall band score of 7.0 will satisfy the English proficiency requirements for admission to a graduate program.
Either examination must have been taken within the last two years. Outstanding applicants with official TOEFL scores of 79-90 or IELTS scores of 6.5-7.0 will also be considered for admission into the graduate programs.
Although the Graduate College does not require proof of English proficiency for an applicant who has or will have completed a baccalaureate or graduate degree from a college or university where English is the primary teaching language, and which is located in a country where English is a primary language, the applicant may still need to submit a TOEFL or IELTS score to the Physics Department for employment as a Teaching Assistant.
Please check the complete requirement description on the Graduate College English Proficiency page.
GRE: General GRE is required and the subject (Physics) test is strongly recommended. There are no minimum scores expected of acceptable applicants.