http://www.researchgate.net/post/Can_solid_Immersion_LensSIL_convert_evanescent_light_to_propagating_light
Takashi Hira · Keio University

Dear Mr. Ullah,　I'm male. And are you a student? If so, you have to describe "Ph.D candidate" or "Ph.D student".

"Ph.D researcher" means "I've already got Ph.D degree and I've been hired by some research institute."