An expanded beam optical connector including a connector body, an optical element in the form of a waveguide or active device, a beam width altering optical lens, and a transmit/receive window. The optical element, the beam width altering optical lens, and the transmit/receive window are configured such that optical signals propagate between the optical element and the transmit/receive window via the beam width altering optical lens. The transmit/receive window includes an optical medium that forms an interior surface of the transmit/receive window, an optical transition layer between the interior surface formed by the optical medium, and a protective layer forming an exterior surface of the transmit/receive window. The connector body is configured to place the exterior surface of the transmit/receive window in close contact with a mating exterior surface of a mating transmit/receive window of a complementary optical device to define a close contact portion.