Synchronous position two-photon interference of random-phase grating.

By generalizing the phase structure of the random-phase grating we recently designed [Opt. Express21, 14056 (2013)OPEXFF1094-408710.1364/OE.21.014056], we show that non-HBT type (synchronous position) two-photon grating interference can be obtained, which physically relies on groups of multiple indistinguishable two-photon paths modulated by the spatial distributions of phase modes. By properly selecting the random-phase structures, synchronous position subwavelength interference can be obtained, the period of which, in the two-photon interference domain, is decreased by a factor N (=3,4,5,6,…), depending on the slit number and random-phase structure, and the visibility of N-fold subwavelength interference fringes could be improved by increasing the slit number of the grating. The results show that modulation on two-photon paths via spatial arrangements of the phase modes offers the possibility to actively control the optical high-order coherence in the same optical scheme.