Time division interferometer setups

A time division interferometer (TDI) in the optical regime is presented, where a wavetrain is temporally split into two distinct parts that are superimposed at a subsequent stage. At any one time, the photons have no alternatives, only one possible path is possible. There is no path bifurcation in the setup, i.e. no ‘Y’ where the photons can take left or right. The photons choice, if any, is to arrive/collapse before or after the time t1 when the time modulated medium changes its state. In time-varying media, as energy can be exchanged between the wave and medium, the wave frequency is modified. Thus, the diverted photons become doubly tagged, in their wave vector direction as well as their frequency. A streak camera detector array resolves both, the fringe pattern as well as the frequency beats, in a space versus time interferogram. This apparatus has temporal resolution and spatial resolution. Several TDI configurations are described, two of them are implemented: a spatio-temporal interferometer where the ‘which path’ criterion is readily observed and an all temporal TDI where only temporal interference is present. Novel possibilities of TDI schemes are discussed.