Time-space conversion system for analog transmission of holograms through single-mode fibers

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Transmission of parallel data arrays with complex amplitude, which distribute in a two-dimensional space and also temporally vary, e.g., a dynamic hologram with ultra high spatial resolution and many gray levels, through a single-mode optical fiber is a challenging task. A coherent technique would be suitable to transmit both the amplitude and phase without analog-digital conversion. The conversion of temporal information into one-dimensional spatial information by writing a spectral hologram of the pulse and reading it out with a continuous-wave laser, and the inverse process, i.e., the conversion of one dimensional spatial patterns into temporal patterns (pulse shaping) with a 4-f optical arrangement would lead to a novel analog transmission scheme for both phase and amplitude of one-dimensional spatial data through a single-mode fiber. In this study, we experimentally examined several schemes based on the time-space conversion and obtained the conclusions as follows:(1) Transmission … More of one-dimensional spatial phase information by low-coherence light through a single-mode fiber is experimentally demonstrated by use of space-time conversion at a 4-f Fourier coherence function shaper and time-space conversion with spectral holography. Space-time coupling caused by the transmitter limits the capacity of information transmittable with one coherence function shaping.(2) A new scheme for two-dimensional parallel data transmission with a femtosecond laser pulse through a single-mode fiber, which is based upon one-dimensional space-time conversion technique in conjunction with code division multiple access, is implemented and numerically demonstrated. Two-dimensional digital images in a 16 bits x 16 bits plane are successfully transmitted by a single femtosecond laser pulse at an equivalent transmission rate of 1.6 Tbit/s and recovered by spectral holography.(3) An all-optical packet router was proposed and its basic function was experimentally demonstrated The optical router consisting of angularly multiplexed spectral hologram works by routing the data stream, which is convoluted its own M-sequence code, to the pre-defined diffraction angle. Less