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

具有复杂幅值且分布于二维空间且随时间变化的并行数据阵列，如具有超高空间分辨率和多个灰度级的动态全息图，通过单模光纤传输是一项具有挑战性的任务。相干技术可以同时传输振幅和相位，而不需要进行模数转换。将脉冲的光谱全息图写入连续波激光器读出，将时间信息转换为一维空间信息，将一维空间模式转换为具有4-f光排列的时间模式（脉冲整形），这一反向过程将导致一维空间数据的相位和幅度通过单模光纤的新型模拟传输方案。本文实验研究了几种基于时-空转换的方案，得到了以下结论：(1)利用4-f傅里叶相干函数整形器的时-空转换和光谱全息的时-空转换，实验证明了低相干光通过单模光纤传输更多的一维空间相位信息。发射机引起的时空耦合限制了单相干函数整形的信息传输能力。(2)提出了一种基于一维空时转换技术与码分多址技术相结合的飞秒激光单模光纤二维并行数据传输新方案，并进行了数值验证。利用单飞秒激光脉冲以1.6 Tbit/s的等效传输速率成功地传输了16位x 16位平面上的二维数字图像，并通过光谱全息法恢复了图像。(3)提出了一种全光分组路由器，并对其基本功能进行了实验验证。该全光分组路由器由角度复用的光谱全息图组成，其工作原理是将经过自身m序列码卷积的数据流路由到预定的衍射角。少

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