A Novel Light Routing Device with Phase Encoding using Liquid Crystal Spatial Light Modulator

提出了一种新型的空间变量光互连，其中节点之间的空间布线图案只需改变嵌入在空间光调制器(SLM)上的相位编码图案来改变，并通过实验测试了其一维路由图案的基本性能。利用分段的液晶SLM来整形相干光的空间相位分布，使得远场图案与所需的路由图案匹配。同时，用M系列编码对激光光束进行编码，并将其转换为准噪声空间图案。用不同的M系列编码的各种路由模式被多路复用并在空间中发送。在接收器处，只能使用相同的M系列相位掩码来选择所需的布线图案。其余的多路复用信号仍然是噪声，并被一些阈值检测器消除。通过理论和实验研究，我们得到了以下结论：(1)假设一个128×128分段的SLM在16个灰度级，使用长度为127M系列的相位码可以多路复用100多个布线图案。(2)用128个一维SLM和HeNe激光器进行了概念验证实验。利用另一个SLM相位掩码成功地解码了嵌入在SLM上的双编码空间布线图案。对于不同的M序列编码长度，评估了信损比。(3)我们证明了非相干光的光谱相位编码的空间图案可以通过光纤传输，并通过形成光谱全息术来恢复。这种时空转换方案可以开辟新的光互连和通信。(4)为了将光谱全息技术用于光纤传输的互连和通信，我们展示了1.3 mm波长的全息。全息图首先用1.3 mm倍频激光写入，然后用基波光束读出。

A novel space variant optical interconnection, where the spatial routing pattern among nodes is variable only by changing the phase encoding pattern embedded on a spatial light modulator (SLM), is proposed and experimentally examined its basic performance for one-dimensional routing patterns. The spatial phase profile of a coherent light is shaped with a segmented liquid crystal SLM so that the far-field pattern matches to a desired routing pattern. At the same time, the laser beam is encoded with a M-series code and converted to a quasi noise spatial pattern. Various routing patterns encoded with different M-series are multiplexed and send in space. At a receiver, only a desired routing pattern can be selected with an identical M-series phase mask. The rest of multiplexed signals remain as noise and eliminated by some threshold detectors. We obtained following conclusions through theoretical and experimental studies.(1) Assuming a 128x128 segmented SLM at 16 gray levels, one can multiplex more than 100 routing patterns using length-127 M-series phase codes.(2) Proof-of-concept experiments was conducted with a 128 one-dimensional SLM and a HeNe laser. Doubly encoded spatial routing pattern embedded on the SLM was successfully decoded with another SLM phase mask. The signal-to-loss ratio were evaluated for different M-series code lengths.(3) We demonstrated that a spatial pattern encoded for the spectral phase of an incoherent light can be sent through a fiber and recovered by forming a spectral holography. This time-to-space conversion scheme can open up new optical interconnections and communications.(4) In order to use spectral holography technologies in fiber delivered interconnections and communications, we demonstrated holography at 1.3mm wavelength. The hologram was first written by a SHG of 1.3mm laser and then read by the fundamental beam.