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

提出了一种新颖的空间可变光互连结构，通过改变空间光调制器（SLM）上的相位编码图案来改变节点间的空间布线图案，并通过实验研究了其一维布线图案的基本性能。相干光的空间相位轮廓用分段液晶SLM成形，使得远场图案与期望的路由图案匹配。同时，激光束用M系列编码并转换成准噪声空间图案。用不同的M系列编码的各种路由模式被复用并在空间中发送。在接收器处，仅可以利用相同的M系列相位掩模来选择期望的布线图案。其余的复用信号作为噪声保留下来，并通过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)假设在16个灰度级处的128 × 128分段SLM，可以使用长度为127的M系列相位码来复用超过100个布线图案。(2)用128一维SLM和HeNe激光器进行了概念验证实验。用另一个SLM相位掩模成功解码了SLM上的双重编码空间布线图。对不同M系列码长的信损比进行了评估。(3)我们证明了一个空间模式编码的光谱相位的非相干光可以发送通过光纤和恢复形成光谱全息。这种时空转换方案可以开辟新的光互连和通信。(4)为了在光纤传输互连和通信中使用光谱全息技术，我们演示了1.3 mm波长的全息术。全息图先用1.3mm的二次谐波激光写入，再用基波光读出。

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.