Zhu Guoxuan, Bai Zhiyong, Chen Jiayan, Huang Churou, Wu Luping, Fu Cailing, Wang Yiping
Opt Express. 2021 Aug 30;29(18):28452-28460. doi: 10.1364/OE.430882.
Optical orbital angular momentum (OAM) has been recently implemented in holography technologies as an independent degree of freedom for boosting information capacity. However, the holography capacity and fidelity suffer from the limited space-bandwidth product (SBP) and the channel crosstalk, albeit the OAM mode set exploited as multiplexing channels is theoretically unbounded. Here, we propose the ultra-dense perfect OAM holography, in which the OAM modes are discriminated both radially and angularly. As such, the perfect OAM mode set constructs the two-dimensional spatial division multiplexed holography (conventional OAM holography is 1D). The extending degree of freedom enhances the holography capacity and fidelity. We have demonstrated an ultra-fine fractional OAM holography with the topological charge resolution of 0.01. A 20-digit OAM-encoded holography encryption has also been exhibited. It harnesses only five angular OAM topological charges ranging from -16 to +16. The SBP efficiency is about 20 times larger than the conventional phase-only OAM holography. This work paves the way to compact, high-security and high-capacity holography.
光学轨道角动量（OAM）最近已在全息技术中作为一种独立的自由度得以应用，用于提高信息容量。然而，尽管理论上作为复用通道所利用的OAM模式集是无界的，但全息容量和保真度仍受到有限的空间带宽积（SBP）和通道串扰的影响。在此，我们提出了超密集完美OAM全息术，其中OAM模式在径向和角向都能被区分。这样，完美的OAM模式集构建了二维空间分割复用全息术（传统的OAM全息术是一维的）。扩展的自由度提高了全息容量和保真度。我们已经展示了一种拓扑电荷分辨率为0.01的超精细分数OAM全息术。还展示了一种20位OAM编码的全息加密技术。它仅利用了五个从 -16到 +16的角向OAM拓扑电荷。SBP效率比传统的仅相位OAM全息术大约大20倍。这项工作为紧凑、高安全性和高容量全息术铺平了道路。
