Phase-retrieval (PR) receivers can reconstruct complex-valued signals using only direct detection without the use of any optical carriers. We propose and demonstrate two PR receiver solutions with faster and better convergence. First, we demonstrate a PR receiver based on parallel alternative projections that are produced by propagating the signal through an array of dispersive elements of increasing length followed by direct detection. Fast convergence and high retrieved phase accuracy are achieved using a modified Gerchberg-Saxton (GS) algorithm that uses each projection as an intensity constraint. Second, we achieve similar performances employing an enhanced single projection GS algorithm with selective phase reset using symbol-wise GS errors. We experimentally reconstruct a 30 Gbaud QPSK signal after 55 km single-mode fiber transmission using the proposed solutions with a reduced number of iterations.

中文翻译：

---

具有快速收敛的相位检索，采用并行替代投影和相位重置进行相干通信。

相位检索（PR）接收机仅使用直接检测即可重建复数值信号，而无需使用任何光学载波。我们提出并演示了两种具有更快更好融合的PR接收器解决方案。首先，我们演示了基于并行替代投影的PR接收器，该投影是通过将信号传播通过长度不断增加的色散元件阵列然后直接检测而产生的。使用改进的Gerchberg-Saxton（GS）算法（使用每个投影作为强度约束）可以实现快速收敛和高检索相位精度。其次，我们使用增强的单投影GS算法以及使用逐符号GS误差的选择性相位重置来实现类似的性能。