Transient behaviors in a spectrum-tailored all-PM NALM mode-locked fiber laser.

We demonstrate an all-polarization-maintaining (PM) dispersion-managed mode-locked ytterbium-doped fiber oscillator based on a nonlinear amplifying loop mirror (NALM). Experimentally, three mode-locking regimes with distinct tailored spectra are achieved with carefully designed cavity setup and adjusted pump power. Using the dispersive Fourier transformation (DFT) technique, the real-time transition dynamics among these regimes are observed as the pump power decreases.

Associations between PM, ambient heat exposure and congenital hydronephrosis in southeastern China.

Objectives: This research aims to analyze how exposure to fine particulate matter (PM5) and ambient heat during pregnancy increases the risk of congenital hydronephrosis (CH) in newborns.

Methods: A case-control study was conducted to investigate the relationship between exposure to PM and ambient heat during pregnancy and the occurrence of CH in newborns. The study, which was conducted from 2015 to 2020, included 409 infants with CH as the case group and 409 infants without any abnormalities as the control group.

Association between gestational exposure and risk of orofacial clefts: a systematic review and meta-analysis.

Background: The occurrence of orofacial Clefts (OFCs) is a congenital disease caused by many factors. According to recent studies, air pollution has a strong correlation with the occurrence of OFCs. However, there are still some controversies about the current research results, and there is no relevant research to review the latest results in recent years.

Association between air pollutants and birth defects in Xiamen, China.

Objective: To explore the relationship between common air pollution and common birth defects, and to provide reference for the prevention of birth defects.

Methods: We conducted a case-control study in Xiamen, a city in southeastern China from 2019 to 2020. Logistics regression was used to analyze the relationship between sulfur dioxide(SO), fine particulate matter 2.

Active phase locking of thirty fiber channels using multilevel phase dithering method.

An active phase locking of a large-scale fiber array with thirty channels has been demonstrated experimentally. In the experiment, the first group of thirty phase controllers is used to compensate the phase noises between the elements and the second group of thirty phase modulators is used to impose additional phase disturbances to mimic the phase noises in the high power fiber amplifiers. A multi-level phase dithering algorithm using dual-level rectangular-wave phase modulation and time division multiplexing can achieve the same phase control as single/multi-frequency dithering technique, but without coherent demodulation circuit.

Phase locking of slab laser amplifiers via square wave dithering algorithm.

An active phase locking of slab laser amplifiers via square wave dithering algorithm is demonstrated experimentally. The MPD technique based on dual-level square wave phase modulation, time division multiplexing, and single detector can achieve the phase error signal of amplifiers, but without coherent demodulation process. The experimental investigation on the 208 W coherent beam combining of two slab amplifiers shows that the whole system in a closed loop performs well over a long time observation.

Fiber polarization control based on a fast locating algorithm.

In this article, currently used feedback control algorithms used in the polarization controller, including a simulated annealing algorithm and a gradient algorithm, are analyzed. On this basis, a new method of polarization control feedback algorithm based on a fast locating algorithm is proposed to solve the defects of the original algorithm, such as poor convergence and an extensive time consuming search. It can reduce convergence time and improve the response speed of the polarization controllers.