Abstract: Embodiments of this application disclose a data transmission method and apparatus, a device, and a storage medium, and relate to the field of optical communication technologies. In a coherent optical transmission system with dual-polarization transmission and single-polarization reception, a transmit end sends a data frame including a subframe including reference pilot information, a data unit, and a corresponding redundant code, where a 1st subframe in each data frame includes more reference pilot symbols than other subframes. A receive end performs parameter adjustment on a correction function based on pilot information and the reference pilot information in the received data frame.

Abstract: An asymmetric coherent receiver includes an optical front end configured to split a received optical signal into two paths, wherein the split received optical signal experiences a different optical transfer function in one of the two paths; two photodetectors each configured to detect power one of the split received optical signals in each of the two paths to obtain corresponding electrical signals; and circuitry configured to perform electrical domain extraction of information of each of the corresponding electrical signals from the two paths, wherein the different optical transfer function provides additional information utilized in optical field reconstruction via direct detection.

Abstract: An asymmetric coherent receiver includes an optical front end configured to split a received optical signal into two paths, wherein the split received optical signal experiences a different optical transfer function in one of the two paths; two photodetectors each configured to detect power one of the split received optical signals in each of the two paths to obtain corresponding electrical signals; and circuitry configured to perform electrical domain extraction of information of each of the corresponding electrical signals from the two paths, wherein the different optical transfer function provides additional information utilized in optical field reconstruction via direct detection.

Abstract: A method for preparing an iminodisuccinate chelating agent, wherein a reaction comprising raw material A, raw material B, an alkali metal hydroxide, and water is carried out under ambient pressure, and at a pH in the range of 6-12 and a reaction temperature ranging from 65° C. to a boiling reflux temperature, and the mixed liquid obtained after the reaction is a mixture containing the iminodisuccinate chelating agent. The raw material A is a compound capable of obtaining a maleate through alkaline hydrolysis; and the raw material B is a compound capable of obtaining an aspartic acid through alkaline hydrolysis. With mild reaction conditions, a short reaction time and a high reaction yield, the preparation method is able to shorten the production process, improve the production efficiency, and reduce the production cost, and it is truly a preparation method which is highly efficient, environmentally friendly, and extremely suitable for industrial scale production.

Abstract: A method for preparing an iminodisuccinate chelating agent, wherein a reaction comprising raw material A, raw material B, an alkali metal hydroxide, and water is carried out under ambient pressure, and at a pH in the range of 6-12 and a reaction temperature ranging from 65° C. to a boiling reflux temperature, and the mixed liquid obtained after the reaction is a mixture containing the iminodisuccinate chelating agent. The raw material A is a compound capable of obtaining a maleate through alkaline hydrolysis; and the raw material B is a compound capable of obtaining an aspartic acid through alkaline hydrolysis. With mild reaction conditions, a short reaction time and a high reaction yield, the preparation method is able to shorten the production process, improve the production efficiency, and reduce the production cost, and it is truly a preparation method which is highly efficient, environmentally friendly, and extremely suitable for industrial scale production.