Abstract: A polarization-independent orbital angular momentum modulator based on a chiral fiber grating, a method for manufacturing the same, and an orbital angular momentum beam generator. The orbital angular momentum modulator includes an optical fiber body having a spiral fiber structure, and the spiral fiber structure has a long-period optical fiber grating effect. The optical fiber body has a periodic spiral refractive index modulation in an axial direction. A period of the spiral refractive index modulation has a magnitude of hundreds of microns, and the spiral refractive index modulation is distributed in an axial direction, a radial direction, and an angular direction of the optical fiber body, and configured to excite a spiral phase to generate an orbital angular momentum beam.

Abstract: A polarization-independent orbital angular momentum modulator based on a chiral fiber grating, a method for manufacturing the same, and an orbital angular momentum beam generator. The orbital angular momentum modulator includes an optical fiber body having a spiral fiber structure, and the spiral fiber structure has a long-period optical fiber grating effect. The optical fiber body has a periodic spiral refractive index modulation in an axial direction.

Abstract: A method for determining a service area corresponding to a provider communication account includes determining candidate communication accounts that have communicated with the provider communication account within a historical time period of a preset time length, acquiring geographical positions corresponding to the candidate communication accounts, and determining a service area corresponding to the provider communication account according to the geographical positions.

Abstract: A method for determining a service area corresponding to a provider communication account includes determining candidate communication accounts that have communicated with the provider communication account within a historical time period of a preset time length, acquiring geographical positions corresponding to the candidate communication accounts, and determining a service area corresponding to the provider communication account according to the geographical positions.

Abstract: The present disclosure relates to a method and a device for identifying a telephone call. The method includes: determining whether a second telephone of an assigned entity, which entity a telephone number of a caller is affiliated with, is calling a telephone number of a first telephone, when the caller is calling the telephone number of the first telephone, wherein the telephone number of the second telephone is the telephone number used by the caller; when the second telephone is not calling the telephone number of the first telephone, outputting prompt information, wherein the prompt information is for indicating that the telephone call from the caller is a number-falsified telephone call. The present invention may correctly identify whether a telephone call is a number-falsified telephone call.

Abstract: The present disclosure relates to a method and a device for identifying a telephone call. The method includes: determining whether a second telephone of an assigned entity, which entity a telephone number of a caller is affiliated with, is calling a telephone number of a first telephone, when the caller is calling the telephone number of the first telephone, wherein the telephone number of the second telephone is the telephone number used by the caller; when the second telephone is not calling the telephone number of the first telephone, outputting prompt information, wherein the prompt information is for indicating that the telephone call from the caller is a number-falsified telephone call. The present invention may correctly identify whether a telephone call is a number-falsified telephone call.