OPTICAL FIBER AMPLIFIER FOR LONG DISTANCE QUANTUM CRYPTOGRAPHY COMMUNICATION AND METHOD THEREFOR, PARTICULARLY RELATED TO INCREASING TRANSMISSION DISTANCE IN QUANTUM CRYPTOGRAPHY COMMUNICATION

摘要

PURPOSE: An optical fiber amplifier for long distance quantum cryptography communication and a method therefor are provided to increase a transmission distance of photons in quantum cryptography communication by amplifying optical strength of the photons encoded and transmitted for quantum cryptography without a polarization change of the photons. CONSTITUTION: A quantum cryptography allocation key transmitting unit(10) encodes linearly polarized photons according to a designated code protocol, and transmits the encoded photons of certain bits to optical fibers. A polarization control unit(20) controls the polarization of the transmitted photons. An optical fiber amplifying unit(30) selectively amplifies only optical signals of specific polarization among optical signals applied from the polarization control unit(20). A polarization selection control unit(40) outputs a polarization control signal to the polarization control unit(20) to optionally control polarization of the photons, and transmits a degree of controlled polarization to a quantum cryptography allocation key receiving unit(50). The quantum cryptography allocation key receiving unit(50) receives the amplified photons and finds out a photon progression having the same bit value among the received photon bits and the photon bits transmitted from the quantum cryptography allocation key transmitting unit(10) by using the polarization state of the received photons and the degree of controlled polarization.