Multi-mode pump laser based multi-wavelength entangled photon pair generation device and quantum key distribution network configuration method using the same

A multi-wavelength entangled photon pair generation device comprising:

• a multi-mode pump laser that radiates a broadband pump laser beam in an ultraviolet wavelength range including multiple Gaussian-distributed wavelengths;
• a nonlinear crystal that generates a multi-wavelength de-multiplexed entangled photon pair in a near-infrared wavelength range including multiple wavelength components corresponding to multiple Gaussian-distributed wavelengths of the broadband pump laser beam, respectively;
• a temperature controller that adjusts a temperature of the nonlinear crystal;
• and
• a Sagnac interferometer that separates the broadband pump laser beam into two paths such that beams of the two paths are incident on both sides of the nonlinear crystal while facing each other to generate the multi-wavelength de-multiplexed entangled photon pair traveling in opposite directions,
• wherein the Sagnac interferometer includes:
• an interferometer polarization beam splitter that splits the broadband pump laser beam into two paths at a ratio of 50:50;
• a first double-coated mirror and a second double-coated mirror disposed so as to reflect the beams of the two paths such that the beams of the two paths separated by the interferometer polarization beam splitter travel in opposite directions and face each other;
• and
• an interferometer half-wave plate positioned between the interferometer polarization beam splitter and the first double-coated mirror.