A RECEIVER FOR RECEIVING INFORMATION TRANSMITTED USING VERY WEAK LIGHT PULSES AND A METHOD FOR TRANSMITTING INFORMATION USING VERY WEAK LIGHT PULSES

摘要

The object of the invention is a receiver for receiving information using very weak light pulses, which comprises an input, optical elements and a detector (SPD), wherein it comprises at least one module (T), which comprises at least one polarisation splitting element, an element with a different optical path length for each of the split polarisations, and at least one plate rotating the polarisation (HWP, QWP) wherein part of the optical signal following a shorter, and part of it a longer optical path length wherein polarisation splitting element is a polarisation beam splitter (PBS) cube, and the element with a different optical path length for each of the split polarisations is placed between two polarisation beam splitter (PBS) cubes, and the module (T) comprises at least one polarisation modulator (PoIM).;The object of the invention is also a method for transmitting information using very weak light pulses, wherein in the receiver a light pulse having at least two different polarisations splits into at least two optical signals with different polarisations; subsequently, the signal with one of the split polarisations is delayed with respect to the optical signal with other polarisation, upon which the signals are merged and undergo amplification due to interference, wherein subsequently the signals are recorded in a detector (SPD), and wherein prior to splitting at least one light pulse with at least two different polarisations from a sequence of pulses, its polarisation is rotated using a polarisation modulator (PoIM), regardless of the input sequence, by +90° or -90°.