DWDM QKD Transmission via Wavelength Segmentation
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Solution Overview
Problem
Quantum-key distribution (QKD) signals are more sensitive to attenuation than data signals during optical fiber transmission, making existing methods for simultaneous data and QKD transmission over the same fiber unreliable and limited in range.
Innovation Solution
The system employs optical phase conjugation to shift data signals from a low-loss wavelength band to another wavelength band, freeing up the original band for QKD transmission, thereby optimizing attenuation characteristics for QKD signals and using existing commercial equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If QKD keys are transmitted at 1.3 um wavelength, then interference with data transmission is reduced, but attenuation increases and QKD reliability deteriorates
Solution Approach 1:
The patent changes the wavelength parameter of data transmission from 1.5 um to 1.3 um, allowing QKD to operate at the optimal 1.5 um wavelength with lower attenuation while data operates at 1.3 um where interference is minimized. This parameter separation resolves the contradiction between interference reduction and reliability.
Solution Approach 2:
The patent segments the optical spectrum into distinct wavelength bands: 1.5 um for QKD and 1.3 um for data transmission. This spectral segmentation allows each signal type to operate in its optimal wavelength range without mutual interference, simultaneously achieving low attenuation for QKD and interference reduction.
2Loss of energy
If both QKD keys and data are transmitted at 1.5 um wavelength, then attenuation is minimized for both signals, but interference between channels increases
Solution Approach 1:
The patent segments the transmission system into two distinct wavelength channels: QKD operates at 1.5 um to minimize attenuation, while data operates at 1.3 um to avoid interfering with the QKD signal. This segmentation allows each channel to optimize for its primary requirement without compromising the other.
Solution Approach 2:
The patent uses wavelength division multiplexing as an intermediary mechanism to separate QKD and data signals in the frequency domain. By assigning different wavelengths to each signal type, the system allows both to coexist on the same fiber without direct interference, while QKD retains access to the lower-loss 1.5 um band.
3Object-generated harmful factors
If data channel power levels are reduced to limit interference, then QKD channel protection is improved, but data transmission reliability deteriorates
Solution Approach 1:
The patent changes the wavelength parameter of data transmission from 1.5 um to 1.3 um, allowing data to maintain higher power levels without interfering with QKD. This parameter change eliminates the need to reduce data power, thereby maintaining data transmission reliability while still protecting the QKD channel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the transmission range and reliability of QKD systems by approximately 50% while maintaining viable data transmission, and can be implemented in modified commercial networks using standard optical communication equipment.
Implementation Method 1
The optical path attenuates signals at a first wavelength less than it attenuates signals at a second wavelength
Implementation Method 2
The system employs optical phase conjugation to shift data signals from a low-loss wavelength band to another wavelength band
Data Source
AI summary
An optical data transmission system and method for, at an optical transmitter, converting to a second wavelength, an optical data signal at a first wavelength; transmitting at the second wavelength, the optical data signal to an optical receiver over an optical path; and transmitting at the first wavelength, to the receiver over the path a single-photon signal comprising a stream of single photons. The optical path is configured to carry optical signals at different wavelengths and the optical path attenuates signals at the first wavelength less than the optical path attenuates signals at the second wavelength. The optical data transmission system and method for, at the receiver, receiving the single-photon signal at the first wavelength and receiving the optical data signal at the second wavelength; and converting the optical data signal to the first wavelength for detection.