Auto-Compensating Quantum Cryptography Transceiver for High-Speed Transmission
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Solution Overview
Problem
The transmission rate of auto-compensating quantum cryptography systems is limited due to Rayleigh scattering in optical fibers, causing transmission errors as strong intensity pulses are reflected and detected simultaneously with feedback pulses.
Innovation Solution
Incorporating a wavelength converter and an optical filter in the quantum cryptography transceiver to convert and filter out optical pulse signals affected by Rayleigh scattering, ensuring only one pulse exists in the transmission fiber, thereby overcoming the transmission rate limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a strong intensity optical pulse is transmitted through the optical fiber, then the transmission distance is improved, but Rayleigh scattering causes reflected pulses that are detected simultaneously with feedback pulses resulting in transmission errors
Solution Approach 1:
The patent introduces a wavelength converter as an intermediary device that transforms the strong intensity optical pulse at wavelength λ1 into a weak intensity optical pulse at wavelength λ2. This mediator converts the harmful strong pulse into a usable weak pulse suitable for quantum cryptography, allowing long-distance transmission without Rayleigh scattering-induced errors.
Solution Approach 2:
The patent changes the wavelength parameter of the optical pulse from λ1 to λ2 using a wavelength converter. This parameter change transforms the pulse characteristics, converting a strong pulse that causes Rayleigh scattering into a weak pulse that can be transmitted through the optical fiber without causing detection errors.
2Reliability
If only one optical pulse exists in the transmission fiber to avoid Rayleigh scattering effects, then transmission accuracy is improved, but the transmission rate is limited and affected
Solution Approach 1:
The patent adds a wavelength dimension to the transmission system by using wavelength conversion. Multiple pulses can now coexist in the optical fiber at different wavelengths (λ1 for strong pulses, λ2 for weak pulses), effectively utilizing the spectral dimension to increase transmission rate while maintaining accuracy through proper wavelength management.
Solution Approach 2:
The system uses periodic time-division multiplexing where strong intensity pulses and weak feedback pulses are transmitted at different time intervals. The wavelength converter processes strong pulses during one period, and the optical filter allows weak pulses to pass during another period, enabling continuous high-rate transmission without interference.
3Productivity
If a wavelength converter and optical filter are added to the transceiver, then transmission rate and accuracy are improved, but device complexity increases
Solution Approach 1:
The wavelength converter is designed to perform multiple functions: it converts wavelength from λ1 to λ2, attenuates pulse intensity from strong to weak, and can be integrated with existing optical components. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving improved transmission performance.
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
The solution enables a high-speed auto-compensating quantum cryptography system by removing optical pulse signals caused by Rayleigh scattering, enhancing transmission efficiency and preventing errors.
Implementation Method 1
a wavelength converter converting an optical pulse signal having a first wavelength into an optical pulse signal having a second wavelength
Implementation Method 2
an optical filter removing an optical pulse signal caused by Rayleigh scattering
Implementation Method 3
the transmitted pulses with strong intensity is reflected due to Rayleigh scattering of the transmission optical fiber
Implementation Method 4
a Faraday mirror rotating and reflecting polarized light of the optical pulse signal having the modulated phase
Data Source
AI summary
Provided are an auto-compensating quantum cryptography transceiver and method of transmitting a quantum cryptography key at a high speed. A quantum cryptography transmitter includes a wavelength converter, an optical attenuator, an optical phase modulator, and a Faraday mirror. A quantum cryptography receiver includes a polarization beam splitter, an optical coupler, an optical filter, and a photon detector. Thus, a limit of a transmission rate caused by Rayleigh scattering of an optical fiber can be overcome.