Injection-Locked Laser Source for Quantum Encoding Stability
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Solution Overview
Problem
Conventional encoding devices for time-bin phase encoding suffer from instability in basis stability, key rate, and transmission efficiency due to environmental factors, requiring frequent feedback and increasing system costs, especially in long-distance communication.
Innovation Solution
A light source comprising a master and slave laser system using injection locking and internal modulation techniques to generate pulses with a stable time and phase relation, eliminating the need for additional feedback mechanisms and reducing system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional encoding devices for time-bin phase encoding are used, then the system can perform quantum key distribution, but the basis stability, key rate, and transmission efficiency become unstable due to environmental factors, requiring frequent feedback mechanisms
Solution Approach 1:
The laser pulse source performs self-modulation through injection locking, where the master laser pulse automatically modulates the slave laser pulse without requiring external feedback mechanisms. This self-service approach eliminates the need for complex feedback systems while maintaining stable time-bin and phase encoding, directly resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent replaces mechanical feedback control systems with an optical injection locking mechanism. The master laser pulse optically locks the slave laser pulse, substituting complex mechanical feedback adjustments with a simpler optical coupling mechanism, thereby improving basis stability while reducing device complexity
2Reliability
If feedback mechanisms are added to improve stability, then basis stability improves, but system cost and complexity increase
Solution Approach 1:
The patent merges the master laser and slave laser into a single integrated pulse source system. The master laser pulse and slave laser pulse work together in an injection locking configuration, combining their functions to achieve stable key rate and phase encoding without requiring separate feedback control systems, thus improving reliability while reducing system complexity
Solution Approach 2:
The slave laser pulse serves multiple functions simultaneously: it carries the quantum information, maintains phase coherence through injection locking, and provides time-bin encoding. This multi-functionality eliminates the need for additional dedicated components for each function, reducing system complexity while maintaining key rate stability
3Manufacturing precision
If additional feedback mechanisms are implemented, then encoding stability improves, but transmission efficiency decreases due to system complexity
Solution Approach 1:
The master laser pulse performs preliminary modulation on the slave laser pulse through injection locking before the quantum information is encoded and transmitted. This preliminary action establishes stable time-bin and phase relationships in advance, ensuring encoding precision without requiring additional feedback during transmission, thereby maintaining high transmission efficiency
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 provides high stability and extinction ratio for time-bin encoding and phase encoding, enhancing key rate stability and transmission efficiency while simplifying the encoding device structure and reducing costs.
Implementation Method 1
the slave laser is configured to output a slave laser pulse in response to a slave drive signal from a slave drive signal source, to encode a signal light pulse... generated under stimulation of a pulse component of the master laser pulse
Data Source
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Figure 3A~3B
Figure 4A~4B
AI summary
Provided are a light source for use in the field of quantum communication, and an encoding device using the light source. When a light source of the present invention is applied to Z basis vector encoding, a high and stable extinction ratio can be provided, and two consecutive optical pulses having a stable phase relation can be provided for encoding under an X basis vector.