Fibre Communication Polarization Compensation for Reliable Interference
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Solution Overview
Problem
Existing fibre-based communication systems face challenges in maintaining consistent polarization states of optical signals due to birefringence in fibres, leading to inefficiencies in quantum key distribution and encryption key distribution over long distances.
Innovation Solution
Implementing dual-rail encoding on two waveguides with phase and amplitude adjustments, using laser sources injection locked to the same frequency, and pre-compensating for fibre-induced polarization rotations at the emitter side, allowing optical signals to arrive at the receiver with the same polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual-rail encoding is implemented on two waveguides with phase and amplitude adjustments, then polarization consistency is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-compensating for fibre-induced polarization rotations at the emitter side before light enters the fibre. The dual-rail encoders are controlled using compensation adjustment information to pre-adjust the polarization states, so that when light travels through the birefringent fibre, the polarization consistency is maintained at the receiver end.
Solution Approach 2:
The patent implements feedback by obtaining compensation adjustment information concerning the fibres and using this information to control the dual-rail encoders. The receiver measures polarization states and feeds back adjustment information to the transmitters, which then adjust their encoding parameters to compensate for fibre effects, creating a closed-loop control system.
2Productivity
If laser sources are injection locked to the same frequency, then interference efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses an intermediary approach by employing injection locking, where one laser source (the master) controls the frequency of another laser source (the slave). The master laser acts as an intermediary that transfers its stable frequency to the slave laser, enabling precise frequency matching without requiring both lasers to be manufactured with identical precision.
3Length of stationary object
If pre-compensation for fibre-induced polarization rotations is implemented, then communication distance is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-compensating for fibre-induced polarization rotations at the emitter side before light enters the fibre. The dual-rail encoders are controlled using compensation adjustment information to pre-adjust the polarization states, so that when light travels through the birefringent fibre, the polarization consistency is maintained at the receiver end.
4Reliability
If dual-rail encoding with phase and amplitude adjustments is used, then polarization consistency is improved, but ease of operation decreases
Solution Approach 1:
The patent implements feedback by obtaining compensation adjustment information concerning the fibres and using this information to control the dual-rail encoders. The receiver measures polarization states and feeds back adjustment information to the transmitters, which then adjust their encoding parameters to compensate for fibre effects, creating a closed-loop control system.
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
Enables efficient interference and reception of optical signals with consistent polarization, facilitating compact chip integration and simplified receiver design, enhancing communication reliability and distance in fibre-based systems.
Implementation Method 1
the light sources comprise laser sources operating at the same frequency, such that the laser sources are injection locked to the same frequency
Implementation Method 2
encoding, in each of the optical transmitters dual-rail encoded light in a respective dual-rail and converting, in each of the optical transmitters, the dual-rail encoded light into polarization encoded light
Implementation Method 3
converting the optical signals into dual rail form optical signals and causing the dual rail form optical signals to interfere with each other, measuring the dual rail form optical signals
Implementation Method 4
obtaining compensation adjustment information concerning two fibres and controlling the dual-rail encoders based at least in part on the compensation adjustment information
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
In accordance with an example embodiment of the present invention, there is provided an apparatus (160) comprising two inputs configured to receive two optical signals from two fibres (155, 157) from two respective optical transmitters, a beam splitter configured to convert the optical signals into dual rail form, the apparatus being configured to cause the optical signals to interfere with each other, a plurality of single photon detectors configured to measure the dual rail form optical signals, and at least one processing core configured to obtain compensation adjustment information concerning the two fibres and to inform the optical transmitters of the compensation adjustment information.