Coherent Optical Receiver Thyristor Phase Detection
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Solution Overview
Problem
Coherent optical receivers for PSK-modulated signals face challenges in accurately demodulating phase-shifted optical signals due to the need for precise phase alignment and synchronization between the received signal and the local oscillating signal, especially in higher-order PSK schemes, which can be complex and prone to errors.
Innovation Solution
The proposed coherent optical receiver employs thyristors and control circuitry to split and process combined optical signals with predefined phase offsets, using epitaxial layer structures and phototransistors to generate digital electrical or optical signals corresponding to phase offsets, enabling accurate demodulation of PSK signals, including binary and higher-order schemes, through optical hybrid couplers and XOR circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional photodetector networks are used for coherent BPSK demodulation, then the receiver can convert optical signals to electrical signals, but the system complexity increases and measurement precision deteriorates for higher-order PSK schemes
Solution Approach 1:
The patent replaces traditional photodetector-based electrical signal processing with a thyristor-based optical switching system. The thyristors directly modulate optical signals in response to phase differences between the received signal and local oscillator, eliminating the need for complex photodetector networks and electrical domain processing for higher-order PSK demodulation.
Solution Approach 2:
The patent divides the phase detection space into multiple discrete segments corresponding to different thyristor switching states. Each thyristor pair (Q1-Q2, Q3-Q4) represents a specific phase quadrant, and their selective activation directly encodes the detected phase information, simplifying the measurement of complex phase relationships.
2Reliability
If optical phase lock loops are used to synchronize local oscillating signal phase, then phase alignment is achieved, but the system becomes prone to errors and requires complex control mechanisms
Solution Approach 1:
The thyristor-based detector automatically adapts to the phase relationship between the received signal and local oscillator through its inherent switching characteristics. The system self-adjusts by selectively activating appropriate thyristor pairs based on the instantaneous phase difference, eliminating the need for external phase lock loop control mechanisms.
Solution Approach 2:
The patent implements implicit feedback through the thyristor switching states, which directly reflect the phase relationship. The output signals from different thyristor pairs provide immediate feedback about the phase alignment status, enabling reliable synchronization without complex control loops.
3Adaptability or versatility
If multiple photodetectors and signal processing circuits are deployed for higher-order PSK demodulation, then demodulation capability is enhanced, but error susceptibility increases and system reliability deteriorates
Solution Approach 1:
The patent replaces vulnerable electrical signal processing chains with robust optical switching using thyristors. This substitution reduces error susceptibility by eliminating analog-to-digital conversion stages and electrical signal routing, while maintaining compatibility with multiple PSK schemes through configurable thyristor activation patterns.
Solution Approach 2:
The thyristor-based detector serves multiple functions: it detects phase differences, demodulates various PSK schemes (BPSK, QPSK, 8-PSK), and provides error-resistant signal output through direct optical switching. The same hardware structure adapts to different modulation formats by changing the control logic for thyristor activation.
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 solution allows for efficient demodulation of PSK signals by accurately detecting phase offsets, improving the receiver's ability to recover original data with high precision across various PSK schemes, including binary and higher-order formats, thereby enhancing the reliability and accuracy of optical communication systems.
Implementation Method 1
controls switching operation of the at least one thyristor according to phase offset of optical PSK-modulated signal relative to the optical LO signal
Implementation Method 2
optical elements that combine the optical PSK-modulated signal and an optical local-oscillating (LO) signal
Implementation Method 3
epitaxial layer structures and phototransistors to generate digital electrical or optical signals corresponding to phase offsets
Data Source
AI summary
A coherent optical receiver that receives an optical PSK-modulated signal includes optical elements that combine the optical PSK-modulated signal and an optical local-oscillating (LO) signal and splits the combined optical signals into multiple parts that have a predefined phase offset relative to one another. The receiver further includes at least one thyristor and control circuitry operably coupled to terminals of the at least one thyristor. The control circuitry is configured to receive the multiple parts of the combined optical signals and controls switching operation of the at least one thyristor according to phase offset of optical PSK-modulated signal relative to the optical LO signal.