8DPSK Modulator Demodulator for Optical Transmission Capacity
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Solution Overview
Problem
Current multichannel optical communication systems face limitations in transmission capacity due to transitory responses and phase shifts caused by optical filtration, which degrade signal reconstruction and limit transmission distance and rate.
Innovation Solution
A modulator-demodulator system using an 8DPSK (Differential Phase Shift Keying) format with three cascade phase modulators and parallel Mach-Zehnder interferometers, implementing differential precoding and electronic signal processing to mitigate transitory responses and increase signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If optical filtration is used to transmit information over long distances, then transmission distance is improved, but transitory responses and phase shifts occur that degrade signal reconstruction
Solution Approach 1:
The patent segments the optical signal transmission into multiple phase-modulated components (eight distinct phase changes) that can be independently processed and reconstructed. By dividing the information into phase segments rather than transmitting as a single continuous signal, the system can better handle transitory responses caused by optical filtration.
Solution Approach 2:
The system applies preliminary phase encoding to the optical signal before transmission through the filtration system. By pre-modulating the signal with eight distinct phase changes, the transmitter prepares the signal to withstand the degradative effects of optical filtration, enabling accurate reconstruction at the receiver despite transitory responses.
2Productivity
If traditional modulation formats are used, then system simplicity is maintained, but transmission capacity is limited
Solution Approach 1:
The patent merges multiple phase modulation schemes into a unified eight-phase modulation format. By combining the advantages of differential phase shift keying with an extended phase alphabet, the system achieves three times the transmission capacity of traditional formats while integrating the functionality into a cohesive modulator-demodulator architecture.
Solution Approach 2:
The system transitions from traditional two-state or four-state phase modulation to an eight-state phase modulation dimension. By utilizing eight distinct phase changes instead of the conventional two or four phases, the system effectively adds a dimensional expansion to the modulation space, thereby tripling the information capacity per symbol.
3Reliability
If signal processing is enhanced to reduce chromatic scattering, then signal integrity is improved, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary differential encoding scheme that mediates between the transmitted signal and the degraded received signal. This differential phase encoding acts as a buffer that protects against chromatic scattering effects, allowing simple photodetector-based reception without requiring complex real-time signal processing while maintaining high signal integrity.
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 system achieves up to three times the communication capacity by effectively reducing chromatic scattering and maintaining signal integrity over longer distances, with improved spectral efficiency and reduced errors.
Implementation Method 1
parallel Mach-Zehnder interferometers
Implementation Method 2
three cascade phase modulators
Data Source
AI summary
The invention relates to a system comprising an optoelectronic modulator device and demodulator device for establishing communication between optical communication systems by means of differential modulation with eight phase changes. Said system can increase the information transmission capacity by up to three times that of a system with two phase changes. The modulation formats transmittable by the system are called: NRZ-D8PSK, RZ-D8PSK, D8PSK. The invention also relates to the design of the modulator which is formed by a differential modulation precoder and optical signal phase modulators, in which the signals leaving the precoder control the phase modulators in order to perform differential modulation with eight phase changes in relation to the optical signal originating from a semiconductor laser. The invention further relates to the design of a demodulator positioned at the terminal end of the communication system, formed by three receiver branches each containing different electronic devices used for the electronic processing of the signals received.