Direct-Modulation Laser Polarization Multiplexing for Higher-Speed CPFSK
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing CPFSK signal transmission systems using direct modulation lasers face challenges in increasing transmission speed without increasing circuit scale, as they primarily focus on frequency modulation while neglecting intensity modulation components, leading to SNR degradation and complex configurations.
Innovation Solution
A transmitting apparatus and method that independently modulates intensity and frequency components for orthogonal polarized waves, using a direct modulation laser, branching units, and polarized wave multiplexing to transmit these components separately, thereby maintaining signal quality and reducing DSP resource requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multilevel modulation is applied to increase transmission speed in the phase direction, then transmission speed is improved, but distance between signal points decreases causing SNR degradation
Solution Approach 1:
The patent transitions from single-dimensional phase modulation to two-dimensional modulation by utilizing both phase and intensity dimensions. CPFSK provides phase modulation while IM adds intensity modulation, creating a composite signal that transmits information in multiple dimensions simultaneously, thereby increasing transmission speed without compromising signal point separation in any single dimension
Solution Approach 2:
The patent creates a composite modulation signal combining CPFSK (phase modulation) and IM (intensity modulation). This composite approach integrates two different modulation techniques to achieve high-speed transmission while maintaining signal quality, as the phase and intensity components work together to provide redundancy and improve overall signal robustness
2Speed
If polarization multiplexing is implemented to increase transmission speed, then transmission speed is improved, but circuit configuration becomes complex
Solution Approach 1:
The patent merges CPFSK and IM into a single composite modulation scheme applied to direct modulation lasers. This integration eliminates the need for separate phase and intensity modulation circuits, reducing device complexity while achieving high-speed transmission through the combined effects of both modulation types
Solution Approach 2:
The direct modulation laser serves multiple functions simultaneously: it provides both phase modulation (through CPFSK) and intensity modulation (through IM) using a single device. This multi-functionality eliminates the need for separate modulation circuits for each polarization, thereby reducing overall circuit complexity while enabling polarization multiplexing for high-speed transmission
3Speed
If intensity modulation component is generated during CPFSK signal generation, then transmission speed is improved, but signal quality (SNR) deteriorates
Solution Approach 1:
The patent converts the previously harmful intensity modulation component into a beneficial element by deliberately incorporating IM as a intentional modulation scheme. The intensity variations that were causing SNR degradation are now controlled and structured to carry additional information, transforming a harmful artifact into a useful feature that enhances transmission speed
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 approach allows for high-speed polarization multiplexing without increasing circuit complexity, preventing SNR degradation and reducing the need for additional DSP resources due to frequency offset estimation.
Implementation Method 1
a direct modulation laser; a branching unit that branches continuous phase frequency shift keying signal light having been generated by the direct modulation laser
Implementation Method 2
a polarized wave multiplexing unit that multiplexes the first polarized wave signal light and the second polarized wave signal light
Data Source
AI summary
A transmitting apparatus includes a direct modulation laser, a branching unit, a first signal generation unit, a second signal generation unit, and a polarized wave multiplexing unit. The branching unit branches continuous phase frequency shift keying signal light having been generated by the direct modulation laser by applying a first modulation signal into first branch light and second branch light. The first signal generation unit generates first polarized wave signal light obtained by removing an intensity modulation component having been generated by the direct modulation laser by applying the first modulation signal from the first branch light. The second signal generation unit generates second polarized wave signal light obtained by removing the intensity modulation component from the second branch light and adding an intensity modulation component to the second branch light by applying a second modulation signal, the second polarized wave being orthogonal to the first polarized wave. The polarized wave multiplexing unit multiplexes the signal light for the first polarized wave and the signal light for the second polarized wave.