Optical Transmitter Laser Drive Control for Multi-Carrier Systems
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Solution Overview
Problem
Current optical transmission systems using direct modulation schemes for semiconductor lasers lack optimization of drive conditions based on transmission characteristics, which affects spectral efficiency and transmission capacity.
Innovation Solution
An optical transmission system that includes an optical transmitter and receiver, where the receiver monitors subcarrier reception characteristics and feeds back results to the transmitter to control the drive conditions of the semiconductor laser, optimizing its operation for improved transmission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct modulation scheme is used for semiconductor laser, then cost and device size are reduced, but transmission speed and spectral efficiency deteriorate
Solution Approach 1:
The patent implements dynamic control of the semiconductor laser drive conditions by monitoring subcarrier reception characteristics and adjusting drive current amplitude and bias current in real-time. This dynamic adaptation enables the direct modulation scheme to achieve optimized transmission performance across varying channel conditions, resolving the contradiction between using simple direct modulation and maintaining high transmission speed.
Solution Approach 2:
The patent changes the drive conditions parameters (amplitude and bias current) of the semiconductor laser based on monitored transmission characteristics. By adjusting these parameters dynamically, the system optimizes spectral efficiency and transmission speed while maintaining the cost-effective direct modulation architecture.
2Productivity
If bit loading is applied to allocate bits to subcarriers based on transmission characteristic, then spectral efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the optical receiver monitors subcarrier reception characteristics (SNR, BER) and feeds this information back to the optical transmitter. The transmitter then adjusts bit allocation and drive conditions based on this feedback, enabling adaptive spectral efficiency optimization without requiring complex centralized control.
Solution Approach 2:
The system performs self-optimization by automatically adjusting bit loading and drive conditions based on monitored transmission characteristics. This self-service approach eliminates the need for external complex control systems while maintaining high spectral efficiency through adaptive resource allocation.
3Reliability
If drive conditions of semiconductor laser are optimized for each transmission characteristic, then transmission performance is improved, but control complexity and monitoring requirements increase
Solution Approach 1:
The patent uses feedback from subcarrier reception characteristic monitoring to automatically adjust drive conditions. This feedback loop enables the system to maintain optimal transmission performance across varying conditions without requiring complex manual control or prediction mechanisms.
Solution Approach 2:
The patent introduces a monitoring and control mechanism that acts as an intermediary between the transmission channel and the laser drive conditions. This intermediary automatically adjusts parameters based on channel conditions, simplifying the overall control architecture while maintaining optimized performance.
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 enhances spectral efficiency and transmission capacity by optimizing the drive conditions of the semiconductor laser, thereby improving signal quality and reducing costs through dynamic control of the laser's drive conditions.
Implementation Method 1
an electric/optic (E/O) converter using a direct modulation scheme for a semiconductor laser is applicable to an optical transmitter
Implementation Method 2
an optic/electric (O/E) converter using a light reception element such as a PD (photo detector or photo diode) is applicable to an optical receiver
Data Source
AI summary
An optical transmitter transmits to an optical receiver a multi-carrier modulated signal light by driving a light source with a modulated signal modulated with a multi-carrier modulation scheme. The optical receiver monitors reception characteristic of any of subcarrier signals included in the modulated signal and transmits a monitor result to the optical transmitter. The optical transmitter controls drive conditions of the light source based on the monitor result received from the optical receiver.