Integrated Optical Modulation Element Extinction Ratio Variation
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Solution Overview
Problem
In wavelength division multiplexing communication systems, the increasing difference between the oscillation wavelengths of laser elements leads to extinction ratio variation among integrated optical modulation elements, which affects the performance of optical modules.
Innovation Solution
The solution involves designing semiconductor optical elements with integrated optical modulation elements where the oscillation wavelength of one element is longer than another, and the bandgap wavelength of the barrier layer in the quantum well core layer is correspondingly adjusted to reduce extinction ratio variation, achieved through specific manufacturing methods involving mask formation and etching processes on a semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the oscillation wavelength difference between laser elements is increased to support wider wavelength division multiplexing communication, then the communication capacity is improved, but the extinction ratio variation among optical modulators increases
Solution Approach 1:
The patent changes the bandgap wavelength parameter of the barrier layer in the quantum well core layer according to the oscillation wavelength of each laser element. By adjusting this parameter, the extinction ratio variation is reduced while maintaining the ability to support multiple wavelengths for high-capacity communication.
Solution Approach 2:
The patent applies different bandgap wavelengths to different barrier layers corresponding to different laser elements. This local differentiation allows each optical modulator to be optimized for its specific laser wavelength, reducing overall extinction ratio variation while maintaining high communication capacity.
2Reliability
If the bandgap wavelength of the barrier layer is adjusted to reduce extinction ratio variation, then the uniformity of optical modulators is improved, but the device structure complexity increases
Solution Approach 1:
The patent combines the laser element and optical modulator into a single integrated optical modulation element. This integration allows the bandgap wavelength adjustment to be implemented within a unified structure, reducing overall device complexity while achieving extinction ratio uniformity.
Solution Approach 2:
The patent uses a quantum well core layer with barrier layers having different bandgap wavelengths, creating a composite structure that can be grown monolithically on a single semiconductor substrate. This approach achieves parameter differentiation without requiring separate devices, thus managing complexity.
3Productivity
If multiple integrated optical modulation elements with different oscillation wavelengths are integrated on one semiconductor substrate, then the wavelength division multiplexing capability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent determines and sets the bandgap wavelength of each barrier layer in advance during the design stage, based on the oscillation wavelength of the corresponding laser element. This preliminary determination simplifies the manufacturing process by providing clear target parameters, thereby managing precision requirements.
Solution Approach 2:
The patent uses monolithic integration and epitaxial growth to create multiple optical modulation elements on a single semiconductor substrate, replacing mechanical assembly with a unified growth process. This substitution reduces the cumulative precision errors that would arise from assembling separate components.
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 effectively limits extinction ratio variation to within 0.1 dB, enhancing the uniformity and controllability of optical modules by optimizing the relationship between oscillation wavelengths and barrier layer bandgap wavelengths.
Implementation Method 1
the photoluminescence wavelength λPL of light absorption layers in a case where a multi-quantum-well core layer is used as a light absorption layer
Implementation Method 2
an electric-field-absorption-type optical modulator portion having a quantum well core layer that receives laser light from the laser element portion
Data Source
AI summary
A semiconductor optical element and an optical module in which extinction ratio variation among integrated optical modulation elements is reduced. An optical module has a wavelength multiplexer that multiplexes light respectively emerging from electric-field-absorption modulator (EAM) portions of integrated optical modulation elements, and that outputs the multiplexed light. The integrated optical modulation element has a signal input terminal, a laser element portion, and an EAM portion. Each of the integrated optical modulation elements has a difference between an oscillation wavelength and a barrier layer bandgap wavelength, represented as an LDBG wavelength difference. Variation of the LDBG wavelength differences is limited within a range of ±1 nm.