Laser Light Source With Series Optical Modulators
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Solution Overview
Problem
Conventional laser light source apparatuses face a trade-off between widening the frequency band and maintaining a sufficient extinction ratio due to the use of a single optical modulator, where shortening the modulator to widen the band compromises the extinction ratio.
Innovation Solution
The apparatus incorporates a semiconductor optical modulation device with multiple optical modulators separated from each other, connected in series, which reduces electrostatic capacitance and allows for a wider frequency band while maintaining an equivalent extinction ratio through differential driving and electro-absorption optical modulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the optical modulator is shortened to widen the band, then the frequency band is improved, but the extinction ratio deteriorates
Solution Approach 1:
The single optical modulator is divided into multiple optical modulators (first, second, and third optical modulators) connected in series. Each modulator has a shortened length to reduce electrostatic capacitance and widen the frequency band, while the series connection maintains the overall extinction ratio performance. This segmentation allows each component to be optimized for bandwidth without compromising the system-level extinction ratio requirement.
2Speed
If multiple optical modulators are used instead of a single modulator, then the frequency band is widened, but the device complexity increases
Solution Approach 1:
Multiple optical modulators are combined in a series configuration within a unified semiconductor optical modulation device structure. The modulators share common electrodes and are integrated on a single chip, which reduces the overall complexity compared to using separate discrete modulators. The series connection allows the system to achieve widened bandwidth while maintaining a compact, integrated design that minimizes external connection complexity.
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 configuration enhances frequency band gain, achieving a 3 dB passband of 63 GHz compared to 33 GHz in conventional systems, while ensuring an equivalent extinction ratio and reducing assembly complexity and cost.
Implementation Method 1
the plurality of electro-absorption optical modulators
Data Source
AI summary
A lead pin (2a,2b) penetrates a metal stem (1). A support block (3) is mounted on the metal stem (1). A dielectric substrate (4) is mounted on a side surface of the support block (3). A signal line (5a,5b) is formed on the dielectric substrate (4). One end of the signal line (5a,5b) is connected to the lead pin (2a,2b). A semiconductor optical modulation device (6) is mounted on the dielectric substrate (4). A conductive wire (8a,8b) connects the other end of the signal line (5a,5b) and the semiconductor optical modulation device (6). The semiconductor optical modulation device (6) includes a plurality of optical modulators (6b,6c) separated from each other.