Optoelectronic Device Evanescent Wave Coupling for Sensitivity Bandwidth Trade-off
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Solution Overview
Problem
Existing optoelectronic devices for high bit rate digital optical signal reception face challenges in achieving optimal signal-to-noise ratio and bandwidth due to the conflicting requirements of active area thickness for optical amplifiers and photodiodes, leading to inefficiencies in signal transmission and processing.
Innovation Solution
The use of a diluted multimode waveguide structure, comprising a stack of alternating thin layers, is introduced to facilitate evanescent wave coupling between the optical amplification and photoreception sections, allowing for separate optimization of active area thickness and improving signal transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the active area thickness is increased to improve photodiode sensitivity, then the photodiode can detect weaker signals, but the bandwidth is reduced due to increased capacitance
Solution Approach 1:
The device is divided into two separate functional sections: an optical amplification section with a thin active area (3-5 μm) for high-speed operation, and a photodetection section with a thick active area (10-20 μm) for high sensitivity. This segmentation allows each section to be optimized independently for its specific function without compromise.
Solution Approach 2:
Different regions of the device have different active area thicknesses tailored to their specific functions. The optical amplification region has a thin active area to minimize capacitance and maximize bandwidth, while the photodetection region has a thick active area to maximize light absorption and sensitivity. This local differentiation resolves the contradiction between sensitivity and bandwidth.
2Loss of energy
If optical mode adapters or tapers are used to adapt different active area sizes, then coupling efficiency improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The optical amplification section and photodetection section are merged into a single monolithic integrated device fabricated on the same semiconductor substrate. This integration eliminates the need for separate optical mode adapters or tapers to couple between different structures, reducing device complexity while maintaining efficient optical coupling through the evanescent field interaction in the common substrate.
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 linearity, gain, noise reduction, and bandwidth while maintaining sensitivity and independence from light polarization, achieving a conversion quantum efficiency of 80% and minimizing coupling loss.
Implementation Method 1
a diluted multimode waveguide common to both sections, the first active area and the second area being disposed so as to ensure a coupling by evanescent waves with said diluted multimode waveguide
Data Source
AI summary
The field of the invention is that of optoelectronic devices for receiving high bit rate digital optical signals for telecommunications applications, comprising an optical amplifier and a photoreceiver diode.Generally, the two optical amplification and optical-electrical conversion functions are integrated in a common component, resulting in lower production costs, smaller footprint and improved reliability.To optimize the conversion device as a whole, it is demonstrated that there must be an active area of small thickness in the amplifier part and greater thickness in the conversion part.The invention proposes to implement this function by means of a structure comprising a diluted multimode waveguide common to the two amplification and reception sections, the first active area and the second area being disposed so as to ensure a coupling by evanescent waves with said diluted multimode waveguide.