Bidirectional Photonic Integrated Circuit Reflection Suppression
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Solution Overview
Problem
Photonic integrated circuits face challenges in suppressing undesirable reflections, particularly in applications like low-coherence interferometry and optical coherence tomography, where existing methods such as tilting waveguide facets and anti-reflective coatings are insufficient in reducing reflection amplitudes, especially in large dynamic range detection and weak signal scenarios.
Innovation Solution
The design incorporates a photonic integrated circuit with a substrate and patterned waveguides that include a coupling region and optical modulating elements to adjust the phase of reflections, allowing constructive interference in one waveguide and destructive interference in the other, effectively canceling out unwanted reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tilting waveguide facets or applying anti-reflective coatings is used, then reflection amplitude is reduced by up to -40dB, but this level of suppression is insufficient for large dynamic range detection and weak signal applications
Solution Approach 1:
The patent converts the harmful reflected light into a beneficial component by using it for destructive interference. The reflected light from the waveguide facet is directed through a coupler to interfere destructively with the original reflected light, thereby converting the harmful reflection into a mechanism for reflection cancellation and achieving suppression beyond -40dB
Solution Approach 2:
The patent introduces a coupler as an intermediary element between the waveguide and the reflected light path. This coupler mediates the interaction between the reflected light and the original light path, enabling the destructive interference mechanism that achieves enhanced reflection suppression for weak signal detection applications
2Object-affected harmful factors
If conventional reflection suppression methods are used, then device structure remains simple, but reflection suppression is insufficient for applications like OCT systems
Solution Approach 1:
The patent merges the reflection suppression function with the existing waveguide structure by integrating couplers and interference mechanisms directly into the waveguide path. This combination approach achieves enhanced reflection suppression without requiring entirely separate suppression devices, thereby limiting the increase in device 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 approach significantly reduces unwanted reflections, achieving extinction ratios above -40dB, which is essential for maintaining signal quality in applications like OCT systems by minimizing interference from undesired light.
Implementation Method 1
The one or more modulating elements coupled to each of the first and second waveguides are designed to adjust the phase of the first and second reflections
Implementation Method 2
adjust the phase of the first and second reflections before the first and second reflections pass through the coupling region... constructive interference in one waveguide and destructive interference in the other, effectively canceling out unwanted reflections
Implementation Method 3
a coupling region, wherein the first and second waveguides each pass through the coupling region
Implementation Method 4
first and second reflections are generated at the first and second facets within the first and second waveguides, respectively
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A photonic integrated circuit (100) is presented that includes a substrate (102), and a first (204) and second waveguide (206) patterned on the substrate (102). The first waveguide (204) guides an input beam of radiation. The photonic integrated circuit also includes a coupling region (208), wherein the first and second waveguides (204, 206) each pass through the coupling region (208). One or more modulating elements (210) are coupled to each of the first and second waveguides (204, 206). The first waveguide (204) and the second waveguide (206) have a first facet (212a) and a second facet (212b), respectively, and first and second reflections are generated at the first and second facets (212a, 212b) within the first and second waveguides (204, 206), respectively. The one or more modulating elements (210) coupled to each of the first and second waveguides (204, 206) are designed to adjust the phase of the first and second reflections before the first and second reflections pass through the coupling region (208).