Oblique Waveguide Resonance Suppression in Optical Modules
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Solution Overview
Problem
The challenge in optical communication systems is the degradation of output signals due to undesirable resonance between grating couplers and reflection points during wafer-level testing of photonic integrated circuit chips, which affects the performance and yield of silicon photonics-based optical transceivers.
Innovation Solution
The implementation of oblique waveguides for coupling test light to and from the optical circuits on the chip, either by providing grating couplers outside the chip area or optically isolating them from the actual transmission/reception paths, reduces resonance and signal degradation by minimizing reflections at the chip edges during service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If grating couplers are provided in each chip area for wafer-level testing, then testing efficiency is improved, but undesirable resonance occurs between grating couplers and reflection points causing signal degradation
Solution Approach 1:
The patent extracts the grating coupler from the chip area and places it on the substrate outside the chip area. This separation allows wafer-level testing to be performed while preventing the grating coupler from causing resonance with reflection points on the chip, thus resolving the contradiction between testing efficiency and signal quality.
Solution Approach 2:
The patent introduces an oblique waveguide as an intermediary component between the grating coupler (located outside the chip area) and the optical circuit on the chip. This oblique waveguide serves as a mediator that enables light transmission while its oblique orientation prevents resonance with reflection points, thereby maintaining both testing efficiency and signal quality.
2Reliability
If grating couplers are placed on the substrate outside chip area, then resonance is suppressed, but light input/output to chip areas becomes more complex
Solution Approach 1:
The oblique waveguide serves multiple functions: it transmits light from the grating coupler to the optical circuit, and its oblique orientation inherently prevents resonance with reflection points. This multi-functionality reduces the need for additional resonance-suppression structures, thereby managing complexity while achieving reliable resonance suppression.
3Reliability
If oblique waveguides are used for light input/output, then resonance is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the orientation parameter of the waveguide from horizontal (parallel to chip edge) to oblique (at an angle to chip edge). This parameter change fundamentally alters the resonance condition, reducing resonance effects. While this introduces alignment considerations, the oblique angle creates a geometric relationship that naturally reduces resonance sensitivity compared to horizontal alignment.
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 effectively suppresses noise and signal degradation, enhancing the efficiency of wafer-level testing and maintaining signal quality during actual service by preventing undesirable resonance between grating couplers and reflection points.
Implementation Method 1
a first oblique waveguide extending obliquely with respect to an edge of the substrate at or near an incident port for introducing a light emitted from a light source to the optical device
Implementation Method 2
grating couplers are provided in each of the chip areas over the wafer
Data Source
AI summary
An optical device with an optical transmitter circuit and an optical receiver circuit integrated on a substrate has at least one of a first oblique waveguide extending obliquely with respect to an edge of the substrate at or near an incident port for introducing a light emitted from a light source to the optical device, a second oblique waveguide extending obliquely with respect to the edge of the substrate at or near a signal receiving port optically connected to the optical receiver circuit, and a third oblique waveguide extending obliquely with respect to the edge of the substrate at or near a signal transmission port optically connected to the optical transmitter circuit.