Scavenging Photodetection Device for Silicon Photonics Alignment
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Solution Overview
Problem
Existing photodetection devices in silicon photonics face challenges due to wavelength dependence and polarization sensitivity of directional couplers, leading to optical loss and misalignment issues during packaging and assembly of lasers and fibers with integrated photonics chips.
Innovation Solution
A scavenging photodetection device with an optical coupling portion using a primary taper coupler and light absorbers to direct collected light to a photonic integrated circuit, and a scavenging photodetection portion with a secondary taper coupler and photodetector to monitor alignment without power splitters or taps, reducing wavelength dependence and optical loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a directional coupler is used to tap light for optical power monitoring, then alignment position can be determined, but wavelength dependence and polarization sensitivity cause optical loss and fabrication variations
Solution Approach 1:
The patent extracts the light sampling function from the main optical path by using a small portion of the input waveguide mode to couple light to the photodetector, rather than using a directional coupler that requires tapping a significant percentage of light. This extraction approach allows monitoring without substantial optical loss in the primary path.
Solution Approach 2:
The patent applies local quality by creating a localized coupling region where only a small portion of the waveguide mode interacts with the monitoring path, while the rest of the optical path maintains its original characteristics. This is achieved through a localized perturbation in the waveguide structure that couples light to the photodetector without affecting the main beam.
2Measurement precision
If a directional coupler is used for light tapping, then optical power monitoring is enabled, but fabrication variations and wavelength dependence reduce reliability
Solution Approach 1:
The patent changes the coupling mechanism from a directional coupler with fixed coupling coefficients to a localized coupling structure where the coupling strength is determined by geometric parameters that are less sensitive to fabrication variations. This approach reduces wavelength dependence and improves reliability across different operating conditions.
3Measurement precision
If a small percentage of light is tapped from the input waveguide, then optical power monitoring is achieved, but optical loss increases
Solution Approach 1:
The patent extracts a minimal amount of light from the main optical path just sufficient for monitoring purposes, using a localized coupling mechanism that removes only the necessary portion of light energy. This extraction is achieved through a small perturbation in the waveguide that couples light to the photodetector without significant loss to the primary beam.
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
Enables precise monitoring of input power during alignment and assembly, reducing optical crosstalk and fabrication sensitivity, while utilizing otherwise wasted light, thus improving alignment accuracy and reducing optical loss.
Implementation Method 1
an optical coupler configured to receive light from a light source, and at least one primary input waveguide optically coupled to the optical coupler and configured to direct collected light to a photonic integrated circuit
Implementation Method 2
a plurality of light absorbers arranged to absorb the light from the light source that is not collected by the optical coupler
Implementation Method 3
a primary photodetector configured to collect uncollected light from the optical coupling portion to determine an alignment position of the photonic integrated circuit
Data Source
AI summary
A scavenging photodetection device (10) is provided. The scavenging photodetection device (10) includes an optical coupling portion (12) and a scavenging photodetection portion (14). The optical coupling portion (12) includes an optical coupler (16) configured to receive light from a light source, a plurality of light absorbers (18) arranged to absorb the light from the light source that is not collected by the optical coupler (16), and at least one primary input waveguide (20) optically coupled to the optical coupler (16) and configured to direct collected light to a photonic integrated circuit. The scavenging photodetection portion (14) includes a primary photodetector (22) configured to collect uncollected light from the optical coupling portion (12) to determine an alignment position of the photonic integrated circuit.