Grating Coupler Optic Subsystem for Bandwidth Extension
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Solution Overview
Problem
The bandwidth limitations of grating couplers in Silicon Photonics and VHIC technologies for WDM applications, particularly CWDM, are constrained by the angular dependence of wavelength emission, which restricts the ability of Single Mode Fibers to collect or inject multiple wavelengths due to fixed positioning and alignment, resulting in limited coupling efficiency.
Innovation Solution
An optic subsystem comprising a polynomial mirror and collimating lens modifies the angle distribution of light emitted by the grating coupler, and a focusing lens directs this modified light into the integrated device, effectively increasing the coupling bandwidth and reducing angular wavelength dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a grating coupler is used to couple light into an integrated device, then light coupling is enabled, but the bandwidth is limited due to angular wavelength dependence
Solution Approach 1:
A lens is introduced as an intermediary optical element between the grating coupler and the integrated device. The lens receives light at different angles from the grating coupler and focuses it onto the input facet of the integrated device, thereby decoupling the angular wavelength dependence from the coupling process and enabling broader bandwidth operation.
Solution Approach 2:
The system changes the angular parameter of light propagation by using a lens to transform the angular distribution of light from the grating coupler. By focusing light from different angles onto the same focal point at the integrated device input, the system maintains coupling efficiency across a broader wavelength range.
2Quantity of substance
If a single mode fiber is positioned at a fixed angle to collect light from a grating coupler, then coupling is achieved, but only one wavelength can be collected optimally
Solution Approach 1:
The lens acts as an intermediary that receives light from the grating coupler at various angles corresponding to different wavelengths and redirects it to a common focal point. This allows a single-mode fiber positioned at the focal point to collect multiple wavelengths simultaneously, overcoming the limitation of fixed positioning.
Solution Approach 2:
The lens transforms the angular dimension of light propagation into a spatial dimension at the focal plane. By doing so, it enables a single spatial position (the focal point where the fiber is positioned) to receive light across a spectrum of wavelengths that originally required different angular positions.
3Reliability
If conventional coupling is used with a grating coupler, then system simplicity is maintained, but coupling efficiency is limited at band edges
Solution Approach 1:
A lens is added as an intermediary optical component between the grating coupler and the integrated device. While this increases system complexity, it significantly improves coupling efficiency across the entire bandwidth, particularly at band edges, by properly focusing light from different angles onto the input facet of the integrated device.
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 the coupling efficiency by allowing multiple wavelengths to be focused into the integrated device, improving bandwidth and reducing losses at band edges, while maintaining compatibility with conventional systems and technologies like Silicon Photonics.
Implementation Method 1
emits by diffraction a emitted light 12R at different emission angles with a given angle distribution according to the different wavelengths λ1, λ2, λ3, as defined by the Grating Equation
Implementation Method 2
a collimating lens for modifying the beam angle of the beams in the reflected light
Implementation Method 3
a focusing lens to focus the collimated light with a modified angle distribution from the transmitter portion in a focused light beam into the integrated device
Data Source
AI summary
System for coupling light to integrated devices, comprising a grating coupler which couples light, such as light from a light source, into an optic fiber. The system includes an optic subsystem comprising a transmitter portion receiving the light emitted by the grating coupler and a receiver portion receiving light from the transmitter and focusing the light into the integrated device, the transmitter portion being configured to modify an angle distribution of the light emitted by the grating coupler and the receiving portion being configured to focus the light with modified angle distribution into the integrated device.