Coupling MicroLEDs to Waveguides via Parabolic Reflectors
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Solution Overview
Problem
The challenge in optical communication systems is efficiently coupling microLEDs to communication channels, particularly due to the mismatch between the wide angular spectrum of microLEDs and the limited numerical aperture of waveguides, leading to low coupling efficiency and increased power consumption in chip-to-chip connections.
Innovation Solution
The use of curved optical elements such as lenses and parabolic reflectors to trade off spatial and angular widths of microLED emission, allowing efficient coupling of light into waveguides or free-space propagation regions, and encapsulating microLEDs in high-index materials to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If microLEDs are directly coupled to waveguides, then the coupling efficiency is low due to angular spectrum mismatch, but adding optical elements increases device complexity
Solution Approach 1:
The patent introduces optical intermediary elements (lenses, parabolic reflectors, encapsulating materials) between the microLED and waveguide to mediate the angular spectrum mismatch. These intermediaries transform the wide angular emission from the microLED into a narrower angular distribution that matches the waveguide's numerical aperture, significantly improving coupling efficiency while keeping the added complexity manageable.
Solution Approach 2:
The patent modifies the angular and spatial parameters of the light emission by introducing optical elements that transform the angular spectrum. Lenses and parabolic reflectors change the angular distribution of emitted light, while high-index encapsulating materials modify the extraction efficiency and angular characteristics, thereby adapting the microLED output to match waveguide requirements.
2Adaptability or versatility
If chip-to-chip connections are used instead of on-chip connections, then more functionality can be achieved, but power consumption increases significantly
Solution Approach 1:
The patent replaces electrical signal transmission through physical chip-to-chip connections with optical signal transmission. By substituting electrical interconnects with optical interconnects using microLEDs and waveguides, the system achieves higher bandwidth and lower power consumption, as optical transmission eliminates resistive losses and enables more efficient data transfer between chips.
3Loss of energy
If microLEDs are encapsulated in high-index materials, then light extraction efficiency is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the refractive index parameter of the encapsulating material to be higher than both the microLED and waveguide materials. This parameter change increases the critical angle for total internal reflection, thereby enhancing light extraction efficiency from the microLED into the waveguide. The high-index material acts as an optical transformer that improves coupling without requiring extremely tight manufacturing tolerances.
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 enables high-density, low-power optical interconnects between chips and chiplets, improving coupling efficiency and reducing power consumption while allowing for broadcast functionality to multiple destinations.
Implementation Method 1
A microLED to be driven by the transceiver circuitry
Implementation Method 2
a photodetector to provide electrical signal carrying received information to the transceiver circuitry
Implementation Method 3
an array of multiple waveguide cores, including a plurality of waveguide cores configured to receive light emitted by the microLED
Data Source
AI summary
Light from one or more microLEDs may be coupled into multiple waveguide cores. Parabolic reflectors, truncated parabolic reflectors, and encapsulants may be used to increase fraction of emitted light coupled into the waveguide cores.