Optical Phase Shifter With Mismatched Waveguides
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Solution Overview
Problem
Conventional optical devices face challenges in emitting coherent optical radiation with controlled angular resolution and are prone to fabrication variations, leading to inefficient light emission and reduced fill factors, especially in compact designs for applications like LIDAR and communications.
Innovation Solution
The optical device incorporates multiple waveguides with phase mismatched propagation constants and grating antennas with adjusted grating periods to ensure coherent emission in a single direction, along with a separate perturbation layer for emitter elements, enhancing light emission efficiency and fill factor through a 'Tetris-style' modular approach.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical devices use standard waveguide configurations, then device structure is simple, but light emission coherence and angular resolution are poor
Solution Approach 1:
The patent applies local quality by assigning different propagation constants to different waveguides in the array. Each waveguide is locally optimized with specific propagation characteristics that differ from its neighbors, enabling precise control over the phase of emitted light from each element. This local differentiation allows the system to achieve high angular resolution through constructive and destructive interference patterns while maintaining a relatively simple overall waveguide array structure.
2Productivity
If grating antennas are used with standard grating periods, then fabrication is easier, but emission efficiency and fill factor are reduced
Solution Approach 1:
The patent implements parameter changes by systematically varying the grating periods of different grating antennas in the array. Each grating antenna is designed with a specific grating period that is tailored to its position and the propagation constant of its associated waveguide. This parameter optimization maximizes the coupling efficiency between the waveguide mode and the radiated mode, achieving high light emission efficiency and fill factor. The variations in grating periods are within manufacturable ranges, balancing performance with fabrication capabilities.
3Reliability
If waveguides have identical propagation constants, then device fabrication is simpler, but crosstalk between adjacent waveguides increases
Solution Approach 1:
The patent applies local quality by giving each waveguide a distinct propagation constant based on its position in the array. This local differentiation creates phase mismatches between adjacent waveguides, which suppresses evanescent coupling and reduces crosstalk. The propagation constants are locally optimized to ensure that light confined in one waveguide does not significantly couple to neighboring waveguides, improving signal integrity. The fabrication process remains relatively simple as it only requires controlling waveguide dimensions (such as width or height) to achieve the desired propagation constant variations.
4Stability of the object's composition
If all grating antennas have the same grating period, then device complexity is lower, but coherent emission in a single direction cannot be achieved
Solution Approach 1:
The patent implements asymmetry by designing grating antennas with different grating periods rather than using a uniform periodic structure. This asymmetric configuration of grating periods across the array is essential for achieving coherent emission in a single desired direction. The varying grating periods create specific phase relationships between elements that steer the beam in a controlled direction through phased array principles. While the overall structure remains regular and systematic, the deliberate asymmetry in grating periods enables directional control that would not be possible with identical periodic structures.
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 achieves unidirectional light emission with high efficiency (>90%) and increased fill factor, reducing crosstalk and fabrication-related issues, enabling compact and scalable optical devices for advanced applications.
Implementation Method 1
a first grating antenna having a first grating period; and a second grating antenna having a second grating period different from the first grating period. The first grating antenna is configured to emit first light from the first waveguide, and the second grating antenna is configured to emit second light from the second waveguide.
Data Source
AI summary
An optical phase shifter may include a waveguide core that has a top surface, and a semiconductor contact that is laterally displaced relative to the waveguide core and is electrically connected to the waveguide core. A top surface of the semiconductor contact is above the top surface of the waveguide core. The waveguide core may include a p-type core region and an n-type core region. A p-type semiconductor region may be in physical contact with the n-type core region of the waveguide core, and an n-type semiconductor region may be in physical contact with the p-type core region of the waveguide core. A phase shifter region and a light-emitting region may be disposed at different depth levels, and the light-emitting region may emit light from a phase shifter region that is in a position adjacent to the light-emitting region.