Waveguide-Confining Layer for Subwavelength Laser Emission
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Solution Overview
Problem
Conventional photonic integrated circuit (PIC) technologies face challenges in integrating sub-wavelength laser emitters due to the limited optical confinement offered by conventional gain media with low refractive indices, leading to substantial surface and volume occupation, which restricts the integration with smaller-scale electronics.
Innovation Solution
A waveguide-confining layer is developed for PIC dies, comprising a silicon-based optical confinement structure vertically aligned with a horizontal slot between two blocking layers, where the gain medium has a lower refractive index than the blocking layers, allowing for sub-wavelength laser emission by refracting and confining light within the slot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional gain media with low refractive indices are used, then the laser structure can be simpler, but the optical confinement is limited and the laser occupies substantial surface area and volume
Solution Approach 1:
The patent segments the gain medium into a confined horizontal slot between two blocking layers, rather than using a conventional extended gain medium. This segmentation allows the laser to achieve sub-wavelength confinement (reducing surface area) while maintaining the necessary optical gain function through the slot-confined gain medium.
Solution Approach 2:
The patent implements a nested structure where the gain medium is confined within a horizontal slot that is itself embedded within the waveguide-confining layer, which contains the silicon-based optical confinement structure. This nested arrangement enables multiple confinement functions to be integrated in a compact vertical stack, reducing the overall laser footprint while maintaining optical performance.
2Length of moving object
If multiple device layers are used to achieve sub-wavelength laser beams, then the laser diameter can be reduced below wavelength, but the device complexity and volume increase
Solution Approach 1:
The patent transitions from conventional planar laser structures to a vertically stacked three-dimensional configuration. By confining the gain medium in a horizontal slot between blocking layers and positioning the silicon-based optical confinement structure vertically beneath it, the patent achieves sub-wavelength laser beam diameter through vertical dimension exploitation rather than horizontal expansion, thus reducing overall device complexity.
Solution Approach 2:
The patent employs a composite waveguide-confining layer structure combining blocking layers (metal or oxide), gain medium, oxide layer, and silicon-based optical confinement structure. This composite material approach enables simultaneous achievement of sub-wavelength confinement and integrated optical-electronic functionality within a unified multi-material system, reducing the need for separate device layers.
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
The solution enables the production of sub-wavelength laser beams with a diameter of approximately 300 nanometers, effectively reducing the size of the laser output and allowing for easier integration with other components on a PIC die, while maintaining efficient light transmission.
Implementation Method 1
the gain medium has a lower refractive index than each of the first blocking layer and the second blocking layer, wherein the gain medium is vertically aligned with the silicon-based optical confinement structure
Data Source
AI summary
Embodiments of the disclosure provide a waveguide-confining layer, a photonic integrated circuit (PIC) die with embodiments of a waveguide-confining layer, and methods to form the same. The waveguide-confining layer may include an oxide layer over a buried insulator layer, a silicon-based optical confinement structure embedded within or positioned on the oxide layer, and first and second blocking layers over the oxide layer and separated from each other by a horizontal slot. The first and second blocking layers include a metal or an oxide. A gain medium is positioned on the oxide layer and within the horizontal slot between the first and second blocking layers, and has a lower refractive index than each of the first and second blocking layers. The gain medium is vertically aligned with the silicon-based optical confinement structure, and a portion of the oxide layer separates the gain medium from the silicon-based optical confinement structure.