Dispersion-compensative optical assembly for fiber coupling
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Solution Overview
Problem
Grating couplers in optics communication face challenges with limited coupling bandwidth due to sensitivity to wavelength changes, leading to low efficiency as the fixed input direction from lenses can result in the light beam missing the waveguide, especially when dealing with fibers and silicon photonics chips.
Innovation Solution
An optical assembly comprising a first and second grating device, positioned between an optical fiber and a grating coupler, adjusts the propagation direction of light beams based on their wavelengths, ensuring optimal incidence angles for high coupling efficiency across different wavelengths, thereby increasing the coupling bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lens is used to focus the light beam from the fiber to the grating coupler, then the coupling efficiency is improved for a particular wavelength, but the coupling bandwidth is limited because the fixed input direction cannot accommodate wavelength changes
Solution Approach 1:
The patent introduces a tunable lens that can dynamically adjust its focal length and input direction based on the wavelength of the light beam. This dynamic adjustment capability allows the system to maintain optimal coupling conditions across a broad wavelength range, resolving the contradiction between achieving high coupling efficiency at a specific wavelength and maintaining adaptability across multiple wavelengths.
Solution Approach 2:
The patent changes the optical parameters (focal length, input direction) of the lens system based on the wavelength parameter of the light beam. By implementing wavelength-dependent parameter adjustments, the system can optimize coupling efficiency for each wavelength while maintaining broad bandwidth coverage, thus resolving the contradiction between specificity and versatility.
2Device complexity
If the grating coupler uses a fixed input direction, then the device complexity is reduced, but the coupling efficiency deteriorates when the wavelength changes causing the light beam to miss the waveguide
Solution Approach 1:
The patent implements a dynamic lens system that can adjust its focal length and orientation based on wavelength changes. This dynamic capability compensates for the fixed grating coupler structure, maintaining high coupling efficiency across different wavelengths without requiring a complex adjustable grating coupler, thus balancing device complexity with reliability.
Solution Approach 2:
The tunable lens acts as an intermediary between the fiber and the fixed grating coupler. It adapts the light beam parameters (direction, focus) to match the fixed grating coupler's requirements for different wavelengths, thereby maintaining high coupling efficiency without modifying the grating coupler structure itself.
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 optical assembly ensures high coupling efficiency for a range of wavelengths by adjusting input angles, maintaining efficient light coupling between fibers and silicon photonics chips, even when wavelengths vary, thus enhancing the grating coupler's performance.
Implementation Method 1
a first grating device configured to: receive a light beam that includes an optical signal with a particular wavelength from a fiber; and change a propagation direction of the optical signal according to the particular wavelength of the optical signal
Implementation Method 2
a lens may be placed between the fiber and the grating coupler to focus a light beam from the fiber to the grating coupler
Data Source
AI summary
An optical assembly includes a first grating device configured to: receive a light beam that includes an optical signal with a particular wavelength from a fiber; and change a propagation direction of the optical signal according to the particular wavelength of the optical signal. The optical assembly also includes a second grating device configured to: receive the optical signal outputted from the first grating device; change the propagation direction of the optical signal according to the particular wavelength of the optical signal; and direct the optical signal onto a grating coupler. The first grating device and the second grating device are configured to satisfy a plurality of configuration constraints.