Optical Phased Array Beam Steering with Dual Focusing Elements
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Solution Overview
Problem
Optical phased arrays (OPAs) face limitations in steering and beam shaping, particularly in achieving compact and efficient mechanisms for steering in multiple axes while maintaining beam divergence and aperture size, which affects their application in LiDAR and free space optical communication systems.
Innovation Solution
The use of a photonic integrated circuit with a combination of focusing elements, including refractive and reflective surfaces, with different effective focal lengths, allows for beam expansion and steering in multiple axes, enabling compact OPA designs with larger effective apertures and reduced divergence, utilizing external beam expanders like parabolic mirrors for increased beam size and alignment sensitivity reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single focusing element is used to couple optical beams to/from the OPA, then the device structure is simple, but the beam size and divergence cannot be effectively controlled
Solution Approach 1:
The patent combines multiple focusing elements (first and second focusing elements) with different effective focal lengths into a single optical coupling system. This merging approach enables the system to perform multiple functions: beam expansion, divergence control, and coupling to/from the OPA, thereby resolving the contradiction between structural simplicity and beam control versatility.
2Object-affected harmful factors
If the OPA aperture size is increased to reduce beam divergence, then the beam divergence is reduced, but the device size and complexity increase
Solution Approach 1:
The patent introduces focusing elements as intermediary optical components between the OPA and the external environment. These intermediaries (lenses or mirrors) manipulate the optical beam to achieve divergence control and beam expansion without requiring an increase in the physical aperture size of the OPA itself, thus reducing device size while controlling beam divergence.
Solution Approach 2:
The patent changes the optical parameters of the beam by using focusing elements with different effective focal lengths. By adjusting the focal lengths and positions of these focusing elements, the system can control beam divergence and expand beam size without physically enlarging the OPA aperture, thereby resolving the contradiction between divergence reduction and device size increase.
3Area of moving object
If beam expansion is achieved to increase beam size, then the beam size increases, but the alignment sensitivity increases
Solution Approach 1:
The patent designs the focusing elements to serve multiple functions simultaneously: beam expansion, divergence control, and alignment tolerance compensation. The first focusing element couples the optical beam to/from the OPA while the second focusing element expands the beam and controls divergence. This multi-functional design allows the system to achieve beam expansion while maintaining acceptable alignment sensitivity through proper optical design.
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 compact, efficient OPAs with larger effective apertures and reduced beam divergence, improving alignment sensitivity and beam quality, allowing for larger beam sizes without increasing device size, suitable for LiDAR and free space optical communication systems.
Implementation Method 1
The first focusing element comprises a refractive element
Implementation Method 2
The first focusing element comprises a reflective surface
Implementation Method 3
The second focusing element comprises a refractive element
Implementation Method 4
The second focusing element comprises a reflective surface
Implementation Method 5
Each of the first and second focusing elements comprises a parabolic mirror configured to reflect an optical beam off-axis from an axis of the parabolic mirror
Data Source
AI summary
An apparatus comprises: a photonic integrated circuit comprising an optical phased array, a first focusing element at a fixed position relative to the optical phased array and configured to couple an optical beam to or from the optical phased array, and a second focusing element at a fixed position relative to the first focusing element and configured to couple the optical beam to or from the first focusing element. At least one of the first or second focusing element is externally coupled to the photonic integrated circuit, and the first and second focusing elements have different effective focal lengths.