Optical Phased Array Beam Steering With Slab-Relayed Side-Lobe Suppression
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Solution Overview
Problem
Conventional optical phased arrays (OPAs) struggle to achieve wide steering angles and suppress side lobes for light beams in the visible spectrum due to grating spacing limitations and crosstalk, leading to significant side lobe formation.
Innovation Solution
A beam-steering device with a waveguide array, phase shifter, and grating array, incorporating a slab propagation region that forms the light beam before coupling out, allowing the main lobe to reach the grating array while side lobes are suppressed by guiding them away from the slab region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If grating spacing is reduced to less than half the wavelength to suppress side lobes, then side lobe suppression is improved, but device complexity and manufacturing difficulty increase significantly for visible spectrum light
Solution Approach 1:
The device segments the grating structure into multiple independent grating periods with different spacing values. The first grating period has spacing d1 ≥ λ/2 while the second grating period has spacing d2 < λ/2, allowing different regions to serve different functions: the first period suppresses grating lobes while the second period suppresses side lobes, resolving the contradiction between side lobe suppression and manufacturing feasibility
Solution Approach 2:
Different regions of the grating array are assigned different local properties: the first grating period uses larger spacing suitable for visible light manufacturing, while the second grating period uses smaller spacing optimized for side lobe suppression. This local differentiation allows each region to optimize for its specific function without compromising the entire device
2Ease of manufacture
If grating spacing is increased for easier manufacture with visible light, then ease of manufacture is improved, but side lobe suppression deteriorates due to crosstalk between gratings
Solution Approach 1:
The grating array is divided into two distinct periods: the first period uses manufacturable spacing (d1 ≥ λ/2) to avoid crosstalk, while the second period uses smaller spacing (d2 < λ/2) to suppress side lobes. The segmented structure ensures that each period's spacing optimization does not compromise the other period's function
Solution Approach 2:
The first grating period acts as an intermediary structure that prevents crosstalk between adjacent gratings by using sufficient spacing, thereby enabling the second grating period to use smaller spacing for side lobe suppression without suffering from manufacturing-related crosstalk issues
3Device complexity
If a single grating period is used to simplify device structure, then device complexity is reduced, but the ability to simultaneously suppress both grating lobes and side lobes deteriorates
Solution Approach 1:
The grating array is segmented into two functional periods: the first period targets grating lobe suppression with spacing d1 ≥ λ/2, while the second period targets side lobe suppression with spacing d2 < λ/2. This segmentation enables simultaneous suppression of both types of unwanted emissions that a single period cannot address
Solution Approach 2:
The dual-period grating structure provides multi-functionality: it simultaneously performs grating lobe suppression (function of first period), side lobe suppression (function of second period), and maintains a compact integrated design. Each period contributes a different function, making the overall structure universally effective against multiple types of unwanted emissions
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 device achieves suppressed side lobes and precise beam steering in the visible spectrum, enabling applications like augmented reality displays and neural probes without the need for additional components, and is compatible with integrated photonic platforms.
Implementation Method 1
multiple waveguides (14-1, 14-2, ..., 14-i) adapted for simultaneously guiding light from the waveguide array input (12) to the waveguide array output (16) and for forming a light beam by superimposing the light guided by the waveguides
Implementation Method 2
phase shifter device (18) arranged for applying controlled phase shifts to the light guided in each of the waveguides (14-1, 14-2, ..., 14-i)
Implementation Method 3
grating array (22) including at least one patterned grating configured to radiate the light beam out of the beam-steering device (100) to a surrounding
Implementation Method 4
a slab propagation region (20) arranged between the waveguide array output (16) and the grating array (22) such that the light beam is formed with a main lobe and side lobes and with a beam angle (φ) in the slab propagation region (20), wherein the main lobe of the light beam is angularly relayed to the grating array (22) and the side lobes of the light beam are guided away from the slab propagation region (20)
Data Source
AI summary
A beam-steering device (100) for spatial steering of a light beam comprises a waveguide array (10) being arranged on a substrate (50) and comprising a waveguide array input (12), multiple waveguides (14-1, 14-2, . . . , 14-i) and a waveguide array output (16), wherein the multiple waveguides (14-1, 14-2, . . . , 14-i) are adapted for simultaneously guiding light from the waveguide array input (12) to the waveguide array output (16) and for forming a light beam downstream of the waveguide array output (16) by superimposing the light guided by the waveguides (14-1, 14-2, . . . , 14-i), a phase shifter device (18) being arranged for applying controlled phase shifts to the light guided in each of the waveguides (14-1, 14-2, . . . , 14-i), and a grating array (22) including at least one patterned grating in optical communication with the waveguide array output (16), the grating array (22) being configured to radiate the light beam out of the beam-steering device (100) to a surrounding, wherein the waveguide array output (16) is arranged such that the light beam is formed downstream of the waveguide array output (16) with a main lobe and side lobes and with a beam angle Φ in a plane of the substrate (50), that is determined by the controlled phase shifts applied to the light by the phase shifter device (18) and a wavelength of the light, a slab propagation region (20) is arranged between the waveguide array output (16) and the grating array (22) such that the main lobe of the light beam is angularly relayed to the grating array (22) and the side lobes of the light beam leave lateral sides of the slab propagation region (20) before reaching the grating array (22), and the grating array (22) is arranged to radiate the light beam out of the beam-steering device (100) with a first angular direction with respect to the substrate (50), that is determined by the beam angle Φ. Furthermore, a method of beam-steering a light beam is described.