Thermo-Optical Phase Modulator with Self-Aligned Thermal Trenches
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Solution Overview
Problem
Current thermo-optic phase modulators in optical phased arrays (OPAs) face challenges in compactness and modulation frequency due to the need for precise alignment and thermal diffusion, limiting their effectiveness in compact, high-density OPA designs, particularly at submicron wavelengths.
Innovation Solution
A thermo-optical phase modulator design with a waveguide, encapsulation layer, and heating element, where the heating element forms the flanks of trenches, allowing self-aligned etching and direct contact with air in the trenches, enhancing thermal confinement and optical confinement, reducing the modulator's width and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation trenches are formed on either side of the modulator to confine heat, then thermal isolation between adjacent modulators is improved, but the device width increases and compactness deteriorates
Solution Approach 1:
The patent combines the trench formation with the heating element fabrication process. The heating element is deposited and patterned to directly form the trench walls, merging two previously separate structures (trenches and heating element) into a single integrated component. This eliminates the need for separate insulation trenches while maintaining thermal confinement, thereby reducing device width without compromising thermal isolation.
Solution Approach 2:
The heating element serves multiple functions: it provides thermal confinement by forming the trench walls, acts as the heating source, and defines the optical mode confinement region. This multi-functionality eliminates the need for separate insulation structures, achieving both thermal isolation and compactness through a single element.
2Area of stationary object
If the grating pitch is reduced to increase modulator density, then OPA compactness is improved, but manufacturing alignment precision requirements worsen
Solution Approach 1:
The heating element and trench structure are merged into a single deposited layer, eliminating the need for separate alignment between trench formation and heating element placement. This integration removes a critical alignment step, allowing smaller grating pitches without increasing manufacturing complexity or reducing yield.
Solution Approach 2:
The heating element is deposited and patterned before final trench etching, establishing the precise lateral boundaries early in the fabrication process. This preliminary definition of boundaries simplifies subsequent processing steps and reduces cumulative alignment errors that would otherwise accumulate with multiple lithography steps.
3Area of stationary object
If the modulator width is reduced to increase density, then OPA compactness is improved, but heat diffusion to adjacent modulators worsens
Solution Approach 1:
The heating element forms the lateral boundaries of the heat confinement region, merging the thermal management function with the optical confinement structure. This integration ensures that heat is confined precisely where needed without requiring additional lateral spacing, enabling compact modulator design while preventing heat diffusion to adjacent devices.
4Ease of manufacture
If standard trench etching is used with separate masks, then manufacturing process is simplified, but device width increases and compactness deteriorates
Solution Approach 1:
The heating element deposition and trench formation are merged into a single lithography and etching sequence. The heating element material serves as the trench definition layer, eliminating the need for separate mask alignment and reducing the number of fabrication steps while simultaneously reducing device width.
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 design achieves increased compactness and modulation frequency, enabling closer placement of modulators and efficient heat management, suitable for compact OPAs operating at submicron wavelengths with reduced energy consumption.
Implementation Method 1
a so-called heating element configured to heat the waveguide
Implementation Method 2
Insulation trenches 21, 22 are generally formed on either side of the modulator 1, so as to confine the heat produced by the heating element to the waveguide
Implementation Method 3
a waveguide configured to guide a light beam of wavelength λ
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
The invention relates to a thermo-optical phase modulator (1) comprising, in a stack, a waveguide (11), an encapsulation layer (12) and a heating element (13) configured to heat the waveguide (11), said modulator (1) being bordered by first and second trenches (21, 22). Advantageously, the waveguide (11), the encapsulation layer (12) and the heating element (13) each have first and second flanks (111, 112, 121, 122, 131, 132) forming at least in part the flanks (210, 220) of the trenches (21, 22). The flanks of the waveguide, the encapsulation layer and the heating element thus lead directly into the trenches that border the modulator. The invention also relates to a method for producing such a compact modulator.