Suspended Silicon Nitride Waveguide for Crosstalk Reduction
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Solution Overview
Problem
Current silicon nitride phased array beam-deflecting chips face crosstalk issues due to the refractive index difference between the silicon nitride core layer and silicon oxide cladding layer, limiting the scanning range when waveguide array elements are closely spaced, which results in side lobes near the main peak and restricted beam scanning.
Innovation Solution
A silicon nitride phased array chip with a suspended waveguide structure, featuring a silicon nitride waveguide area with a silicon substrate, silicon dioxide buffer and cladding layers, and a suspended waveguide area with a second curved waveguide and array grating antenna, where the waveguides are spaced closely to prevent crosstalk and enable large-angle beam scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between waveguide array elements is reduced to increase integration density, then the scanning angle is improved, but crosstalk between adjacent waveguides increases due to limited refractive index difference
Solution Approach 1:
The patent introduces an air gap as an intermediary medium between adjacent silicon nitride waveguides. This air gap acts as a refractive index barrier that prevents optical coupling and crosstalk between waveguides, enabling the waveguides to be placed closer together without signal interference. The air gap serves as a mediator that allows high integration density while maintaining waveguide isolation.
Solution Approach 2:
The patent changes the physical parameters of the waveguide structure by reducing the distance between adjacent waveguides and introducing air gaps. This parameter change enables closer spacing of waveguide elements, increasing integration density and enabling larger scanning angles while the air gap maintains optical isolation to prevent crosstalk.
2Reliability
If the refractive index difference between core and cladding is increased to reduce crosstalk, then waveguide isolation is improved, but the transmission spectrum becomes more limited
Solution Approach 1:
The air gap serves as an intermediary that provides waveguide isolation without requiring a large refractive index difference between core and cladding materials. The air gap creates an effective barrier to optical coupling through its distinct refractive index (1.0), allowing waveguide isolation to be achieved while maintaining a broad transmission spectrum through the silicon nitride waveguide core.
3Adaptability or versatility
If waveguides are placed closer together to reduce side lobes and improve scanning range, then the beam scanning performance is improved, but crosstalk between adjacent waveguides deteriorates
Solution Approach 1:
The air gap introduced between adjacent waveguides acts as a mediator that enables closer spacing while preventing crosstalk. This allows the waveguide array to achieve improved beam scanning performance with reduced side lobes, as the air gap maintains optical isolation even when waveguides are positioned closer together to optimize scanning range.
Data Source
AI summary
A silicon nitride phased array chip based on a suspended waveguide structure, which includes a silicon nitride waveguide area and a suspended waveguide area. The silicon nitride waveguide area includes a silicon substrate, a silicon dioxide buffer layer, a silicon dioxide cladding layer and a silicon nitride waveguide-based core layer. The silicon nitride waveguide-based core layer includes an optical splitter unit, a first curved waveguide, a thermo-optic phase shifter and a spot-size converter. The suspended waveguide area includes a second curved waveguide and an array grating antenna.