Suspended Silicon Electro-Optic Modulator Design
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Solution Overview
Problem
Silicone-based electro-optic modulators face challenges with poor uniformity and high electrical resistance, limiting their bandwidth and efficiency in high-speed optical communication systems.
Innovation Solution
An electro-optic modulator with a doped structure featuring P-type and N-type doped regions connected by link arms, forming PN junction depletion layers perpendicular to the light propagation direction, which are periodically arranged to enhance modulation efficiency and reduce resistance through full etching and specific doping concentrations, allowing the modulator to operate in the TM mode and reduce optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If partial etching is used to form the slab area of the ridge waveguide, then the modulator can be manufactured, but the thickness control becomes difficult causing poor uniformity
Solution Approach 1:
The patent removes the slab area entirely from the ridge waveguide structure through full etching, eliminating the manufacturing difficulty associated with controlling slab thickness. This extraction of the problematic component resolves the contradiction by making thickness control trivial while maintaining manufacturability through the alternative suspended ridge waveguide design.
2Device complexity
If the slab area thickness is reduced, then the modulator structure is formed, but the electrical resistance becomes high limiting the bandwidth
Solution Approach 1:
The patent transitions from a planar ridge waveguide to a vertically suspended structure, changing the dimensional arrangement of the waveguide. This dimensional change allows the optical mode to be confined in the vertical direction while providing adequate horizontal space for low-resistance electrical contacts, thereby resolving the contradiction between structure formation and bandwidth performance.
3Ease of operation
If the ridge waveguide structure is used, then the modulator can operate, but optical losses occur due to interactions with the surfaces
Solution Approach 1:
The patent extracts the ridge structure from contact with the substrate surface by creating a suspended configuration. This removal of the ridge-waveguide-surface interaction eliminates the source of optical losses while maintaining the modulator's operational functionality through the suspended waveguide design that preserves optical confinement.
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 solution achieves high bandwidth, low losses, and improved modulation efficiency by reducing electrical resistance and enhancing uniformity, while operating in the TM mode to minimize optical interactions with the modulator's surfaces, thus improving overall performance.
Implementation Method 1
the most feasible and commonly used technical solution at present is a Carrier Depletion Modulator based on a plasma dispersion effect
Data Source
AI summary
An electro-optic modulator includes a doped structure disposed on a top silicon layer of a substrate. The doped structure includes an optical waveguide, and a first P-type doped region and a first N-type doped region disposed respectively on two sides of the optical waveguide. The first P-type doped region is connected to the optical waveguide by means of a plurality of P-type doped link arms, and the first N-type doped region is connected to the optical waveguide by means of a plurality of N-type doped link arms. End portions of the plurality of P-type doped link arms and end portions of the plurality of N-type doped link arms are alternately arranged along a direction of light propagation to form PN junction depletion layers. The PN junction depletion layers are periodically arranged along the direction of light propagation to form the optical waveguide.