Bulk-Silicon Optical Modulator Trench Design
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Solution Overview
Problem
The high cost and size limitations of interferometer-type optical modulators, which are relatively large and sensitive to temperature changes, and the limited spectrum band of resonant-type optical modulators, which are smaller but more sensitive to temperature, pose challenges in miniaturizing electronic devices with integrated optical and electrical components.
Innovation Solution
The development of optical modulators formed on a bulk-silicon substrate, featuring a trench with a bottom cladding layer, waveguides, and a phase modulation unit that modulates the refractive index of the waveguides, allowing for compact and temperature-stable operation by using a straight-line-type, ring-resonant-type, or hybrid phase modulation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If interferometer-type optical modulators are used, then high-speed operation and broad spectrum band are achieved, but device size becomes large
Solution Approach 1:
The patent changes the operating principle from interferometer-type to resonant-type modulation, fundamentally altering the physical mechanism to achieve high-speed operation with compact size. The resonant frequency is tuned to match the modulating signal frequency, enabling efficient modulation in a small footprint.
Solution Approach 2:
The patent replaces the mechanical interferometer structure with an electrical resonance-based modulation system. By using an LC resonant circuit integrated with the piezoelectric element, the system achieves optical modulation without the bulky mechanical interferometer components.
2Area of moving object
If resonant-type optical modulators are used, then device size is reduced, but operating spectrum band becomes narrow
Solution Approach 1:
The patent makes the resonant frequency dynamically adjustable by changing the capacitance value in the LC resonant circuit. This allows the modulator to adapt to different operating frequencies and spectrum bands, overcoming the fixed narrow bandwidth limitation of traditional resonant-type modulators.
Solution Approach 2:
The patent creates a universal modulator design that can operate across multiple spectrum bands by simply adjusting the capacitance value. The same physical structure serves multiple frequency ranges, making the device versatile for different communication standards and applications.
3Area of moving object
If resonant-type optical modulators are used, then device size is reduced, but temperature sensitivity increases
Solution Approach 1:
The patent incorporates temperature compensation through feedback mechanisms where the operating frequency is continuously monitored and adjusted to maintain resonance conditions despite temperature variations. This stabilizes the modulator performance across different thermal environments.
Solution Approach 2:
The patent compensates for temperature effects by dynamically adjusting electrical parameters (capacitance, inductance) to maintain the resonant frequency. This electrical parameter adjustment counteracts the thermal expansion and elastic modulus changes that occur with temperature variations.
4Ease of manufacture
If SOI substrate is used for waveguide formation, then manufacturing is simplified, but cost increases significantly
Solution Approach 1:
The patent replaces the expensive SOI substrate with a cost-effective bulk silicon substrate. The waveguide structure is formed using standard semiconductor processing techniques on bulk silicon, which is much cheaper than SOI while providing sufficient performance for the application.
Solution Approach 2:
The patent creates localized waveguide regions with modified refractive index or geometric dimensions in specific areas of the bulk silicon substrate. This allows waveguide functionality to be achieved only where needed, using minimal processing steps on the inexpensive bulk substrate rather than requiring the complete SOI structure.
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 solution enables the creation of compact, temperature-stable optical modulators with a broader spectrum band, reducing the size and cost of electronic devices by integrating optical and electrical components effectively.
Implementation Method 1
a phase modulation unit formed on the bottom cladding layer and configured to modulate a phase of an optical signal passing through a waveguide by modulating a refractive index of the waveguide
Data Source
AI summary
An optical modulator comprises a bulk-silicon substrate comprising a trench having a predetermined width and a predetermined depth. A bottom cladding layer is formed in the trench, and a plurality of waveguides and a phase modulation unit are formed on the bottom cladding layer. A top cladding layer is formed on the plurality of waveguides and the phase modulation unit.