Low-Voltage Silicon Micro-Ring Modulator via PIN Diode Injection
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Solution Overview
Problem
Existing electro-optic devices require high operating voltages, which hinder their integration with nanoelectronic devices and increase energy consumption and circuit footprint, necessitating the development of low-voltage operation technologies compatible with silicon semiconductor materials.
Innovation Solution
A monocrystalline silicon micro-ring electro-optic charge carrier injection based modulator device is fabricated with a 2.5 micron radius, operating at a peak-to-peak drive voltage of 150 mV, achieving efficient modulation by biasing near the optimum charge carrier injection efficiency point, utilizing a PIN diode structure with doped regions to minimize contact and series resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high operating voltage is used in electro-optic devices, then reliable signal modulation is achieved, but integration with nanoelectronic devices is hindered and energy consumption increases
Solution Approach 1:
The patent changes the electrical parameters of the electro-optic modulator by introducing a resonant cavity structure that enhances the electric field intensity within the active region. This allows the device to achieve reliable signal modulation at lower operating voltages by concentrating the electrical energy in a specific spatial region, thereby reducing overall energy consumption while maintaining modulation reliability
Solution Approach 2:
The patent transitions from a planar waveguide structure to a three-dimensional resonant cavity structure. This dimensional change creates a confined optical mode volume that interacts more efficiently with the electro-optic material, enabling lower voltage operation through enhanced field confinement and increased interaction length without proportionally increasing device footprint
2Reliability
If high operating voltage is used in electro-optic devices, then signal modulation is maintained, but device footprint and circuit complexity increase
Solution Approach 1:
The patent modifies the optical parameters by designing a resonant cavity with specific dimensions that support high-Q modes. This allows the device to achieve effective modulation with a compact footprint by utilizing resonant enhancement rather than requiring long interaction lengths, thus reducing the device area while maintaining signal modulation performance
Solution Approach 2:
The patent implements a nested structure where the optical waveguide is embedded within the resonant cavity, which itself is integrated with the electro-optic active region. This nested architecture allows multiple functional elements to occupy overlapping spatial volumes, reducing the overall device footprint while maintaining all necessary modulation functions
3Ease of manufacture
If conventional electro-optic structures are used, then fabrication is straightforward, but low voltage operation below 500 mV is not achieved
Solution Approach 1:
The patent changes the structural parameters of the electro-optic modulator by introducing a resonant cavity with specifically engineered dimensions and geometry. This structural parameter change creates strong field confinement that enhances the electro-optic interaction efficiency, enabling operation at voltages below 500 mV while maintaining compatibility with standard semiconductor fabrication processes
Solution Approach 2:
The patent employs a composite structure combining different semiconductor materials with complementary properties - such as high-index contrast materials for confinement and low-loss materials for waveguiding. This composite approach enables both low-voltage operation through enhanced field confinement and ease of manufacture through compatibility with established heteroepitaxial growth techniques
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 approach enables high-speed, low-voltage operation of electro-optic modulators, facilitating seamless integration with CMOS nanoelectronics and reducing energy consumption and device size, while maintaining efficient signal modulation.
Implementation Method 1
electro-optic charge carrier injection based modulator device
Implementation Method 2
charge carrier injection based modulator device (i.e., predicated upon a PIN diode)
Data Source
AI summary
An electro-optic modulator structure, a method for fabricating the electro-optic modulator structure, a method for operating an electro-optic modulator device that derives from the electro-optic modulator structure and a related communications apparatus that includes the electro-optic modulator structure all are directed towards effecting a comparatively low voltage operation of the electro-optic modulator device predicated upon consideration of optimal charge carrier injection efficiency characteristics of a PIN diode charge carrier injection based micro-ring electro-optic modulator structure as a function of applied bias voltage. To realize the foregoing result, at least in part, the PIN diode charge carrier injection based electro-optic modulator structure includes at least one of a p-doped region and an n-doped region that has a relatively high volume dopant concentration at a surface thereof.