Electrostatic-Gated Optoelectronic Modulator for Low-BER Multilevel Links
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Solution Overview
Problem
Existing optoelectronic devices face challenges in achieving high data rates while maintaining a low Bit-Error-Rate (BER) and reducing electronic complexity, particularly with multilevel modulations like PAM-N, which degrade Signal-to-Noise Ratio (SNR) and increase power consumption.
Innovation Solution
An optoelectronic device with a semiconductor stack, electrostatic gate, and driver circuits that modulate light emission using a combination of voltage levels applied between electrodes and the electrostatic gate, enabling multilevel modulation without the need for complex DACs, by encoding electrical signals into separate parts for independent voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multilevel modulation (PAM-N) is used to increase data rate, then data rate increases, but Signal-to-Noise Ratio (SNR) decreases and Bit-Error-Rate (BER) increases
Solution Approach 1:
The patent divides the data stream into multiple parallel streams, each modulated onto a separate optical carrier wavelength. This segmentation allows each channel to use simpler modulation schemes (like OOK) while the aggregate system achieves multilevel data rates through parallel transmission, avoiding the SNR degradation of direct PAM-N modulation on a single channel.
Solution Approach 2:
The patent transitions from temporal modulation (PAM-N in time domain) to spectral modulation (multiple wavelengths in frequency domain). By moving to another dimension (wavelength/frequency), the system achieves high data rates without the SNR penalty associated with reducing amplitude separation in the time domain.
2Productivity
If multilevel modulation (PAM-N) is used to increase data rate, then data rate increases, but electronic complexity increases due to requirement of DAC and linear driver
Solution Approach 1:
The patent replaces complex electronic modulation systems (DAC + linear driver required for PAM-N) with a simpler optical approach using multiple wavelength channels. Each channel can use simple binary modulation controlled by standard digital logic, eliminating the need for high-speed DACs and linear drivers while achieving equivalent or higher data rates through spectral multiplexing.
Solution Approach 2:
The patent creates a multi-functional system where each wavelength channel serves as an independent transmission path that can carry its own data stream. This universal approach allows the system to achieve high data rates using simple, standardized digital modulation components that can be replicated across multiple channels, rather than requiring specialized complex modulation electronics.
3Productivity
If multilevel modulation (PAM-N) is used to increase data rate, then data rate increases, but power consumption increases
Solution Approach 1:
The patent replaces power-intensive electronic components (DAC and linear driver circuits required for PAM-N modulation) with simpler digital logic circuits that control multiple wavelength channels. This substitution dramatically reduces power consumption while maintaining or increasing data rate, as digital switching logic consumes far less power than high-speed analog conversion and linear amplification.
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 enhances data rate and reduces BER by optimizing SNR through independent voltage control, achieving efficient light emission with reduced electronic complexity and power consumption.
Implementation Method 1
A pLED is a microelectronic device that emits light when an electrical current flows through it. The optical power obtained at the output of the pLED depends on the value of the current injected through it.
Implementation Method 2
an electrostatic gate arranged against sidewalls of at least a part of the semiconductor stack
Data Source
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Figure 5~6
AI summary
An optoelectronic device (100) configured to convert an electrical digital information signal into a light digital information signal, comprising: - a semiconductor stack (120) including a first doped semiconductor portion (122) and a second doped semiconductor portion (124) forming together a PN junction; - a first electrode coupled to the first doped semiconductor portion, a second electrode coupled to the second doped semiconductor portion, and an electrostatic gate (140) arranged against sidewalls of the semiconductor stack; - a first driver circuit (160) comprising an input (162) configured to receive a first part of the electrical digital information signal and an output (164) coupled to the electrostatic gate and onto which, for each bit of the first part of the electrical digital information signal, a voltage is supplied, the value of which depends at least in part on that of said bit.